hydrogen), while the thermal diffusivities of gases, calculated according to Clausius’ and Maxwell’s kinetic theory of gases, are 0.089 for carbonic acid, 0.16 for common air of other gases of nearly the same density, and 1.12 for hydrogen (all, both material and thermal, being reckoned in square centimeters per second).]
Rich as it is in practical results, the kinetic theory of gases, as hitherto developed, stops absolutely short at the atom or molecule, and gives not even a suggestion toward explaining the properties in virtue of which the atoms or molecules mutually influence one another. For some guidance toward a deeper and more comprehensive theory of matter, we may look back with advantage to the end of last century and beginning of this century, and find Rumford’s conclusion regarding the heat generated in boring a brass gun: “It appears to me to be extremely difficult, if not quite impossible, to form any distinct idea of anything capable of being excited and communicated in the manner the heat was excited and communicated in these experiments, except it be MOTION;” and Davy’s still more suggestive statements: “The phenomena of repulsion are not dependent on a peculiar elastic fluid for their existence.” … “Heat may be defined as a peculiar motion, probably a vibration, of the corpuscles of bodies, tending to separate them.” … “To distinguish this motion from others, and to signify the causes of our sensations of heat, etc., the name _repulsive_ motion has been adopted.” Here we have a most important idea. It would be somewhat a bold figure of speech to say the earth and moon are kept apart by a repulsive motion; and yet, after all, what is centrifugal force but a repulsive motion, and may it not be that there is no such thing as repulsion, and that it is solely by inertia that what seems to be repulsion is produced? Two bodies fly together, and, accelerated by mutual attraction, if they do not precisely hit one another, they cannot but separate in virtue of the inertia of their masses. So, after dashing past one another in sharply concave curves round their common center of gravity, they fly asunder again. A careless onlooker might imagine they had repelled one another, and might not notice the difference between what he actually sees and what he would see if the two bodies had been projected with great velocity toward one another, and either colliding and rebounding, or repelling one another into sharply convex continuous curves, fly asunder again.
Joule, Clausius, and Maxwell, and no doubt Daniel Bernoulli himself, and I believe every one who has hitherto written or done anything very explicit in the kinetic theory of gases, has taken the mutual action of molecules in collision as repulsive. May it not after all be attractive? This idea has never left my mind since I first read Davy’s “Repulsive Motion,” about thirty-five years ago, and I never made anything of it, at all events have not done so until to-day (June 16, 1884)–if this can be said to be making anything of it–when, in endeavoring to prepare the present address, I notice that Joule’s and my own old experiments[1] on the thermal effect of gases expanding from a high-pressure vessel through a porous plug, proves the less dense gas to have greater intrinsic _potential_ energy than the denser gas, if we assume the ordinary hypothesis regarding the temperature of a gas, according to which two gases are of equal temperatures [2] when the kinetic energies of their constituent molecules are of equal average amounts per molecule.
[Footnote 1: Republished in Sir W. Thomson’s “Mathematical and Physical Papers,” vol. i., article xlix., p. 381. ]
[Footnote 2: That this is a mere hypothesis has been scarcely remarked by the founders themselves, nor by almost any writer on the kinetic theory of gases. No one has yet examined the question, What is the condition as regards average distribution of kinetic energy, which is ultimately fulfilled by two portions of gaseous matter, separated by a thin elastic septum which absolutely prevents interdiffusion of matter, while it allows interchange of kinetic energy by collisions against itself? Indeed, I do not know but, that the present is the very first statement which has ever been published of this condition of the problem of equal temperatures between two gaseous masses.]
Think of the thing thus. Imagine a great multitude of particles inclosed by a boundary which may be pushed inward in any part all round at pleasure. Now station an engineer corps of Maxwell’s army of sorting demons all round the inclosure, with orders to push in the boundary diligently everywhere, when none of the besieged troops are near, and to do nothing when any of them are seen approaching, and until after they have turned again inward. The result will be that, with exactly the same sum of kinetic and potential energies of the same inclosed multitude of particles, the throng has been caused to be denser. Now Joule’s and my own old experiments on the efflux of air prove that if the crowd be common air, or oxygen, or nitrogen, or carbonic acid, the temperature is a little higher in the denser than in the rarer condition when the energies are the same. By the hypothesis, equality of temperature between two different gases or two portions of the same gas at different densities means equality of kinetic energies in the same number of molecules of the two. From our observations proving the temperature to be higher, it therefore follows that the potential energy is smaller in the condensed crowd. This–always, however, under protest as to the temperature hypothesis–proves some degree of attraction among the molecules, but it does not prove ultimate attraction between two molecules in collision, or at distances much less than the average mutual distance of nearest neighbors in the multitude. The collisional force might be repulsive, as generally supposed hitherto, and yet attraction might predominate in the whole reckoning of difference between the intrinsic potential energies of the more dense and less dense multitudes.
It is however remarkable that the explanation of the propagation of sound through gases, and even of the positive fluid pressure of a gas against the sides of the containing vessel, according to the kinetic theory of gases, is quite independent of the question whether the ultimate collisional force is attractive or repulsive. Of course it must be understood that, if it is attractive, the particles must, be so small that they hardly ever meet–they would have to be infinitely small to _never_ meet–that, in fact, they meet so seldom, in comparison with the number of times their courses–are turned through large angles by attraction, that the influence of these surely attractive collisions is preponderant over that of the comparatively very rare impacts from actual contact. Thus, after all, the train of speculation suggested by Davy’s “Repulsive Motion” does not allow us to escape from the idea of true repulsion, does not do more than let us say it is of no consequence, nor even say this with truth, because, if there are impacts at all, the nature of the force during the impact and the effects of the mutual impacts, however rare, cannot be evaded in any attempt to realize a conception of the kinetic theory of gases. And in fact, unless we are satisfied to imagine the atoms of a gas as mathematical points endowed with inertia, and as, according to Boscovich, endowed with forces of mutual, positive, and negative attraction, varying according to some definite function of the distance, we cannot avoid the question of impacts, and of vibrations and rotations of the molecules resulting from impacts, and we must look distinctly on each molecule as being either a little elastic solid or a configuration of motion in a continuous all-pervading liquid. I do not myself see how we can ever permanently rest anywhere short of this last view; but it would be a very pleasant temporary resting-place on the way to it if we could, as it were, make a mechanical model of a gas out of little pieces of round, perfectly elastic solid matter, flying about through the space occupied by the gas, and colliding with one another and against the sides of the containing vessel.
This is, in fact, all we have of the kinetic theory of gases up to the present time, and this has done for us, in the hands of Clausius and Maxwell, the great things which constitute our first step toward a molecular theory of matter. Of course from it we should have to go on to find an explanation of the elasticity and all the other properties of the molecules themselves, a subject vastly more complex and difficult than the gaseous properties, for the explanation of which we assume the elastic molecule; but without any explanation of the properties of the molecule itself, with merely the assumption that the molecule has the requisite properties, we might rest happy for a while in the contemplation of the kinetic theory of gases, and its explanation of the gaseous properties, which is not only stupendously important as a step toward a more thoroughgoing theory of matter, but is undoubtedly the expression of a perfectly intelligible and definite set of facts in Nature.
But alas for our mechanical model consisting of the cloud of little elastic solids flying about among one another. Though each particle have absolutely perfect elasticity, the end must be pretty much the same as if it were but imperfectly elastic. The average effect of repeated and repeated mutual collisions must be to gradually convert all the translational energy into energy of shriller and shriller vibrations of the molecule. It seems certain that each collision must have something more of energy in vibrations of very finely divided nodal parts than there was of energy in such vibrations before the impact. The more minute this nodal subdivision, the less must be the tendency to give up part of the vibrational energy into the shape of translational energy in the course of a collision; and I think it is rigorously demonstrable that the whole translational energy must ultimately become transformed into vibrational energy of higher and higher nodal subdivisions if each molecule is a continuous elastic solid. Let us, then, leave the kinetic theory of gases for a time with this difficulty unsolved, in the hope that we or others after us may return to it, armed with more knowledge of the properties of matter, and with sharper mathematical weapons to cut through the barrier which at present hides from us any view of the molecule itself, and of the effects other than mere change of translational motion which it experiences in collision.
To explain the elasticity of a gas was the primary object of the kinetic theory of gases. This object is only attainable by the assumption of an elasticity more complex in character, and more difficult of explanation, than the elasticity of gases–the elasticity of a solid. Thus, even if the fatal fault in the theory, to which I have alluded, did not exist, and if we could be perfectly satisfied with the kinetic theory of gases founded on the collisions of elastic solid molecules, there would still be beyond it a grander theory which need not be considered a chimerical object of scientific ambition–to explain the elasticity of solids. But we may be stopped when we commence to look in the direction of such a theory with the cynical question, What do you mean by explaining a property of matter? As to being stopped by any such question, all I can say is that if engineering were to be all and to end all physical science, we should perforce be content with merely finding properties of matter by observation, and using them for practical purposes. But I am sure very few, if any, engineers are practically satisfied with so narrow a view of their noble profession. They must and do patiently observe, and discover by observation, properties of matter and results of material combinations. But deeper questions are always present, and always fraught with interest to the true engineer, and he will be the last to give weight to any other objection to any attempt to see below the surface of things than the practical question, Is it likely to prove wholly futile? But now, instead of imagining the question, What do you mean by explaining a property of matter? to be put cynically, and letting ourselves be irritated by it, suppose we give to the questioner credit for being sympathetic, and condescend to try and answer his question. We find it not very easy to do so. All the properties of matter are so connected that we can scarcely imagine one _thoroughly explained_ without our seeing its relation to all the others, without in fact having the explanation of all; and till we have this we cannot tell what we mean by “explaining a property” or “explaining the properties” of matter. But though this consummation may never be reached by man, the progress of science may be, I believe will be, step by step toward it, on many different roads converging toward it from all sides. The kinetic theory of gases is, as I have said, a true step on one of the roads. On the very distinct road of chemical science, St. Claire Deville arrived at his grand theory of dissociation without the slightest aid from the kinetic theory of gases. The fact that he worked it out solely from chemical observation and experiment, and expounded it to the world without any hypothesis whatever, and seemingly even without consciousness of the beautiful explanation it has in the kinetic theory of gases, secured for it immediately an independent solidity and importance as a chemical theory when he first promulgated it, to which it might even by this time scarcely have attained if it had first been suggested as a probability indicated by the kinetic theory of gases, and been only afterward confirmed by observation. Now, however, guided by the views which Clausius and Williamson have given us of the continuous interchange of partners between the compound molecules constituting chemical compounds in the gaseous state, we see in Deville’s theory of dissociation a point of contact of the most transcendent interest between the chemical and physical lines of scientific progress.
To return to elasticity: if we could make out of matter devoid of elasticity a combined system of relatively moving parts which, in virtue of motion, has the essential characteristics of an elastic body, this would surely be, if not positively a step in the kinetic theory of matter, at least a fingerpost pointing a way which we may hope will lead to a kinetic theory of matter. Now this, as I have already shown,[1] we can do in several ways. In the case of the last of the communications referred to, of which only the title has hitherto been published, I showed that, from the mathematical investigation of a gyrostatically dominated combination contained in the passage of Thomson and Tait’s “Natural Philosophy” referred to, it follows that any ideal system of material particles, acting on one another mutually through massless connecting springs, may be perfectly imitated in a model consisting of rigid links jointed together, and having rapidly rotating fly wheels pivoted on some or on all of the links. The imitation is not confined to cases of equilibrium. It holds also for vibration produced by disturbing the system infinitesimally from a position of stable equilibrium and leaving it to itself. Thus we may make a gyrostatic system such that it is in equilibrium under the influence of certain positive forces applied to different points of this system; all the forces being precisely the same as, and the points of application similarly situated to, those of the stable system with springs. Then, provided proper masses (that is to say, proper amounts and distributions of inertia) be attributed to the links, we may remove the external forces from each system, and the consequent vibration of the points of application of the forces will be identical. Or we may act upon the systems of material points and springs with any given forces for any given time, and leave it to itself, and do the same thing for the gyrostatic system; the consequent motion will be the same in the two cases. If in the one case the springs are made more and more stiff, and in the other case the angular velocities of the fly wheels are made greater and greater, the periods of the vibrational constituents of the motion will become shorter and shorter, and the amplitudes smaller and smaller, and the motions will approach more and more nearly those of two perfectly rigid groups of material points moving through space and rotating according to the well known mode of rotation of a rigid body having unequal moments of inertia about its three principal axes. In one case the ideal nearly rigid connection between the particles is produced by massless, exceedingly stiff springs; in the other case it is produced by the exceedingly rapid rotation of the fly wheels in a system which, when the fly wheels are deprived of their rotation, is perfectly limp.
[Footnote 1: Paper on “Vortex Atoms,” _Proc_. R.S.E. February. 1867: abstract of a lecture before the Royal Institution of Great Britain, March 4, 1881, on “Elasticity Viewed as possibly a Mode of Motion”; Thomson and Tait’s “Natural Philosophy,” second edition, part 1, Sec.Sec. 345 viii. to 345 xxxvii.; “On Oscillation and Waves in an Adynamic Gyrostatic System” (title only), _Proc_. R.S.E. March, 1883.]
The drawings (Figs. 1 and 2) before you illustrate two such material systems.[1] The directions of rotation of the fly-wheels in the gyrostatic system (Fig. 2) are indicated by directional ellipses, which show in perspective the direction of rotation of the fly-wheel of each gyrostat. The gyrostatic system (Fig. 2) might have been constituted of two gyrostatic members, but four are shown for symmetry. The inclosing circle represents in each case in section an inclosing spherical shell to prevent the interior from being seen. In the inside of one there are fly-wheels, in the inside of the other a massless spring. The projecting hooked rods seem as if they are connected by a spring in each case. If we hang any one of the systems up by the hook on one of its projecting rods, and hang a weight to the hook of the other projecting rod, the weight, when first put on, will oscillate up and down, and will go on doing so for ever if the system be absolutely unfrictional. If we check the vibration by hand, the weight will hang down at rest, the pin drawn out to a certain degree; and the distance drawn out will be simply proportional to the weight hung on, as in an ordinary spring balance.
[Footnote 1: In Fig. 1 the two hooked rods seen projecting from the sphere are connected by an elastic coach-spring. In Fig. 2 the hooked rods are connected one to each of two opposite corners of a four-sided jointed frame, each member of which carries a gyrostat so that the axis of rotation of the fly-wheel is in the axis of the member of the frame which bears it. Each of the hooked rods in Fig. 2 is connected to the framework through a swivel joint, so that the whole gyrostatic framework may be rotated about the axis of the hooked rods in order to annul the moment of momentum of the framework about this axis due to rotation of the fly-wheels in the gyrostat.]
[Illustration: FIG. 1]
[Illustration: FIG. 2]
Here, then, out of matter possessing rigidity, but absolutely devoid of elasticity, we have made a perfect model of a spring in the form of a spring balance. Connect millions of millions of particles by pairs of rods such as these of this spring balance, and we have a group of particles constituting an elastic solid; exactly fulfilling the mathematical ideal worked out by Navier, Poisson, and Cauchy, and many other mathematicians, who, following their example, have endeavored to found a theory of the elasticity of solids on mutual attraction and repulsion between a group of material particles. All that can possibly be done by this theory, with its assumption of forces acting according to any assumed law of relation to distance, is done by the gyrostatic system. But the gyrostatic system does, besides, what the system of naturally acting material particles cannot do–it constitutes an elastic solid which can have the Faraday magneto-optic rotation of the plane of polarization of light; supposing the application of our solid to be a model of the luminiferous ether for illustrating the undulatory theory of light. The gyrostatic model spring balance is arranged to have zero moment of momentum as a whole, and therefore to contribute nothing to the Faraday rotation; with this arrangement the model illustrates the luminiferous ether in a field unaffected by magnetic force. But now let there be a different rotational velocity imparted to the jointed square round the axis of the two projecting hooked rods, such as to give a resultant moment of momentum round any given line through the center of inertia of the system; and let pairs of the hooked rods in the model thus altered, which is no longer a model of a mere spring balance, be applied as connections between millions of pairs of particles as before, with the lines of resultant moment of momentum all similarly directed. We now have a model elastic solid which will have the property that the direction of vibration in waves of rectilinear vibrations propagated through it shall turn round the line of propagation of the waves, just as Faraday’s observation proves to be done by the line of vibration of light in a dense medium between the poles of a powerful magnet. The case of wave front perpendicular to the lines of resultant moment of momentum (that is to say, the direction of propagation being parallel to these lines) corresponds, in our mechanical model, to the case of light traveling in the direction of the lines of force in a magnetic field.
In these illustrations and models we have different portions of ideal rigid matter acting upon one another, by normal pressure at mathematical points of contact–of course no forces of friction are supposed. It is exceedingly interesting to see how thus, with no other postulates than inertia, rigidity, and mutual impenetrability, we can thoroughly model not only an elastic solid, and any combination of elastic solids, but so complex and recondite a phenomenon as the passage of polarized light through a magnetic field. But now, with the view of ultimately discarding the postulate of rigidity from all our materials, let us suppose some to be absolutely destitute of rigidity, and to possess merely inertia and incompressibility, and mutual impenetrability with reference to the still remaining rigid matter. With these postulates we can produce a perfect model of mutual action at a distance between solid particles, fulfilling the condition, so keenly desired by Newton and Faraday, of being explained by continuous action through an intervening medium. The law of the mutual force in our model, however, is not the simple Newtonian law, but the much more complex law of the mutual action between electro magnets–with this difference, that in the hydro-kinetic model in every case the force is opposite in direction to the corresponding force in the electro-magnetic analogue. Imagine a solid bored through with a hole, and placed in our ideal perfect liquid. For a moment let the hole be stopped by a diaphragm, and let an impulsure pressure be applied for an instant uniformly over the whole membrane, and then instantly let the membrane be dissolved into liquid. This action originates a motion of the liquid relatively to the solid, of a kind to which I have given the name of “irrotational circulation,” which remains absolutely constant however the solid be moved through the liquid. Thus, at any time the actual motion of the liquid at any point in the neighborhood of the solid will be the resultant of the motion it would have in virtue of the circulation alone, were the solid at rest, and the motion it would have in virtue of the motion of the solid itself, had there been no circulation established through the aperture. It is interesting and important to remark in passing that the whole kinetic energy of the liquid is the sum of the kinetic energies which it would have in the two cases separately. Now, imagine the whole liquid to be inclosed in an infinitely large, rigid, containing vessel, and in the liquid, at an infinite distance from any part of the containing vessel, let two perforated solids, with irrotational circulation through each, be placed at rest near one another. The resultant fluid motion due to the two circulations, will give rise to fluid pressure on the two bodies, which, if unbalanced, will cause them to move. The force systems–force-and-torques, or pairs of forces–required to prevent them from moving will be mutual and opposite, and will be the same as, but opposite in direction to, the mutual force systems required to hold at rest two electromagnets fulfilling the following specification: The two electro magnets are to be of the same shape and size as the two bodies, and to be placed in the same relative positions, and to consist of infinitely thin layers of electric currents in the surfaces of solids possessing extreme diamagnetic quality–in other words, infinitely small permeability. The distribution of electric current on each body may be any whatever which fulfills the condition that the total current across any closed line drawn on the surface once through the aperture is equal to 1/4 [pi] of the circulation[1] through the aperture in the hydro-kinetic analogue.
[Footnote 1: The integral of tangential component velocity all round any closed curve, passing once through the aperture, is defined as the “cyclic-constant” or the “circulation” (“Vortex Motion,” Sec. 60 (a), _Trans_. R.S.E., April 29, 1867). It has the same value for all closed curves passing just once through the aperture, and it remains constant through all time, whether the solid body be in motion or at rest.]
It might be imagined that the action at a distance thus provided for by fluid motion could serve as a foundation for a theory of the equilibrium, and the vibrations, of elastic solids, and the transmission of waves like those of light through an extended quasi-elastic solid medium. But unfortunately for this idea the equilibrium is essentially unstable, both in the case of magnets and, notwithstanding the fact that the forces are oppositely directed, in the hydro-kinetic analogue also, when the several movable bodies (two or any greater number) are so placed relatively as to be in equilibrium. If, however, we connect the perforated bodies with circulation through them in the hydro-kinetic system, by jointed rigid connecting links, we may arrange for configurations of stable equilibrium. Thus, without fly-wheels, but with fluid circulations through apertures, we may make a model spring balance or a model luminiferous ether, either without or with the rotational quality corresponding to that of the true luminiferous ether in the magnetic fluid–in short, do all by the perforated solids with circulations through them that we saw we could do by means of linked gyrostats. But something that we cannot do by linked gyrostats we can do by the perforated bodies with fluid circulation: we can make a model gas. The mutual action at a distance, repulsive or attractive according to the mutual aspect of the two bodies when passing within collisional distance[1] of one another, suffices to produce the change of direction of motion in collision, which essentially constitutes the foundation of the kinetic theory of gases, and which, as we have seen before, may as well be due to attraction as to repulsion, so far as we know from any investigation hitherto made in this theory.
[Footnote 1: According to this view, there is no precise distance, or definite condition respecting the distance, between two molecules, at which apparently they come to be in collision, or when receding from one another they cease to be in collision. It is convenient, however, in the kinetic theory of gases, to adopt arbitrarily a precise definition of collision, according to which two bodies or particles mutually acting at a distance may be said to be in collision when their mutual action exceeds some definite arbitrarily assigned limit, as, for example, when the radius of curvature of the path of either body is less than a stated fraction (one one-hundredth, for instance) of the distance between them.]
There remains, however, as we have seen before, the difficulty of providing for the case of actual impacts between the solids, which must be done by giving them massless spring buffers or, which amounts to the same thing, attributing to them repulsive forces sufficiently powerful at very short distances to absolutely prevent impacts between solid and solid; unless we adopt the equally repugnant idea of infinitely small perforated solids, with infinitely great fluid circulations through them. Were it not for this fundamental difficulty, the hydro-kinetic model gas would be exceedingly interesting; and, though we could scarcely adopt it as conceivably a true representation of what gases really are, it might still have some importance as a model configuration of solid and liquid matter, by which without elasticity the elasticity of true gas might be represented.
But lastly, since the hydro-kinetic model gas with perforated solids and fluid circulations through them fails because of the impacts between the solids, let us annul the solids and leave the liquid performing irrotational circulation round vacancy,[1] in the place of the solid cores which we have hitherto supposed; or let us annul the rigidity of the solid cores of the rings, and give them molecular rotation according to Helmholtz’s theory of vortex motion. For stability the molecular rotation must be such as to give the same velocity at the boundary of the rotational fluid core as that of the irrotationally circulating liquid in contact with it, because, as I have proved, frictional slip between two portions of liquid in contact is inconsistent with stability. There is a further condition, upon which I cannot enter into detail just now, but which may be understood in a general way when I say that it is a condition of either uniform or of increasing molecular rotation from the surface inward, analogous to the condition that the density of a liquid, resting for example under the influence of gravity, must either be uniform or must be greater below than above for stability of equilibrium. All that I have said in favor of the model vortex gas composed of perforated solids with fluid circulations through them holds without modification for the purely hydro-kinetic model, composed of either Helmholtz cored vortex rings or of coreless vortices, and we are now troubled with no such difficulty as that of the impacts between solids. Whether, however, when the vortex theory of gases is thoroughly worked out, it will or will not be found to fail in a manner analogous to the failure which I have already pointed out in connection with the kinetic theory of gases composed of little elastic solid molecules, I cannot at present undertake to speak with certainty. It seems to me most probable that the vortex theory cannot fail in any such way, because all I have been able to find out hitherto regarding the vibration of vortices,[2] whether cored or coreless, does not seem to imply the liability of translational or impulsive energies of the individual vortices becoming lost in energy of smaller and smaller vibrations.
[Footnote 1: Investigations respecting coreless vortices will be found in a paper by the author, “Vibrations of a Columnar Vortex,” _Proc_. R.S.E., March 1, 1880; and a paper by Hicks, recently read before the Royal Society.]
[Footnote 2: See papers by the author “On Vortex Motion.” _Trans_. R.S.E. April, 1867, and “Vortex Statics,” _Proc_. R.S.E. December, 1875; also a paper by J.J. Thomson, B.A., “On the Vibrations of a Vortex Ring,” _Trans_. R.S. December, 1881, and his valuable book on “Vortex Motion.”]
As a step toward kinetic theory of matter, it is certainly most interesting to remark that in the quasi-elasticity, elasticity looking like that of an India-rubber band, which we see in a vibrating smoke-ring launched from an elliptic aperture, or in two smoke-rings which were circular, but which have become deformed from circularity by mutual collision, we have in reality a virtual elasticity in matter devoid of elasticity, and even devoid of rigidity, the virtual elasticity being due to motion, and generated by the generation of motion.
* * * * *
APPLICATION OF ELECTRICITY TO TRAMWAYS.
By M. HOLROYD SMITH.
Last year, when I had the pleasure of reading a paper before you on my new system of electric tramways, I ventured to express the hope that before twelve months had passed, “to be able to report progress,” and I am happy to say that notwithstanding the wearisome delay and time lost in fruitless negotiations, and the hundred and one difficulties within and without that have beset me, I am able to appear before you again and tell you of advance.
[Illustration: FIG. 1]
Practical men know well that there is a wide difference between a model and a full sized machine; and when I decided to construct a full sized tramcar and lay out a full sized track, I found it necessary to make many alterations of detail, my chief difficulty being so to design my work as to facilitate construction and allow of compensation for that inaccuracy of workmanship which I have come to regard as inevitable.
In order to satisfy the directors of a tramway company of the practical nature of my system before disturbing their lines, I have laid, in a field near the works of Messrs. Smith, Baker & Co., Manchester, a track 110 yards long, 4 ft. 81/2 in. gauge, and I have constructed a full sized street tramcar to run thereon. My negotiations being with a company in a town where there are no steep gradients, and where the coefficient of friction of ordinary wheels would be sufficient for all tractive purposes, I thought it better to avoid the complication involved in employing a large central wheel with a broad surface specially designed for hilly districts, and with which I had mounted a gradient of one in sixteen.
[Illustration: FIG. 2]
But as the line in question was laid with all the curves unnecessarily quick, even those in the “pass-bies,” I thought it expedient to employ differential gear, as illustrated at D, Fig. 1, which is a sketch plan showing the mechanism employed. M is a Siemens electric motor running at 650 revolutions per minute; E is a combination of box gearing, frictional clutch, and chain pinion, and from this pinion a steel chain passes around the chain-wheel, H, which is free to revolve upon the axle, and carries within it the differential pinion, gearing with the bevel-wheel, B squared, keyed upon the sleeve of the loose tram-wheel, T squared, and with the bevel-wheel, B, keyed upon the axle, to which the other tram-wheel, T, is attached. To the other tram-wheels no gear is connected; one of them is fast to the axle, and the other runs loose, but to them the brake is applied in the usual manner.
The electric current from the collector passes, by means of a copper wire, and a switch upon the dashboard of the car, and resistance coils placed under the seats, to the motor, and from the motor by means of an adjustable clip (illustrated in diagram, Fig. 2) to the axles, and by them through the four wheels to the rails, which form the return circuit.
[Illustration: FIG. 3]
I have designed many modifications of the track, but it is, perhaps, best at present to describe only that which I have in actual use, and it is illustrated in diagram, Fig. 3, which is a sectional and perspective view of the central channel. L is the surface of the road, and SS are the sleepers, CC are the chairs which hold the angle iron, AA forming the longitudinally slotted center rail and the electric lead, which consists of two half-tubes of copper insulated from the chairs by the blocks, I, I. A special brass clamp, free to slide upon the tube, is employed for this purpose, and the same form of clamp serves to join the two ends of the copper tubes together and to make electric contact. Two half-tubes instead of one slotted tube have been employed, in order to leave a free passage for dirt or wet to fall through the slot in the center rail to the drain space, G. Between chair and chair hewn granite or artificial stone is employed, formed, as shown in the drawing, to complete the surface of the road and to form a continuous channel or drain. In order that this drain may not become choked, at suitable intervals, in the length of the track, sump holes are formed as illustrated in diagram, Fig. 4 These sump holes have a well for the accumulation of mud, and are also connected with the main street drain, so that water can freely pass away. The hand holes afford facility for easily removing the dirt.
In a complete track these hand holes would occasionally be wider than shown here, for the purpose of removing or fixing the collector, Fig. 5, which consists of two sets of spirally fluted rollers free to revolve upon spindles, which are held by knuckle-joints drawn together by spiral springs; by this means the pressure of the rollers against the inside of the tube is constantly maintained, and should any obstruction occur in the tube the spiral flute causes it to revolve, thus automatically cleansing the tubes.
[Illustration: FIG. 4]
The collector is provided with two steel plates, which pass through the slit in the center rail; the lower ends of these plates are clamped by the upper frame of the collector, insulating material being interposed, and the upper ends are held in two iron cheeks. Between these steel plates insulated copper strips are held, electrically connected with the collector and with the adjustable clip mounted upon the iron cheeks; this clip holds the terminal on the end of the wire (leading to the motor) firmly enough for use, the cheeks being also provided with studs for the attachment of leather straps hooked on to the framework of the car, one for the forward and one for backward movement of the collector. These straps are strong enough for the ordinary haulage of the collector, and for the removal of pebbles and dirt that may get into the slit; but should any absolute block occur then they break and the terminal is withdrawn from the clip; the electric contact being thereby broken the car stops, the obstruction can then be removed and the collector reconnected without damage and with little delay.
[Illustration: FIG. 5]
In order to secure continuity of the center rail throughout the length of the track, and still provide for the removal of the collector at frequent intervals, the framework of the collector is so made that, by slackening the side-bolts, the steel plates can be drawn upward and the collector itself withdrawn sideways through the hand holes, one of the half-tubes being removed for the purpose.
Fig. 6 illustrates another arrangement that I have constructed, both of collector and method of collecting.
[Illustration: FIG. 6]
As before mentioned, the arrangement now described has been carried out in a field near the works of Messrs. Smith, Baker & Co., Cornbrook Telegraph Works, Manchester, and its working efficiency has been most satisfactory. After a week of rain and during drenching showers the car ran with the same speed and under the same control as when the ground was dry.
This I account for by the theory that when the rails are wet and the tubes moist the better contact made compensates for the slight leakage that may occur.
At the commencement of my paper I promised to confine myself to work done; I therefore abstain from describing various modifications of detail for the same purpose. But one method of supporting and insulating the conductor in the channel may be suggested by an illustration of the plan I adopted for a little pleasure line in the Winter Gardens, Blackpool.
[Illustration: FIG. 7.]
Fig. 7. There the track being exclusively for the electric railway, it was not necessary to provide a center channel; the conductor has therefore been placed in the center of the track, and consists of bar iron 11/4 in. by 1/2 in., and is held vertically by means of studs riveted into the side; these studs pass through porcelain insulators, and by means of wooden clamps and wedges are held in the iron chairs which rest upon the sleepers. The iron conductors were placed vertically to facilitate bending round the sharp curves which were unavoidable on this line.
The collector consists of two metal slippers held together by springs, attached to the car by straps and electrically connected to the motor by clips in the same manner as the one employed in Manchester.
I am glad to say that, notwithstanding the curves with a radius of 55 feet and gradients of 1 in 57, this line is also a practical success.
* * * * *
FIRES IN LONDON AND NEW YORK.
When the chief of the London Fire Brigade visited the United States in 1882, he was, as is the general rule on the other side of the Atlantic, “interviewed”–a custom, it may be remarked, which appears to be gaining ground also in this country. The inferences drawn from these interviews seem to be that the absence of large fires in London was chiefly due to the superiority of our fire brigade, and that the greater frequency of conflagrations in American cities, and particularly in New York, was due to the inferiority of their fire departments. How unjust such a comparison would be is shown in a paper presented by Mr. Edward B. Dorsey, a member of the American Society of Civil Engineers, to that association, in which the author discusses the comparative liability to and danger from conflagrations in London and in American cities. He found from an investigation which he conducted with much care during a visit to London that it is undoubtedly true that large fires are much less frequent in the metropolis than in American cities; but it is equally true that the circumstances existing in London and New York are quite different. As it is a well-known fact that the promptness, efficiency, and bravery of American firemen cannot be surpassed, we gladly give prominence to the result of the author’s investigations into the true causes of the great liability of American cities to large fires. In a highly interesting comparison the writer has selected New York and London as typical cities, although his observations will apply to most American and English towns, if, perhaps, with not quite the same force. In the first place, the efforts of the London Fire Brigade receive much aid from our peculiarly damp climate. From the average of eleven years (1871-1881) of the meteorological observations made at the Greenwich Observatory, it appears that in London it rains, on the average, more than three days in the week, that the sun shines only one-fourth of the time he is above the horizon, and that the atmosphere only lacks 18 per cent. of complete saturation, and is cloudy seven-tenths of the time. Moreover, the humidity of the atmosphere in London is very uniform, varying but little in the different months. Under these circumstances, wood will not be ignited very easily by sparks or by contact with a weak flame. This is very different from the condition of wood in the long, hot, dry seasons of the American continent. The average temperature for the three winter months in London is 38.24 degrees Fahr.; in New York it is 31.56 degrees, or 6.68 degrees lower. This lower range of temperature must be the cause of many conflagrations, for, to make up for the deficiency in the natural temperature, there must be in New York many more and larger domestic fires. The following statistics, taken from the records of the New York Fire Department, show this. In the three winter months of 1881, January, February, and December, there were 522 fire alarms in New York, or an average per month of 174; in the remaining nine months 1,263, or an average per month of 140. In the corresponding three winter months of 1882 there were 602 fire alarms, or an average per month of 201; in the remaining nine months 1,401, or an average per month of 155. In round numbers there were in 1881 one-fourth, and in 1882 one-third more fire alarms in the three winter months than in the nine warmer months. We are not aware that similar statistics have ever been compiled for London, and are consequently unable to draw comparison; but, speaking from recollection, fires appear to be more frequent also in London during the winter months.
Another cause of the greater frequency of fires in New York and their more destructive nature is the greater density of population in that city. The London Metropolitan Police District covers 690 square miles, extending 12 to 15 miles in every direction from Charing Cross, and contained in 1881 a population of 4,764,312; but what is generally known as London covers 122 square miles, containing, in 1881, 528,794 houses, and a population of 3,814,574, averaging 7.21 persons per house, 49 per acre, and 31,267 per square mile. Now let us look at New York. South of Fortieth Street between the Hudson and East Rivers, New York has an area of 3,905 acres, a fraction over six square miles, exclusive of piers, and contained, according to the census of 1880, a population of 813,076. This gives 208 persons per acre. The census of 1880 reports the total number of dwellings in New York at 73,684; total population, 1,206,299; average per dwelling, 16.37. Selecting for comparison an area about equal from the fifteen most densely populated districts or parishes of London, of an aggregate area of 3,896 acres, and with a total population of 746,305, we obtain 191.5 persons per acre. Thus briefly New York averaged 208 persons per acre, and 16.37 per dwelling; London, for the same area, 191.5 persons per acre, and 7.21 per house. But this comparison is scarcely fair, as in London only the most populous and poorest districts are included, corresponding to the entirely tenement districts of New York, while in the latter city it includes the richest and most fashionable sections, as well as the poorest. If tenement districts were taken alone, the population would be found much more dense, and New York proportionately much more densely populated. Taking four of the most thickly populated of the London districts (East London, Strand, Old Street, St. Luke’s, St. Giles-in-the-Fields, and St. George, Bloomsbury), we find on a total area of 792 acres a population of 197,285, or an average of 249 persons per acre. In four of the most densely populated wards of New York (10th, 11th, 13th, and 17th), we have on an area of 735 acres a population of 258,966, or 352 persons per acre. This is 40 per cent. higher than in London, the districts being about the same size, each containing about 1-1/5 square miles. Apart from the greater crowding which takes place in New York, and the different style of buildings, another very fertile cause of the spreading of fires is the freer use of wood in their construction. It is asserted that in New York there is more than double the quantity of wood used in buildings per acre than in London. From a house census undertaken in 1882 by the New York Fire Department, moreover, it appears that there were 106,885 buildings including sheds, of which 28,798 houses were built of wood or other inflammable materials, besides 3,803 wooden sheds, giving a total of 32,601 wooden buildings.
We are not aware that there are any wooden houses left in London. There are other minor causes which act as checks upon the spreading of fires in London. London houses are mostly small in size, and fires are thus confined to a limited space between brick walls. Their walls are generally low and well braced, which enable the firemen to approach them without danger. About 60 per cent. of London houses are less than 22 feet high from the pavement to the eaves; more than half of the remainder are less than 40 feet high, very few being over 50 feet high. This, of course, excludes the newer buildings in the City. St. James’s Palace does not exceed 40 feet, the Bank of England not over 30 feet in height; but these are exceptional structures. Fireproof roofings and projecting party walls also retard the spreading of conflagrations. The houses being comparatively low and small, the firemen are enabled to throw water easily over them, and to reach their roofs with short ladders. There is in London an almost universal absence of wooden additions and outbuildings, and the New York ash barrel or box kept in the house is also unknown. The local authorities in London keep a strict watch over the manufacture or storage of combustible materials in populous parts of the city. Although overhead telegraph wires are multiplying to an alarming extent in London, their number is nothing to be compared to their bewildering multitude in New York, where their presence is not only a hinderance to the operations of the firemen, but a positive danger to their lives. Finally–and this has already been partly dealt with in speaking of the comparative density of population of the two cities–a look at the map of London will show us how the River Thames and the numerous parks, squares, private grounds, wide streets, as well as the railways running into London, all act as effectual barriers to the extension of fires.
The recent great conflagrations in the city vividly illustrate to Londoners what fire could do if their metropolis were built on the New York plan. The City, however, as we have remarked, is an exceptional part of London, and, taking the British metropolis as it is, with its hundreds of square miles of suburbs, and contrasting its condition with that of New York, we are led to adopt the opinion that London, with its excellent fire brigade, is safe from a destructive conflagration. It was stated above, and it is repeated here, that the fire brigade of New York is unsurpassed for promptness, skill, and heroic intrepidity, but their task, by contrast, is a heavy one in a city like New York, with its numerous wooden buildings, wooden or asphalt roofs, buildings from four to ten stories high, with long unbraced walls, weakened by many large windows, containing more than ten times the timber an average London house does, and that very inflammable, owing to the dry and hot American climate. But this is not all. In New York we find the five and six story tenement houses with two or three families on each floor, each with their private ash barrel or box kept handy in their rooms, all striving to keep warm during the severe winters of North America. We also find narrow streets and high buildings, with nothing to arrest the extension of a fire except a few small parks, not even projecting or effectual fire-walls between the several buildings. And to all this must be added the perfect freedom with which the city authorities of New York allow in its most populous portions large stables, timber yards, carpenters’ shops, and the manufacture and storage of inflammable materials. Personal liberty could not be carried to a more dangerous extent. We ought to be thankful that in such matters individual freedom is somewhat hampered in our old-fashioned and quieter-going country.–_London Morning Post_.
* * * * *
THE LATEST KNOWLEDGE ABOUT GAPES.
The gape worm may be termed the _bete noir_ of the poultry-keeper–his greatest enemy–whether he be farmer or fancier. It is true there are some who declare that it is unknown in their poultry-yards–that they have never been troubled with it at all. These are apt to lay it down, as I saw a correspondent did in a recent number of the _Country Gentleman_, that the cause is want of cleanliness or neglect in some way. But I can vouch that that is not so. I have been in yards where everything was first-rate, where the cleanliness was almost painfully complete, where no fault in the way of neglect could be found, and yet the gapes were there; and on the other hand, I have known places where every condition seemed favorable to the development of such a disease, and there it was absent–this not in isolated cases, but in many. No, we must look elsewhere for the cause.
Observations lead me to the belief that gapes are more than usually troublesome during a wet spring or summer following a mild winter. This would tend to show that the egg from which the worm (that is in itself the disease) emerges is communicated from the ground, from the food eaten, or the water drunk, in the first instance, but it is more than possible that the insects themselves may pass from one fowl to another. All this we can accept as a settled fact, and also any description of the way in which the parasitic worms attach themselves to the throats of the birds, and cause the peculiar gaping of the mouth which gives the name to the disease.
Many remedies have been suggested, and my object now is to communicate some of the later ones–thus to give a variety of methods, so that in case of the failure of one, another will be at hand ready to be tried. It is a mistake always to pin the faith to one remedy, for the varying conditions found in fowls compel a different treatment. The old plan of dislodging the worms with a feather is well known, and need not be described again. But I may mention that in this country some have found the use of an ointment, first suggested by Mr. Lewis Wright, I believe, most valuable. This is made of mercurial ointment, two parts; pure lard, two parts; flour of sulphur, one part; crude petroleum, one part–and when mixed together is applied to the heads of the chicks as soon as they are dry after hatching. Many have testified that they have never found this to fail as a preventive, and if the success is to be attributed to the ointment, it would seem as if the insects are driven off by its presence, for the application to the heads merely would not kill the eggs.
Some time ago Lord Walsingham offered, through the Entomological Society of London, a prize for the best life history of the gapes disease, and this has been won by the eminent French scientist M. Pierre Megnin, whose essay has been published by the noble donor. His offer was in the interest of pheasant breeders, but the benefit is not confined to that variety of game alone, for it is equally applicable to all gallinaceous birds troubled with this disease. The pamphlet in question is a very valuable work, and gives very clearly the methods by which the parasite develops. But for our purpose it will be sufficient to narrate what M. Megnin recommends for the cure of it. These are various, as will be seen, and comprise the experience of other inquirers as well as himself.
He states that Montague obtained great success by a combination of the following methods: Removal from infested runs; a thorough change of food, hemp seed and green vegetables figuring largely in the diet; and for drinking, instead of plain water, an infusion of rue and garlic. And Megnin himself mentions an instance of the value of garlic. In the years 1877 and 1878, the pheasant preserves of Fontainebleau were ravaged by gapes. The disease was there arrested and totally cured, when a mixture, consisting of yolks of eggs, boiled bullock’s heart, stale bread crumbs, and leaves of nettle, well mixed and pounded together with garlic, was given, in the proportion of one clove to ten young pheasants. The birds were found to be very fond of this mixture, but great care was taken to see that the drinking vessels were properly cleaned out and refilled with clean, pure water twice a day. This treatment has met with the same success in other places, and if any of your readers are troubled with gapes and will try it, I shall be pleased to see the results narrated in the columns of the _Country Gentleman_. Garlic in this case is undoubtedly the active ingredient, and as it is volatile, when taken into the stomach the breath is charged with it, and in this way (for garlic is a powerful vermifuge) the worms are destroyed.
Another remedy recommended by M. Megnin was the strong smelling vermifuge assafoetida, known sometimes by the suggestive name of “devil’s dung.” It has one of the most disgusting oders possible, and is not very pleasant to be near. The assafoetida was mixed with an equal part of powdered yellow gentian, and this was given to the extent of about 8 grains a day in the food. As an assistance to the treatment, with the object of killing any embryos in the drinking water, fifteen grains of salicylate of soda was mixed with a pint and three-quarters of water. So successful was this, that on M. De Rothschild’s preserves at Rambouillet, where a few days before gapes were so virulent that 1,200 pheasants were found dead every morning, it succeeded in stopping the epidemic in a few days. But to complete the matter, M. Megnin adds that it is always advisable to disinfect the soil of preserves. For this purpose, the best means of destroying any eggs or embryos it may contain is to water the ground with a solution of sulphuric acid, in the proportion of a pennyweight to three pints of water, and also birds that die of the disease should be deeply buried in lime.
Fumigation with carbolic acid is an undoubted cure, but then it is a dangerous one, and unless very great care is taken in killing the worms, the bird is killed also. Thus many find this a risky method, and prefer some other. Lime is found to be a valuable remedy. In some districts of England, where lime-kilns abound, it is a common thing to take children troubled with whooping-cough there. Standing in the smoke arising from the kilns, they are compelled to breathe it. This dislodges the phlegm in the throat, and they are enabled to get rid of it. Except near lime-kilns, this cannot be done to chickens, but fine slaked lime can be used, either alone or mixed with powdered sulphur, two parts of the former to one of the latter. The air is charged with this fine powder, and the birds, breathing it, cough, and thus get rid of the worms, which are stupefied by the lime, and do not retain so firm a hold on the throat. An apparatus has recently been introduced to spread this lime powder. It is in the form of an air-fan, with a pointed nozzle, which is put just within the coop at night, when the birds are all within. The powder is already in a compartment made for it, and by the turning of a handle, it is driven through the nozzle, and the air within the coop charged with it. There is no waste of powder, nor any fear that it will not be properly distributed. Experienced pheasant and poultry breeders state that by the use of this once a week, gapes are effectually prevented. In this case, also, I shall be glad to learn the result if tried.
STEPHEN BEALE.
H—-, Eng., Aug. 1.
–_Country Gentleman_.
* * * * *
WOLPERT’S METHOD OF ESTIMATING THE AMOUNT OF CARBONIC ACID IN THE AIR.
There is a large number of processes and apparatus for estimating the amount of carbonic acid in the air. Some of them, such as those of Regnault, Reiset, the Montsouris observers (Fig. 1), and Brand, are accurate analytical instruments, and consequently quite delicate, and not easily manipulated by hygienists of middling experience. Others are less complicated, and also less exact, but still require quite a troublesome manipulation–such, for example, as the process of Pettenkofer, as modified by Fodor, that of Hesse, etc.
[Illustration: APPARATUS FOR ESTIMATING THE CARBONIC ACID OF THE AIR. FIG. 1.–Montsouris Apparatus. FIG. 2.–Smith’s Minimetric Apparatus. FIG. 3.–Bertin-Sans Apparatus. FIG. 4.–Bubbling Glass. FIG. 5.–Pipette. FIG. 6.–Arrangement of the U-shaped Tube. FIG. 7.–Wolpert’s Apparatus.]
Hygienists have for some years striven to obtain some very simple apparatus (rather as an indicator than an analytical instrument) that should permit it to be quickly ascertained whether the degree of impurity of a place was incompatible with health, and in what proportion it was so. It is from such efforts that have resulted the processes of Messrs. Smith. Lunge, Bertin-Sans, and the apparatus of Prof. Wolpert (Fig. 7).
It is of the highest interest to ascertain the proportion of carbonic acid in the air, and especially in that of inhabited places, since up to the present this is the best means of finding out how much the air that we are breathing is polluted, and whether there is sufficient ventilation or not. Experiment has, in fact, demonstrated that carbonic acid increases in the air of inhabited rooms in the same way as do those organic matters which are difficult of direct estimation. Although a few ten-thousandths more of carbonic acid in our air cannot of themselves endanger us, yet they have on another hand a baneful significance, and, indeed, the majority of hygienists will not tolerate more than six ten-millionths of this element in the air of dwellings, and some of them not more than five ten-millionths.
Carbonic acid readily betrays its presence through solutions of the alkaline earths such as baryta and chalk, in which its passage produces an insoluble carbonate, and consequently makes the liquid turbid. If, then, one has prepared a solution of baryta or lime, of which a certain volume is made turbid by the passage of a likewise known volume of CO_{2}, it will be easy to ascertain how much CO_{2} a certain air contains, from the volume of the latter that it will be necessary to pass through the basic solution in order to obtain the amount of turbidity that has been taken as a standard. The problem consists in determining the minimum of air required to make the known solution turbid. Hence the name “minimetric estimation,” that has been given to this process. Prof. Lescoeur has had the goodness to construct for me a Smith’s minimetric apparatus (Fig. 2) with the ingenious improvements that have been made in it by Mr. Fischli, assistant to Prof. Weil, of Zurich. I have employed it frequently, and I use it every year in my lectures. I find it very practical, provided one has got accustomed to using it. It is, at all events, of much simpler manipulation than that of Bertin-Sans, although the accuracy of the latter may be greater (Figs. 3, 4, 5, and 6). But it certainly has more than one defect, and some of the faults that have been found with it are quite serious. The worst of these consists in the difficulty of catching the exact moment at which the turbidity of the basic liquid is at the proper point for arresting the operation. In addition to this capital defect, it is regrettable that it is necessary to shake the flask that contains the solution after every insufflation of air, and also that the play of the valves soon becomes imperfect. Finally, Mr. Wolpert rightly sees one serious drawback to the use of baryta in an apparatus that has to be employed in schools, among children, and that is that this substance is poisonous. This gentleman therefore replaces the solution of baryta by water saturated with lime, which costs almost nothing, and the preparation of which is exceedingly simple. Moreover, it is a harmless agent.
The apparatus consists of two parts. The first of these is a glass tube closed at one end, and 12 cm. in length by 12 mm. in diameter. Its bottom is of porcelain, and bears on its inner surface the date 1882 in black characters. Above, and at the level that corresponds to a volume of three cubic centimeters, there is a black line which serves as an invariable datum point. A rubber bulb of twenty-eight cubic centimeters capacity is fixed to a tube which reaches its bottom, and is flanged at the other extremity (Fig. 7).
The operation is as follows:
The saturated, but limpid, solution of lime is poured into the first tube up to the black mark, the tube of the air bulb is introduced into the lime water in such a way that its orifice shall be in perfect contact with the bottom of the other tube, and then, while the bulb is held between the fore and middle fingers of the upturned hand, one presses slowly with the thumb upon its bottom so as to expel all the air that it contains. This air enters the lime-water bubble by bubble. After this the tube is removed from the water, and the bulb is allowed to fill with air, and the same maneuver is again gone through with. This is repeated until the figures 1882, looked at from above, cease to be clearly visible, and disappear entirely after the contents of the tube have been vigorously shaken.
The measures are such that the turbidity supervenes at once if the air in the bulb contains twenty thousandths of CO_{2}. If it becomes necessary to inject the contents of the bulb into the water twice, it is clear that the proportion is only ten thousandths; and if it requires ten injections the air contains ten times less CO_{2} than that having twenty thousandths, or only two per cent. A table that accompanies the apparatus has been constructed upon this basis, and does away with the necessity of making calculations.
An air that contained ten thousandths of CO_{2}, or even five, would be almost as deleterious, in my opinion, as one of two per cent. It is of no account, then, to know the proportions intermediate to these round numbers. Yet it is possible, if the case requires it, to obtain an indication between two consecutive figures of the scale by means of another bulb whose capacity is only half that of the preceding. Thus, two injections of the large bulb, followed by one of the small, or two and a half injections, correspond to a richness of 8 thousandths of CO_{2}; and 51/2 to 3.6 thousandths. This half-bulb serves likewise for another purpose. From the moment that the large bulb makes the lime-water turbid with an air containing two per cent. of CO_{2}, it is clear that the small one can cause the same turbidity only with air twice richer in CO_{2}, _i.e._, of four per cent.
This apparatus, although it makes no pretensions to extreme accuracy, is capable of giving valuable information. The table that accompanies it is arranged for a temperature of 17 deg. and a pressure of 740 mm. But different meteorological conditions do not materially alter the results. Thus, with 10 deg. less it would require thirty-one injections instead of thirty, and CO_{2} would be 0.64 per 1,000 instead of 0.66; and with 10 deg. more, thirty injections instead of thirty one.
The apparatus is contained in a box that likewise holds a bottle of lime-water sufficient for a dozen analyses, the table of proportions of CO_{2}, and the apparatus for cleaning the tubes. The entire affair is small enough to be carried in the pocket.–_J. Arnould, in Science et Nature_.
* * * * *
[NATURE.]
THE VOYAGE OF THE VETTOR PISANI.
Knowing how much _Nature_ is read by all the naturalists of the world, I send these few lines, which I hope will be of some interest.
The Italian R.N. corvette Vettor Pisani left Italy in April, 1882, for a voyage round the world with the ordinary commission of a man-of-war. The Minister of Marine, wishing to obtain scientific results, gave orders to form, when possible, a marine zoological collection, and to carry on surveying, deep-sea soundings, and abyssal thermometrical measurements. The officers of the ship received their different scientific charges, and Prof. Dohrn, director of the Zoological Station at Naples, gave to the writer necessary instructions for collecting and preserving sea animals.
At the end of 1882 the Vettor Pisani visited the Straits of Magellan, the Patagonian Channels, and Chonos and Chiloe islands; we surveyed the Darwin Channel, and following Dr. Cuningham’s work (who visited these places on board H.M.S. Nassau), we made a numerous collection of sea animals by dredging and fishing along the coasts.
While fishing for a big shark in the Gulf of Panama during the stay of our ship in Taboga Island, one day in February, with a dead clam, we saw several great sharks some miles from our anchorage. In a short time several boats with natives went to sea, accompanied by two of the Vettor Pisani’s boats.
Having wounded one of these animals in the lateral part of the belly, we held him with lines fixed to the spears; he then began to describe a very narrow curve, and irritated by the cries of the people that were in the boats, ran off with a moderate velocity. To the first boat, which held the lines just mentioned, the other boats were fastened, and it was a rather strange emotion to feel ourselves towed by the monster for more than three hours with a velocity that proved to be two miles per hour. One of the boats was filled with water. At last the animal was tired by the great loss of blood, and the boats assembled to haul in the lines and tow the shark on shore.
With much difficulty the nine boats towed the animal alongside the Vettor Pisani to have him hoisted on board, but it was impossible on account of his colossal dimensions. But as it was high water we went toward a sand beach with the animal, and we had him safely stranded at night.
With much care were inspected the mouth, the nostrils, the ears, and all the body, but no parasite was found. The eyes were taken out and prepared for histological study. The set of teeth was all covered by a membrane that surrounded internally the lips; the teeth are very little, and almost in a rudimental state. The mouth, instead of opening in the inferior part of the head, as in common sharks, was at the extremity of the head; the jaws having the same bend.
Cutting the animal on one side of the backbone we met (1) a compact layer of white fat 20 centimeters deep; (2) the cartilaginous ribs covered with blood vessels; (3) a stratum of flabby, stringy, white muscle, 60 centimeters high, apparently in adipose degeneracy; (4) the stomach.
By each side of the backbone he had three chamferings, or flutings, that were distinguished by inflected interstices. The color of the back was brown with yellow spots that became close and small toward the head, so as to be like marble spots. The length of the shark was 8.90 m. from the mouth to the _pinna caudalis_ extremity, the greatest circumference 6.50 m., and 2.50 m. the main diameter (the outline of the two projections is made for giving other dimensions).
The natives call the species _Tintoreva_, and the most aged of the village had only once before fished such an animal, but smaller. While the animal was on board we saw several _Remora_ about a foot long drop from his mouth; it was proved that these fish lived fixed to the palate, and one of them was pulled off and kept in the zoological collection of the ship.
The Vettor Pisani has up the present visited Gibraltar, Cape Verde Islands, Pernambuco, Rio Janeiro, Monte Video, Valparaiso, many ports of Peru, Guayaquil, Panama, Galapagos Islands, and all the collections were up to this sent to the Zoological Station at Naples to be studied by the naturalists. By this time the ship left Callao for Honolulu, Manila, Hong Kong, and, as the Challenger had not crossed the Pacific Ocean in these directions, we made several soundings and deep-sea thermometrical measurements from Callao to Honolulu. Soundings are made with a steel wire (Thompson system) and a sounding-rod invented by J. Palumbo, captain of the ship. The thermometer employed is a Negretti and Zambra deep-sea thermometer, improved by Captain Maguaghi (director of the Italian R.N. Hydrographic Office).
With the thermometer wire has always been sent down a tow-net which opens and closes automatically, also invented by Captain Palumbo. This tow-net has brought up some little animals that I think are unknown.
G. CHIERCHIA.
Honolulu July 1.
The shark captured by the Vettor Pisani in the Gulf of Panama is _Rhinodon typicus_, probably the most gigantic fish in existence. Mr. Swinburne Ward, formerly commissioner of the Seychelles, has informed me that it attains to a length of 50 feet or more, which statement was afterward confirmed by Prof. E.P. Wright. Originally described by Sir A. Smith from a single specimen which was killed in the neighborhood of Cape Town, this species proved to be of not uncommon occurrence in the Seychelles Archipelago, where it is known by the name of “Chagrin.” Quite recently Mr. Haly reported the capture of a specimen on the coast of Ceylon. Like other large sharks (_Carcharodon rondeletii, Selache maxima_, etc.), Rhinodon has a wide geographical range, and the fact of its occurrence on the Pacific coast of America, previously indicated by two sources, appears now to be fully established. T. Gill in 1865 described a large shark known in the Gulf of California by the name of “Tiburon ballenas” or whale-shark, as a distinct genus–_Micristodus punctatus_–which, in my opinion, is the same fish. And finally, Prof. W. Nation examined in 1878 a specimen captured at Callao. Of this specimen we possess in the British Museum a portion of the dental plate. The teeth differ in no respect from those of a Seychelles Chagrin; they are conical, sharply pointed, recurved, with the base of attachment swollen. Making no more than due allowance for such variations in the descriptions by different observers as are unavoidable in accounts of huge creatures examined by some in a fresh, by others in a preserved, state, we find the principal characteristics identical in all these accounts, viz.: the form of the body, head, and snout, relative measurements, position of mouth, nostrils, and eyes, dentition, peculiar ridges on the side of the trunk and tail, coloration, etc. I have only to add that this shark is stated to be of mild disposition and quite harmless. Indeed, the minute size of its teeth has led to the belief in the Seychelles that it is a herbivorous fish, which, however, is not probable.
ALBERT GUNTHER.
Natural History Museum, _July 30_.
* * * * *
THE GREELY ARCTIC EXPEDITION.
[Illustration: THE GREELY ARCTIC EXPEDITION.–THE FARTHEST POINT NORTH.]
Some account has been given of the American Meteorological Expedition, commanded by Lieutenant, now Major, Greely, of the United States Army, in the farthest north channels, beyond Smith Sound, that part of the Arctic regions where the British Polar expedition, in May, 1876, penetrated to within four hundred geographical miles of the North Pole. The American expedition, in 1883, succeeded in getting four miles beyond, this being effected by a sledge party traveling over the snow from Fort Conger, the name they had given to their huts erected on the western shore near Discovery Cove, in Lady Franklin Sound. The farthest point reached, on May 18, was in latitude 83 deg. 24 min. N.; longitude 40 deg. 46 min. W., on the Greenland coast. The sledge party was commanded by Lieutenant Lockwood, and the following particulars are supplied by Sergeant Brainerd, who accompanied Lieutenant Lockwood on the expedition. During their sojourn in the Arctic regions the men were allowed to grow the full beard, except under the mouth, where it was clipped short. They wore knitted mittens, and over these heavy seal-skin mittens were drawn, connected by a tanned seal-skin string that passed over the neck, to hold them when the hands were slipped out. Large tanned leather pockets were fastened outside the jackets, and in very severe weather jerseys were sometimes worn over the jackets for greater protection against the intense cold. On the sledge journeys the dogs were harnessed in a fan-shaped group to the traces, and were never run tandem. In traveling, the men were accustomed to hold on to the back of the sledge, never going in front of the team, and often took off their heavy overcoats and threw them on the load. When taking observations with the sextant, Lieutenant Lockwood generally reclined on the snow, while Sergeant Brainerd called time and made notes, as shown in our illustration. When further progress northward was barred by open water, and the party almost miraculously escaped drifting into the Polar sea, Lieutenant Lockwood erected, at the highest point of latitude reached by civilized man, a pyramidal-shaped cache of stones, six feet square at the base, and eight or nine feet high. In a little chamber about a foot square half-way to the apex, and extending to the center of the pile, he placed a self-recording spirit thermometer, a small tin cylinder containing records of the expedition, and then sealed up the aperture with a closely fitting stone. The cache was surmounted with a small American flag made by Mrs. Greely, but there were only thirteen stars, the number of the old revolutionary flag. From the summit of Lockwood Island, the scene presented in our illustration, 2,000 feet above the sea, Lieutenant Lockwood was unable to make out any land to the north or the northwest. “The awful panorama of the Arctic which their elevation spread out before them made a profound impression upon the explorers. The exultation which was natural to the achievement which they found they had accomplished was tempered by the reflections inspired by the sublime desolation of that stern and silent coast and the menace of its unbroken solitude. Beyond to the eastward was the interminable defiance of the unexplored coast–black, cold, and repellent. Below them lay the Arctic Ocean, buried beneath frozen chaos. No words can describe the confusion of this sea of ice–the hopeless asperity of it, the weariness of its torn and tortured surface. Only at the remote horizon did distance and the fallen snow mitigate its roughness and soften its outlines; and beyond it, in the yet unattainable recesses of the great circle, they looked toward the Pole itself. It was a wonderful sight, never to be forgotten, and in some degree a realization of the picture that astronomers conjure to themselves when the moon is nearly full, and they look down into the great plain which is called the Ocean of Storms, and watch the shadows of sterile and airless peaks follow a slow procession across its silver surface.”–_Illustrated London News_.
* * * * *
THE NILE EXPEDITION.
[Illustration: WHALER GIG FOR THE NILE.]
As soon as the authorities had finally made up their minds to send a flotilla of boats to Cairo for the relief of Khartoum, not a moment was lost in issuing orders to the different shipbuilding contractors for the completion, with the utmost dispatch, of the 400 “whaler-gigs” for service on the Nile. They are light-looking boats, built of white pine, and weigh each about 920 lb., that is without the gear, and are supposed to carry four tons of provisions, ammunition, and camp appliances, the food being sufficient for 100 days. The crew will number twelve men, soldiers and sailors, the former rowing, while the latter (two) will attend the helm. Each boat will be fitted with two lug sails, which can be worked reefed, so as to permit an awning to be fitted underneath for protection to the men from the sun. As is well known, the wind blows for two or three months alternately up and down the Nile, and the authorities expect the flotilla will have the advantage of a fair wind astern for four or five days at the least. On approaching the Cataracts, the boats will be transported on wooden rollers over the sand to the next level for relaunching.
* * * * *
THE PROPER TIME FOR CUTTING TIMBER.
_To the Editor of the Oregonian:_
Believing that any ideas relating to this matter will be of some interest to your readers in this heavily-timbered region, I therefore propose giving you my opinion and conclusions arrived at after having experimented upon the cutting and use of timber for various purposes for a number of years here upon the Pacific coast.
This, we are all well aware, is a very important question, and one very difficult to answer, since it requires observation and experiment through a course of many years to arrive at any definite conclusion; and it is a question too upon which even at the present day there exists a great difference of opinion among men who, being engaged in the lumber business, are thereby the better qualified to form an opinion.
Many articles have been published in the various papers of the country upon this question for the past thirty years, but in all cases an opinion only has been given, which, at the present day, such is the advance and higher development of the intellectual faculties of man, that a mere opinion upon any question without sufficient and substantial reasons to back it is of little value.
My object in writing this is not simply to give an opinion, but how and the methods used by which I adopted such conclusions, as well also as the reasons why timber is more durable and better when cut at a certain season of the year than when cut at any other.
In the course of my investigations of this question for the past thirty years, I have asked the opinion of a great many persons who have been engaged in the lumber business in various States of the Union, from Maine to Wisconsin, and they all agree upon one point, viz., that the winter time is the proper time for cutting timber, although none has ever been able to give a reason why, only the fact that such was the case, and therefore drawing the inference that it was the proper time when timber should be cut; and so it is, for one reason only, however, and that is the convenience for handling or moving timber upon the snow and ice.
It was while engaged in the business of mining in the mountains of California in early days, and having occasion to work often among timber, in removing stumps, etc., it was while so engaged that I noticed one peculiar fact, which was this–that the stumps of some trees which had been cut but two or three years had decayed, while others of the same size and variety of pine which had been cut the same year were as sound and firm as when first cut. This seemed strange to me, and I found upon inquiry of old lumbermen who had worked among timber all their lives, that it was strange to them also, and they could offer no explanation; and it was the investigation of this singular fact that led me to experiment further upon the problem of cutting timber.
It was not, however, until many years after, and when engaged in clearing land for farming purposes, that I made the discovery why some stumps should decay sooner than others of the same size and variety, even when cut a few months afterward.
I had occasion to clear several acres of land which was covered with a very dense growth of young pines from two to six inches in diameter (this work for certain reasons is usually done in the winter). The young trees, not being suitable for fuel, are thrown into piles and burned upon the ground. Such land, therefore, on account of the stumps is very difficult to plow, as the stumps do not decay for three or four years, while most of the larger ones remain sound even longer.
But, for the purpose of experimenting, I cleaned a few acres of ground in the spring, cutting them in May and June. I trimmed the poles, leaving them upon the ground, and when seasoned hauled them to the house for fuel, and found that for cooking or heating purposes they were almost equal to oak; and it was my practice for many years afterward to cut these young pines in May or June for winter fuel.
I found also that the stumps, instead of remaining sound for any length of time, decayed so quickly that they could all be plowed up the following spring.
From which facts I draw these conclusions: that if in the cutting of timber the main object is to preserve the stumps, cut your trees in the fall or winter; but if the value of the timber is any consideration, cut your trees in the spring after the sap has ascended the tree, but before any growth has taken place or new wood has been formed.
I experimented for many years also in the cutting of timber for fencing, fence posts, etc., and with the same results. Those which were cut in the spring and set after being seasoned were the most durable, such timber being much lighter, tougher, and in all respects better for all variety of purposes.
Having given some little idea of the manner in which I experimented, and the conclusions arrived at as to the proper time when timber should be cut, I now propose to give what are, in my opinion, the reasons why timber cut in early summer is much better, being lighter, tougher and more durable than if cut at any other time. Therefore, in order to do this it is necessary first to explain the nature and value of the sap and the growth of a tree.
We find it to be the general opinion at present, as it perhaps has always been among lumbermen and those who work among timber, that the sap of a tree is an evil which must be avoided if possible, for it is this which causes decay and destroys the life and good qualities of all wood when allowed to remain in it for an unusual length of time, but that this is a mistaken idea I will endeavor to show, not that the decay is due to the sap, but to the time when the tree was felled.
We find by experiment in evaporating a quantity of sap of the pine, that it is water holding in solution a substance of a gummy nature, being composed of albumen and other elementary matters, which is deposited within the pores of the wood from the new growth of the tree; that these substances in solution, which constitute the sap, and which promote the growth of the tree, should have a tendency to cause decay of the wood is an impossibility. The injury results from the water only, and the improper time of felling the tree.
Of the process in which the sap promotes the growth of the tree, the scientist informs us that it is extracted from the soil, and flows up through the pores of the wood of the tree, where it is deposited upon the fiber, and by a peculiar process of nature the albumen forms new cells, which in process of formation crowd and push out from the center, thus constituting the growth of the tree in all directions from center to circumference. Consequently this new growth of wood, being composed principally of albumen, is of a soft, spongy nature, and under the proper conditions will decay very rapidly, which can be easily demonstrated by experiment.
Hence, we must infer that the proper time for felling the tree is when the conditions are such that the rapid decay of a new growth of wood is impossible; and this I have found by experiment to be in early summer, after the sap has ascended the tree, but before any new growth of wood has been formed. The new growth of the previous season is now well matured, has become hard and firm, and will not decay. On the contrary, the tree being cut when such new growth has not well matured, decay soon takes place, and the value of the timber is destroyed. The effect of this cutting and use of timber under the wrong conditions can be seen all around us. In the timbers of the bridges, in the trestlework and ties of railroads and in the piling of the wharves will be found portions showing rapid decay, while other portions are yet firm and in sound condition.
Much more might be said in the explanation of this subject, but not wishing to extend the subject to an improper length, I will close. I would, however, say in conclusion that persons who have the opportunities and the inclination can verify the truth of a portion, at least, of what I have stated, in a simple manner and in a short time; for instance, by cutting two or three young fir or spruce saplings, say about six inches in diameter, mark them when cut, and also mark the stumps by driving pegs marked to correspond with the trees. Continue this monthly for the space of about one year, and note the difference in the wood, which should be left out and exposed to the weather until seasoned.
C.W. HASKINS.
* * * * *
RAISING FERNS FROM SPORES.
[Illustration: 1, PAN; 2, BELL GLASS; 3, SMALL POTS AND LABELS.]
This plan, of which I give a sketch, has been in use by myself for many years, and most successfully. I have at various times given it to growers, but still I hear of difficulties. Procure a good sized bell-glass and an earthenware pan without any holes for drainage. Prepare a number of small pots, all filled for sowing, place them inside the pan, and fit the glass over them, so that it takes all in easily. Take these filled small pots out of the pan, place them on the ground, and well water them with boiling water to destroy all animal and vegetable life, and allow them to get perfectly cold; use a fine rose. Then taking each small pot separately, sow the spores on the surface and label them; do this with the whole number, and then place them in the pan under the bell-glass. This had better be done in a room, so that nothing foreign can grow inside. Having arranged the pots and placed the glass over them, and which should fit down upon the pan with ease, take a clean sponge, and tearing it up pack the pieces round the outside of the glass, and touching the inner side of the pan all round. Water this with cold water, so that the sponge is saturated. Do this whenever required, and always use water that has been boiled. At the end of six weeks or so the prothallus will perhaps appear, certainly in a week or two more; perhaps from unforeseen circumstances not for three months. Slowly these will begin to show themselves as young ferns, and most interesting it is to watch the results. As the ferns are gradually increasing in size pass a small piece of slate under the edge of the bell-glass to admit air, and do this by very careful degrees, allowing more and more air to reach them. Never water overhead until the seedlings are acclimated and have perfect form as ferns, and even then water at the edges of the pots. In due time carefully prick out, and the task so interesting to watch is performed.–_The Garden_.
* * * * *
THE LIFE HISTORY OF VAUCHERIA.
[Footnote: Read before the San Francisco Microscopical Society, August 13, and furnished for publication in the _Press_.]
By A.H. BRECKENFELD.
Nearly a century ago, Vaucher, the celebrated Genevan botanist, described a fresh water filamentous alga which he named _Ectosperma geminata_, with a correctness that appears truly remarkable when the imperfect means of observation at his command are taken into consideration. His pupil, De Candolle, who afterward became so eminent a worker in the same field, when preparing his “Flora of France,” in 1805, proposed the name of _Vaucheria_ for the genus, in commemoration of the meritorious work of its first investigator. On March 12, 1826, Unger made the first recorded observation of the formation and liberation of the terminal or non-sexual spores of this plant. Hassall, the able English botanist, made it the subject of extended study while preparing his fine work entitled “A History of the British Fresh Water Algae,” published in 1845. He has given us a very graphic description of the phenomenon first observed by Unger. In 1856 Pringsheim described the true sexual propagation by oospores, with such minuteness and accuracy that our knowledge of the plant can scarcely be said to have essentially increased since that time.
[Illustration: GROWTH OF THE ALGA, VAUCHERIA, UNDER THE MICROSCOPE.]
_Vaucheria_ has two or three rather doubtful marine species assigned to it by Harvey, but the fresh water forms are by far the more numerous, and it is to some of these I would call your attention for a few moments this evening. The plant grows in densely interwoven tufts, these being of a vivid green color, while the plant is in the actively vegetative condition, changing to a duller tint as it advances to maturity. Its habitat (with the exceptions above noted) is in freshwater–usually in ditches or slowly running streams. I have found it at pretty much all seasons of the year, in the stretch of boggy ground in the Presidio, bordering the road to Fort Point. The filaments attain a length of several inches when fully developed, and are of an average diameter of 1/250 (0.004) inch. They branch but sparingly, or not at all, and are characterized by consisting of a single long tube or cell, not divided by septa, as in the case of the great majority of the filamentous algae. These tubular filaments are composed of a nearly transparent cellulose wall, including an inner layer thickly studded with bright green granules of chlorophyl. This inner layer is ordinarily not noticeable, but it retracts from the outer envelope when subjected to the action of certain reagents, or when immersed in a fluid differing in density from water, and it then becomes distinctly visible, as may be seen in the engraving (Fig. 1). The plant grows rapidly and is endowed with much vitality, for it resists changes of temperature to a remarkable degree. _Vaucheria_ affords a choice hunting ground to the microscopist, for its tangled masses are the home of numberless infusoria, rotifers, and the minuter crustacea, while the filaments more advanced in age are usually thickly incrusted with diatoms. Here, too, is a favorite haunt of the beautiful zoophytes, _Hydra vividis_ and _H. vulgaris_, whose delicate tentacles may be seen gracefully waving in nearly every gathering.
REPRODUCTION IN VAUCHERIA.
After the plant has attained a certain stage in its growth, if it be attentively watched, a marked change will be observed near the ends of the filaments. The chlorophyl appears to assume a darker hue, and the granules become more densely crowded. This appearance increases until the extremity of the tube appears almost swollen. Soon the densely congregated granules at the extreme end will be seen to separate from the endochrome of the filament, a clear space sometimes, but not always, marking the point of division. Here a septum or membrane appears, thus forming a cell whose length is about three or four times its width, and whose walls completely inclose the dark green mass of crowded granules (Fig. 1, b). These contents are now gradually forming themselves into the spore or “gonidium,” as Carpenter calls it, in distinction from the true sexual spores, which he terms “oospores.” At the extreme end of the filament (which is obtusely conical in shape) the chlorophyl grains retract from the old cellulose wall, leaving a very evident clear space. In a less noticeable degree, this is also the case in the other parts of the circumference of the cell, and, apparently, the granular contents have secreted a separate envelope entirely distinct from the parent filament. The grand climax is now rapidly approaching. The contents of the cell near its base are now so densely clustered as to appear nearly black (Fig. 1, c), while the upper half is of a much lighter hue and the separate granules are there easily distinguished, and, if very closely watched, show an almost imperceptible motion. The old cellulose wall shows signs of great tension, its conical extremity rounding out under the slowly increasing pressure from within. Suddenly it gives way at the apex. At the same instant, the inclosed gonidium (for it is now seen to be fully formed) acquires a rotary motion, at first slow, but gradually increasing until it has gained considerable velocity. Its upper portion is slowly twisted through the opening in the apex of the parent wall, the granular contents of the lower end flowing into the extruded portion in a manner reminding one of the flow of protoplasm in a living amoeba. The old cell wall seems to offer considerable resistance to the escape of the gonidium, for the latter, which displays remarkable elasticity, is pinched nearly in two while forcing its way through, assuming an hour glass shape when about half out. The rapid rotation of the spore continues during the process of emerging, and after about a minute it has fully freed itself (Fig 1, a). It immediately assumes the form of an ellipse or oval, and darts off with great speed, revolving on its major axis as it does so. Its contents are nearly all massed in the posterior half, the comparatively clear portion invariably pointing in advance. When it meets an obstacle, it partially flattens itself against it, then turns aside and spins off in a new direction. This erratic motion is continued for usually seven or eight minutes. The longest duration I have yet observed was a little over nine and one-half minutes. Hassall records a case where it continued for nineteen minutes. The time, however, varies greatly, as in some cases the motion ceases almost as soon as the spore is liberated, while in open water, unretarded by the cover glass or other obstacles, its movements have been seen to continue for over two hours.
The motile force is imparted to the gonidium by dense rows of waving cilia with which it is completely surrounded. Owing to their rapid vibration, it is almost impossible to distinguish them while the spore is in active motion, but their effect is very plainly seen on adding colored pigment particles to the water. By subjecting the cilia to the action of iodine, their motion is arrested, they are stained brown, and become very plainly visible.
After the gonidium comes gradually to a rest its cilia soon disappear, it becomes perfectly globular in shape, the inclosed granules distribute themselves evenly throughout its interior, and after a few hours it germinates by throwing out one, two, or sometimes three tubular prolongations, which become precisely like the parent filament (Fig 2).
Eminent English authorities have advanced the theory that the ciliated gonidium of _Vaucheria_ is in reality a densely crowded aggregation of biciliated zoospores, similar to those found in many other confervoid algae. Although this has by no means been proved, yet I cannot help calling the attention of the members of this society to a fact which I think strongly bears out the said theory: While watching a gathering of _Vaucheria_ one morning when the plant was in the gonidia-forming condition (which is usually assumed a few hours after daybreak), I observed one filament, near the end of which a septum had formed precisely as in the case of ordinary filaments about to develop a spore. But, instead of the terminal cell being filled with the usual densely crowded cluster of dark green granules constituting the rapidly forming spore, it contained hundreds of actively moving, nearly transparent zoospores, _and nothing else_. Not a single chlorophyl granule was to be seen. It is also to be noted as a significant fact, that the cellulose wall was _intact_ at the apex, instead of showing the opening through which in ordinary cases the gonidium escapes. It would seem to be a reasonable inference, I think, based upon the theory above stated, that in this case the newly formed gonidium, unable to escape from its prison by reason of the abnormal strength of the cell wall, became after a while resolved into its component zoospores.
WONDERS OF REPRODUCTION.
I very much regret that my descriptive powers are not equal to conveying a sufficient idea of the intensely absorbing interest possessed by this wonderful process of spore formation. I shall never forget the bright sunny morning when for the first time I witnessed the entire process under the microscope, and for over four hours scarcely moved my eyes from the tube. To a thoughtful observer I doubt if there is anything in the whole range of microscopy to exceed this phenomenon in point of startling interest. No wonder that its first observer published his researches under the caption of “The Plant at the Moment of becoming an Animal.”
FORMATION OF OTHER SPORES.
The process of spore formation just described, it will be seen, is entirely non-sexual, being simply a vegetative process, analogous to the budding of higher plants, and the fission of some of the lower plants and animals. _Vaucheria_ has, however, a second and far higher mode of reproduction, viz., by means of fertilized cells, the true oospores, which, lying dormant as resting spores during the winter, are endowed with new life by the rejuvenating influences of spring. Their formation may be briefly described as follows:
When _Vaucheria_ has reached the proper stage in its life cycle, slight swellings appear here and there on the sides of the filament. Each of these slowly develops into a shape resembling a strongly curved horn. This becomes the organ termed the _antheridium_, from its analogy in function to the anther of flowering plants. While this is in process of growth, peculiar oval capsules or sporangia (usually 2 to 5 in number) are formed in close proximity to the antheridium. In some species both these organs are sessile on the main filament, in others they appear on a short pedicel (Figs. 3 and 4). The upper part of the antheridium becomes separated from the parent stem by a septum, and its contents are converted into ciliated motile antherozoids. The adjacent sporangia also become cut off by septa, and the investing membrane, when mature, opens: it a beak-like prolongation, thus permitting the inclosed densely congregated green granules to be penetrated by the antherozoids which swarm from the antheridium at the same time. After being thus fertilized the contents of the sporangium acquire a peculiar oily appearance, of a beautiful emerald color, an exceedingly tough but transparent envelope is secreted, and thus is constituted the fully developed oospore, the beginner of a new generation of the plant. After the production of this oospore the parent filament gradually loses its vitality and slowly decays.
The spore being thus liberated, sinks to the bottom. Its brilliant hue has faded and changed to a reddish brown, but after a rest of about three months (according to Pringsheim, who seems to be the only one who has ever followed the process of oospore formation entirely through), the spore suddenly assumes its original vivid hue and germinates into a young _Vaucheria_.
CHARM OF MICROSCOPICAL STUDY.
This concludes the account of my very imperfect attempt to trace the life history of a lowly plant. Its study has been to me a source of ever increasing pleasure, and has again demonstrated how our favorite instrument reveals phenomena of most absorbing interest in directions where the unaided eye finds but little promise. In walking along the banks of the little stream, where, half concealed by more pretentious plants, our humble _Vaucheria_ grows, the average passer by, if he notices it at all, sees but a tangled tuft of dark green “scum.” Yet, when this is examined under the magic tube, a crystal cylinder, closely set with sparkling emeralds, is revealed. And although so transparent, so apparently simple in structure that it does not seem possible for even the finest details to escape our search, yet almost as we watch it mystic changes appear. We see the bright green granules, impelled by an unseen force, separate and rearrange themselves in new formations. Strange outgrowths from the parent filament appear. The strange power we call “life,” doubly mysterious when manifested in an organism so simple as this, so open to our search, seems to challenge us to discover its secret, and, armed with our glittering lenses and our flashing stands of exquisite workmanship, we search intently, but in vain. And yet _not_ in vain, for we are more than recompensed by the wondrous revelations beheld and the unalloyed pleasures enjoyed, through the study of even the unpretentious _Vaucheria_.
The amplification of the objects in the engravings is about 80 diameters.
* * * * *
JAPANESE CAMPHOR–ITS PREPARATION, EXPERIMENTS, AND ANALYSIS OF THE CAMPHOR OIL.
[Footnote: From the Journal of the Society of Chemical Industry.]
By H. OISHI. (Communicated by Kakamatsa.)
LAURUS CAMPHORA, or “kusunoki,” as it is called in Japan, grows mainly in those provinces in the islands Shikobu and Kinshin, which have the southern sea coast. It also grows abundantly in the province of Kishu.
The amount of camphor varies according to the age of the tree. That of a hundred years old is tolerably rich in camphor. In order to extract the camphor, such a tree is selected; the trunk and large stems are cut into small pieces, and subjected to distillation with steam.
An iron boiler of 3 feet in diameter is placed over a small furnace, the boiler being provided with an iron flange at the top. Over this flange a wooden tub is placed, which is somewhat narrowed at the top, being 1 foot 6 inches in the upper, and 2 feet 10 inches in the lower diameter, and 4 feet in height. The tub has a false bottom for the passage of steam from the boiler beneath. The upper part of the tub is connected with a condensing apparatus by means of a wooden or bamboo pipe. The condenser is a flat rectangular wooden vessel, which is surrounded with another one containing cold water. Over the first is placed still another trough of the same dimensions, into which water is supplied to cool the vessel at the top. After the first trough has been filled with water, the latter flows into the next by means of a small pipe attached to it. In order to expose a large surface to the vapors, the condensing trough is fitted internally with a number of vertical partitions, which are open at alternate ends, so that the vapors may travel along the partitions in the trough from one end to the other. The boiler is filled with water, and 120 kilogrammes of chopped pieces of wood are introduced into the tub, which is then closed with a cover, cemented with clay, so as to make it air-tight. Firing is then begun; the steam passes into the tub, and thus carries the vapors of camphor and oil into the condenser, in which the camphor solidifies, and is mixed with the oil and condensed water. After twenty-four hours the charge is taken out from the tub, and new pieces of the wood are introduced, and distillation is conducted as before. The water in the boiler must be supplied from time to time. The exhausted wood is dried and used as fuel. The camphor and oil accumulated in the trough are taken out in five or ten days, and they are separated from each other by filtration. The yield of the camphor and oil varies greatly in different seasons. Thus much more solid camphor is obtained in winter than in summer, while the reverse is the case with the oil. In summer, from 120 kilogrammes of the wood 2.4 kilogrammes, or 2 per cent. of the solid camphor are obtained in one day, while in winter, from the same amount of the wood, 3 kilogrammes, or 2.5 per cent., of camphor are obtainable at the same time.
The amount of the oil obtained in ten days, _i.e._, from 10 charges or 1,200 kilogrammes of the wood, in summer is about 18 liters, while in winter it amounts only to 5-7 liters. The price of the solid camphor is at present about 1s. 1d. per kilo.
The oil contains a considerable amount of camphor in solution, which is separated by a simple distillation and cooling. By this means about 20 per cent. of the camphor can be obtained from the oil. The author subjected the original oil to fractioned distillation, and examined different fractions separately. That part of the oil which distilled between 180 deg.-185 deg. O. was analyzed after repeated distillations. The following is the result:
Found. Calculated as
C_{10}H_{16}O.
C = 78.87 78.95
H = 10.73 10.52
O = 10.40 (by difference) 10.52
The composition thus nearly agrees with that of the ordinary camphor.
The fraction between 178 deg.-180 deg. C., after three distillations, gave the following analytical result:
C = 86.95
H = 12.28
—–
99.23
It appears from this result that the body is a hydrocarbon. The vapor density was then determined by V. Meyer’s apparatus, and was found to be 5.7 (air=1). The molecular weight of the compound is therefore 5.7 x 14.42 x 2 = 164.4, which gives
H = (164.4 x 12.28)/100 = 20.18
or C_{12}H_{20}
C = (164.4 x 86.95)/100 = 11.81
Hence it is a hydrocarbon of the terpene series, having the general formula C^{n}H^(2n-4). From the above experiments it seems to be probable that the camphor oil is a complicated mixture, consisting of hydrocarbons of terpene series, oxy-hydrocarbons isomeric with camphor, and other oxidized hydrocarbons.
_Application of the Camphor Oil_.
The distinguishing property of the camphor oil, that it dissolves many resins, and mixes with drying oils, finds its application for the preparation of varnish. The author has succeeded in preparing various varnishes with the camphor oil, mixed with different resins and oils. Lampblack was also prepared by the author, by subjecting the camphor oil to incomplete combustion. In this way from 100 c.c. of the oil, about 13 grammes of soot of a very good quality were obtained. Soot or lampblack is a very important material in Japan for making inks, paints, etc. If the manufacture of lampblack from the cheap camphor oil is conducted on a large scale, it would no doubt be profitable. The following is the report on the amount of the annual production of camphor in the province of Tosa up to 1880:
Amount of Camphor produced. Total Cost.
1877………. 504,000 kins…. 65,520 yen. 1878………. 519,000 ” …. 72,660 “
1879………. 292,890 ” …. 74,481 ” 1880………. 192,837 ” …. 58,302 “
(1 yen = 2_s_. 9_d_.)
(1 kin = 1-1/3lb.)
* * * * *
THE SUNSHINE RECORDER.
McLeod’s sunshine recorder consists of a camera fixed with its axis parallel to that of the earth, and with the lens northward. Opposite to the lens there is placed a round-bottomed flask, silvered inside. The solar rays reflected from this sphere pass through the lens, and act on the sensitive surface.
[Illustration]
The construction of the instrument is illustrated by the subjoined cut, A being a camera supported at an inclination of 56 degrees with the horizon, and B the spherical flask silvered inside, while at D is placed the ferro-prussiate paper destined to receive the solar impression. The dotted line, C, may represent the direction of the central solar ray at one particular time, and it is easy to see how the sunlight reflected from the flask always passes through the lens. As the sun moves (apparently) in a circle round the flask, the image formed by the lens moves round on the sensitive paper, forming an arc of a circle.
Although it is obvious that any sensitive surface might be used in the McLeod sunshine recorder, the inventor prefers at present to use the ordinary ferro-prussiate paper as employed by engineers for copying tracings, as this paper can be kept for a considerable length of time without change, and the blue image is fixed by mere washing in water; another advantage is the circumstance that a scale or set of datum lines can be readily printed on the paper from an engraved block, and if the printed papers be made to register properly in the camera, the records obtained will show at a glance the time at which sunshine commenced and ceased.
Instead of specially silvering a flask inside, it will be found convenient to make use of one of the silvered globes which are sold as Christmas tree ornaments.
The sensitive fluid for preparing the ferro-prussiate paper is made as follows: One part by weight of ferricyanide of potassium (red prussiate) is dissolved in eight parts of water, and one part of ammonia-citrate of iron is added. This last addition must be made in the dark-room. A smooth-faced paper is now floated on the liquid and allowed to dry.–_Photo. News._
* * * * *
BREAKING OF A WATER MAIN.
In Boston, Mass., recently, at a point where two iron bridges, with stone abutments, are being built over the Boston and Albany Railroad tracks at Brookline Avenue, the main water pipe, which partially supplies the city with water, had to be raised, and while in that position a large stone which was being raised slipped upon the pipe and broke it. Immediately a stream of water fifteen feet high spurted out. Before the water could be shut off it had made a breach thirty feet long in the main line of track, so that the entire four tracks, sleepers, and roadbed at that point were washed completely away.
* * * * *
A catalogue, containing brief notices of many important scientific papers heretofore published in the SUPPLEMENT, may be had gratis at this office.
* * * * *
THE SCIENTIFIC AMERICAN SUPPLEMENT.
PUBLISHED WEEKLY.
Terms of Subscription, $5 a Year.
Sent by mail, postage prepaid, to subscribers in any part of the United States or Canada. Six dollars a year, sent, prepaid, to any foreign country.
All the back numbers of THE SUPPLEMENT, from the commencement, January 1, 1876, can be had. Price, 10 cents each.
All the back volumes of THE SUPPLEMENT can likewise be supplied. Two volumes are issued yearly. Price of each volume, $2.50, stitched in paper, or $3.50, bound in stiff covers.
COMBINED RATES–One copy of SCIENTIFIC AMERICAN and one copy of SCIENTIFIC AMERICAN SUPPLEMENT, one year, postpaid, $7.00.
A liberal discount to booksellers, news agents, and canvassers.
MUNN & CO., PUBLISHERS,
361 BROADWAY, NEW YORK, N.Y.
* * * * *
PATENTS.
In connection with the SCIENTIFIC AMERICAN, Messrs. MUNN & Co. are Solicitors of American and Foreign Patents, have had 39 years’ experience, and now have the largest establishment in the world. Patents are obtained on the best terms.
A special notice is made in the SCIENTIFIC AMERICAN of all Inventions patented through this Agency, with the name and residence of the Patentee. By the immense circulation thus given, public attention is directed to the merits of the new patent, and sales or introduction often easily effected.
Any person who has made a new discovery or invention can ascertain, free of charge, whether a patent can probably be obtained, by writing to MUNN & Co.
We also send free our Hand Book about the Patent Laws, Patents, Caveats. Trade Marks, their costs, and how procured, with hints for procuring advances on inventions. Address
MUNN & CO., 361 BROADWAY, NEW YORK.
Branch Office, cor. F and 7th Sts., Washington, D.C.