electricity and light have been discovered, and at the present time they are tumbling in in great numbers.
It was found by Faraday that many other transparent media besides heavy glass would show the phenomenon if placed between the poles, only in a less degree; and the very important observation that air itself exhibits the same phenomenon, though to an exceedingly small extent, has just been made by Kundt and Rontgen in Germany.
Dr. Kerr, of Glasgow, has extended the result to opaque bodies, and has shown that if light be passed through magnetized _iron_ its plane is rotated. The film of iron must be exceedingly thin, because of its opacity, and hence, though the intrinsic rotating power of iron is undoubtedly very great, the observed rotation is exceedingly small and difficult to observe; and it is only by a very remarkable patience and care and ingenuity that Dr. Kerr has obtained his result. Mr. Fitzgerald, of Dublin, has examined the question mathematically, and has shown that Maxwell’s theory would have enabled Dr. Kerr’s result to be predicted.
Another requirement of the theory is that bodies which are transparent to light must be insulators or non-conductors of electricity, and that conductors of electricity are necessarily opaque to light. Simple observation amply confirms this; metals are the best conductors, and are the most opaque bodies known. Insulators such as glass and crystals are transparent whenever they are sufficiently homogeneous, and the very remarkable researches of Prof. Graham Bell in the last few months have shown that even _ebonite_, one of the most opaque insulators to ordinary vision, is certainly transparent to some kinds of radiation, and transparent to no small degree.
[The reason why transparent bodies must insulate, and why conductors must be opaque, was here illustrated by mechanical models.]
A further consequence of the theory is that the velocity of light in a transparent medium will be affected by its electrical strain constant; in other words, that its refractive index will bear some close but not yet quite ascertained relation to its specific inductive capacity. Experiment has partially confirmed this, but the confirmation is as yet very incomplete. But there are a number of results not predicted by theory, and whose connection with the theory is not clearly made out. We have the fact that light falling on the platinum electrode of a voltameter generates a current, first observed, I think, by Sir W. R. Grove–at any rate, it is mentioned in his “Correlation of Forces”–extended by Becquerel and Robert Sabine to other substances, and now being extended to fluorescent and other bodies by Prof. Minchin. And finally–for I must be brief–we have the remarkable action of light on selenium. This fact was discovered accidentally by an assistant in the laboratory of Mr. Willoughby Smith, who noticed that a piece of selenium conducted electricity very much better when light was falling upon it than when it was in the dark. The light of a candle is sufficient, and instantaneously brings down the resistance to something like one-fifth of its original value.
I could show you these effects, but there is not much to see; it is an intensely interesting phenomenon, but its external manifestation is not striking–any more than Faraday’s heavy glass experiment was.
This is the phenomenon which, as you know, has been utilized by Prof. Graham Bell in that most ingenious and striking invention, the photophone. By the kindness of Prof. Silvanus Thompson, I have a few slides to show the principle of the invention, and Mr. Shelford Bidwell has been kind enough to lend me his home-made photophone, which answers exceedingly well for short distances.
I have now trespassed long enough upon your patience, but I must just allude to what may very likely be the next striking popular discovery; and that is the transmission of light by electricity; I mean the transmission of such things as views and pictures by means of the electric wire. It has not yet been done, but it seems already theoretically possible, and it may very soon be practically accomplished.
* * * * *
INTERESTING ELECTRICAL RESEARCHES.
During the last six years Dr. Warren de la Rue has been investigating, in conjunction with Dr. Hugo Muller, the various and highly interesting phenomena which accompany the electric discharge. From time to time the results of their researches were communicated to the Royal Society, and appeared in its Proceedings. Early last year Dr. De la Rue being requested to bring the subject before the members of the Royal Institution, acceded to the pressing invitation of his colleagues and scientific friends. The discourse, which was necessarily long postponed on account of the preparations that had to be made, was finally given on Friday, the 21st of January, and was one of the most remarkable, from the elaborate nature of the experiments, ever delivered in the theater of that deservedly famous institution.
Owing to the great inconvenience of removing the battery from his laboratory, Dr. de la Rue, despite the great expenditure, directed Mr. S. Tisley to prepare, expressly for the lecture, a second series of 14,400 cells, and fit it up in the basement of the Royal Institution. The construction of this new battery occupied Mr. Tisley a whole year, while the charging of it extended over a fortnight.
The “de la Rue cell,” if we may so call one of these elements, consists of a zinc rod, the lower portion of which is embedded in a solid electrolyte, viz., chloride of silver, with which are connected two flattened silver wires to serve as electrodes. When these are united and the silver chloride moistened, chemical action begins, and a weak but constant current is generated.
The electromotive force of such a cell is 1.03 volts, and a current equivalent to one volt passing through a resistance of one ohm was found to decompose 0.00146 grain of water in one second. The battery is divided into “cabinets,” which hold from 1,200 to 2,160 small elements each. This facilitates removal, and also the detection of any fault that may occur.
It will be remembered that in 1808 Sir Humphry Davy constructed his battery of 2,000 cells, and thus succeeded in exalting the tiny spark obtained in closing the circuit into the luminous sheaf of the voltaic arc. He also observed that the spark passed even when the poles were separated by a distance varying from 1/40 to 1/30 of an inch. This appears to have been subsequently forgotten, as we find later physicists questioning the possibility of the spark leaping over any interpolar distance. Mr. J. P. Gassiot, of Clapham, demonstrated the inaccuracy of this opinion by constructing a battery of 3,000 Leclanche cells, which gave a spark of 0.025 inch; a similar number of “de la Rue” cells gives an 0.0564 inch spark. This considerable increase in potential is chiefly due to better insulation.
The great energy of this battery was illustrated by a variety of experiments. Thus, a large condenser, specially constructed by Messrs. Varley, and having a capacity equal to that of 6,485 large Leyden jars, was almost immediately charged by the current from 10,000 cells. Wires of various kinds, and from 9 inches to 29 inches in length, were instantly volatilized by the passage of the electricity thus stored up. The current induced in the secondary wire of a coil by the discharge of the condenser through the primary, was also sufficiently intense to deflagrate wires of considerable length and thickness.
It was with such power at his command that Dr. De la Rue proceeded to investigate several important electrical laws. He has found, for example, that the positive discharge is more intermittent than the negative, that the arc is always preceded by a streamer-like discharge, that its temperature is about 16,000 deg., and its length at the ordinary pressure of the atmosphere, when taken between two points, varies as the square of the number of cells. Thus, with a battery of 1,000 cells, the arc was 0.0051 inch, with 11,000 cells it increased to 0.62 inch. The same law was found to hold when the discharge took place between a point and a disk; it failed entirely, however, when the terminals were two disks.
It was also shown that the voltaic arc is not a phenomenon of conduction, but is essentially a disruptive discharge, the intervals between the passage of two successive static sparks being the time required for the battery to collect sufficient power to leap over the interposed resistance. This was further confirmed by the introduction of a condenser, when the intervals were perceptibly larger.
Faraday proved that the quantity of electricity necessary to produce a strong flash of lightning would result from the decomposition of a single grain of water, and Dr. de la Rue’s experiments confirm this extraordinary statement. He has calculated that this quantity of electricity would be 5,000 times as great as the charge of his large condenser, and that a lightning flash a mile long would require the potential of 3,500,000 cells, that is to say, of 243 of his powerful batteries.
In experimenting with “vacuum” tubes, he has found that the discharge is also invariably disruptive. This is an important point, as many physicists speak and write of the phenomenon as one of conduction. Air, in every degree of tenuity, refuses to act as a conductor of electricity. These experiments show that the resistance of gaseous media diminishes with the pressure only up to a certain point, beyond which it rapidly increases. Thus, in the case of hydrogen, it diminishes up to 0.642 mm., 845 millionths; it then rises as the exhaustion proceeds, and at 0.00065 mm., 8.6 millionths, it requires as high a potential as at 21.7 mm., 28.553 millionths. At 0.00137 mm., 1.8 millionth, the current from 11,000 cells would not pass through a tube for which 430 cells sufficed at the pressure of minimum resistance. At a pressure of 0.0055 mm., 0.066 millionth, the highest exhaust obtained in any of the experiments, even a one-inch spark from an induction coil refused to pass. It was also ascertained that there is neither condensacian nor dilatation of the gas in contact with the terminals prior to the passage of the discharge.
These researches naturally led to some speculation about the conditions under which auroral phenomena may occur. Observers have variously stated the height at which the aurora borealis attains its greatest brilliancy as ranging between 124 and 281 miles. Dr. de la Rue’s conclusions fix the upper limit at 124 miles, and that of maximum display at 37 miles, admitting also that the aurora may sometimes occur at an altitude of a few thousand feet.
The aurora was beautifully illustrated by a very large tube, in which the theoretical pressure was carefully maintained, the characteristic roseate tinge being readily produced and maintained.
In studying the stratifications observed in vacuum tubes, Dr. de la Rue finds that they originate at the positive pole, and that their steadiness may be regulated by the resistance in circuit, and that even when the least tremor cannot be detected by the eye, they are still produced by rapid pulsations which may be as frequent as ten millions per second.
Dr. de la Rue concluded his interesting discourse by exhibiting some of the finest tubes of his numerous and unsurpassed collection.–_Engineering_
* * * * *
MEASURING ELECTROMOTIVE FORCE.
Coulomb’s torsion balance has been adapted by M. Baille to the measurement of low electromotive forces in a very successful manner, and has been found preferable by him to the delicate electrometers of Sir W. Thomson. It is necessary to guard it from disturbances due to extraneous electric influences and the trembling of the ground. These can be eliminated completely by encircling the instrument in a metal case connected to earth, and mounting it on solid pillars in a still place. Heat also has a disturbing effect, and makes itself felt in the torsion of the fiber and the cage surrounding the lever. These effects are warded off by inclosing the instrument in a non-conducting jacket of wood shavings.
The apparatus of M. Baille consists of an annealed silver torsion wire of 2.70 meters long, and a lever 0.50 meter long, carrying at each extremity a ball of copper, gilded, and three centimeters in diameter. Similar balls are fixed at the corners of a square 20.5 meters in the side, and connected in diagonal pairs by fine wire. The lever placed at equal distances from the fixed balls communicates, by the medium of the torsion wire, with the positive pole of a battery, P, the other pole being to earth.
Owing to some unaccountable variations in the change of the lever or needle, M. Baille was obliged to measure the change at each observation. This was done by joining the + pole of the battery to the needle, and one pair of the fixed balls, and observing the deflection; then the deflection produced by the other balls was observed. This operation was repeated several times.
The battery, X, to be measured consisted of ten similar elements, and one pole of it was connected to the fixed balls, while the other pole was connected to the earth. The needle, of course, remained in contact with the + pole of the charging battery, P.
The deflections were read from a clear glass scale, placed at a distance of 3.30 meters from the needle, and the results worked out from Coulomb’s static formula,
C a = (4 m m’)/d squared, with
______________
/ sum((p/g) r squared)
O = / ————-
\/ C
[TEX: O = \sqrt{\frac{\sum \frac{p}{g} r^2}{C}}]
In M. Baillie’s experiments, O = 437 cubed, and sum(pr squared)= 32171.6 (centimeter grammes), the needle having been constructed of a geometrical form.
The following numbers represent the potential of an element of the battery–that is to say, the quantity of electricity that the pole of that battery spreads upon a sphere of one centimeter radius. They are expressed in units of electricity, the unit being the quantity of electricity which, acting upon a similar unit at a distance of one centimeter, produces a repulsion equal to one gramme:
Volta pile 0.03415 open circuit. Zinc, sulphate of copper, copper 0.02997 ” Zinc, acidulated water, copper, sulphate of copper 0.03709 ” Zinc, salt water, carbon peroxide of manganese 0.05282 ” Zinc, salt water, platinum, chloride of platinum 0.05027 ” Zinc, acidulated water, carbon nitric acid 0.06285 “
These results were obtained just upon charging the batteries, and are, therefore, slightly higher than the potentials given after the batteries became older. The sulphate of copper cells kept about their maximum value longest, but they showed variations of about 10 per cent.
* * * * *
TELEPHONY BY THERMIC CURRENTS.
While in telephonic arrangements, based upon the principle of magnetic induction, a relatively considerable expenditure of force is required in order to set the tightly stretched membrane in vibration, in the so-called carbon telephones only a very feeble impulse is required to produce the differences in the current necessary for the transmission of sounds. In order to produce relatively strong currents, even in case of sound-action of a minimum strength, Franz Kroettlinger, of Vienna, has made an interesting experiment to use thermo electric currents for the transmission of sound to a distance. The apparatus which he has constructed is exceedingly simple. A current of hot air flowing from below upward is deflected more or less from its direction by the human voice. By its action an adjacent thermo-battery is excited, whose current passes through the spiral of an ordinary telephone, which serves as the receiving instrument. As a source of heat the inventor uses a common stearine candle, the flame of which is kept at one and the same level by means of a spring similar to those used in carriage lamps. On one side of the candle is a sheet metal voice funnel fixed upon a support, its mouth being covered with a movable sliding disk, fitted with a suitable number of small apertures. On the other side a similar support holds a funnel-shaped thermo-battery. The single bars of metal forming this battery are very thin, and of such a shape that they may cool as quickly as possible. Both the speaking-funnel and the battery can be made to approach, at will, to the stream of warm air rising up from the flame. The entire apparatus is inclosed in a tin case in such a manner that only the aperture of the voice-funnel and the polar clamps for securing the conducting wires appear on the outside. The inside of the case is suitably stayed to prevent vibration. On speaking into the mouth-piece of the funnel, the sound-waves occasion undulations in the column of hot air which are communicated to the thermo-battery, and in this manner corresponding differences are produced in the currents in the wires leading to the receiving instrument.–_Oesterreichische-Ungarische Post._
* * * * *
THE TELECTROSCOPE.
By MONS. SENLECQ, of Ardres.
This apparatus, which is intended to transmit to a distance through a telegraphic wire pictures taken on the plate of a camera, was invented in the early part of 1877 by M. Senlecq, of Ardres. A description of the first specification submitted by M. Senlecq to M. du Moncel, member of the Paris Academy of Sciences, appeared in all the continental and American scientific journals. Since then the apparatus has everywhere occupied the attention of prominent electricians, who have striven to improve on it. Among these we may mention MM. Ayrton, Perry, Sawyer (of New York), Sargent (of Philadelphia), Brown (of London), Carey (of Boston), Tighe (of Pittsburg), and Graham Bell himself. Some experimenters have used many wires, bound together cable-wise, others one wire only. The result has been, on the one hand, confusion of conductors beyond a certain distance, with the absolute impossibility of obtaining perfect insulation; and, on the other hand, an utter want of synchronism. The unequal and slow sensitiveness of the selenium likewise obstructed the proper working of the apparatus. Now, without a relative simplicity in the arrangement of the conducting wires intended to convey to a distance the electric current with its variations of intensity, without a perfect and rapid synchronism acting concurrently with the luminous impressions, so as to insure the simultaneous action of transmitter and receiver, without, in fine, an increased sensitiveness in the selenium, the idea of the telectroscope could not be realized. M. Senlecq has fortunately surmounted most of these main obstacles, and we give to-day a description of the latest apparatus he has contrived.
TRANSMITTER.
A brass plate, A, whereon the rays of light impinge inside a camera, in their various forms and colors, from the external objects placed before the lens, the said plate being coated with selenium on the side intended to face the dark portion of the camera This brass plate has its entire surface perforated with small holes as near to one another as practicable. These holes are filled with selenium, heated, and then cooled very slowly, so as to obtain the maximum sensitiveness. A small brass wire passes through the selenium in each hole, without, however, touching the plate, on to the rectangular and vertical ebonite plate, B, Fig. 1, from under this plate at point, C. Thus, every wire passing through plate, A, has its point of contact above the plate, B, lengthwise. With this view the wires are clustered together when leaving the camera, and thence stretch to their corresponding points of contact on plate, B, along line, C C. The surface of brass, A, is in permanent contact with the positive pole of the battery (selenium). On each side of plate, B, are let in two brass rails, D and E, whereon the slide hereinafter described works.
[Illustration: Fig. 1]
Rail, E, communicates with the line wire intended to conduct the various light and shade vibrations. Rail, D, is connected with the battery wire. Along F are a number of points of contact corresponding with those along C C. These contacts help to work the apparatus, and to insure the perfect isochronism of the transmitter and receiver. These points of contact, though insulated one from the other on the surface of the plate, are all connected underneath with a wire coming from the positive pole of a special battery. This apparatus requires two batteries, as, in fact, do all autographic telegraphs–one for sending the current through the selenium, and one for working the receiver, etc. The different features of this important plate may, therefore, be summed up thus:
FIGURE 1.
D. Brass rail, grooved and connected with the line wire working the receiver.
F. Contacts connected underneath with a wire permanently connected with battery.
C. Contacts connected to insulated wires from selenium.
E. Brass rail, grooved, etc., like D.
RECEIVER.
A small slide, Fig. 2, having at one of its angles a very narrow piece of brass, separated in the middle by an insulating surface, used for setting the apparatus in rapid motion. This small slide has at the points, D D, a small groove fitting into the brass rails of plate, B, Fig. 1, whereby it can keep parallel on the two brass rails, D and E. Its insulator, B, Fig. 2, corresponds to the insulating interval between F and C, Fig. 1.
A, Fig. 3, circular disk, suspended vertically (made of ebonite or other insulating material). This disk is fixed. All round the inside of its circumference are contacts, connected underneath with the corresponding wires of the receiving apparatus. The wires coming from the seleniumized plate correspond symmetrically, one after the other, with the contacts of transmitter. They are connected in the like order with those of disk, A, and with those of receiver, so that the wire bearing the No. 5 from the selenium will correspond identically with like contact No. 5 of receiver.
D, Fig. 4, gutta percha or vulcanite insulating plate, through which pass numerous very fine platinum wires, each corresponding at its point of contact with those on the circular disk, A.
The receptive plate must be smaller than the plate whereon the light impinges. The design being thus reduced will be the more perfect from the dots formed by the passing currents being closer together.
B, zinc or iron or brass plate connected to earth. It comes in contact with chemically prepared paper, C, where the impression is to take place. It contributes to the impression by its contact with the chemically prepared paper.
In E, Fig. 3, at the center of the above described fixed plate is a metallic axis with small handle. On this axis revolves brass wheel, F, Fig. 5.
[Illustration: FIG. 2]
On handle, E, presses continuously the spring, H, Fig. 3, bringing the current coming from the selenium line. The cogged wheel in Fig. 5 has at a certain point of its circumference the sliding spring, O, Fig. 5, intended to slide as the wheel revolves over the different contacts of disk, A, Fig. 3.
This cogged wheel, Fig. 5, is turned, as in the dial telegraphs, by a rod working in and out under the successive movements of the electro-magnet, H, and of the counter spring. By means of this rod (which must be of a non-metallic material, so as not to divert the motive current), and of an elbow lever, this alternating movement is transmitted to a catch, G, which works up and down between the cogs, and answers the same purpose as the ordinary clock anchor.
[Illustration: FIG. 3]
This cogged wheel is worked by clockwork inclosed between two disks, and would rotate continuously were it not for the catch, G, working in and out of the cogs. Through this catch, G, the wheel is dependent on the movement of electro-magnet. This cogged wheel is a double one, consisting of two wheels coupled together, exactly similar one with the other, and so fixed that the cogs of the one correspond with the void between the cogs of the others. As the catch, G, moves down it frees a cog in first wheel, and both wheels begin to turn, but the second wheel is immediately checked by catch, G, and the movement ceases. A catch again works the two wheels, turn half a cog, and so on. Each wheel contains as many cogs as there are contacts on transmitter disk, consequently as many as on circular disk, A, Fig. 3, and on brass disk within camera.
[Illustration: FIG. 4]
[Illustration: FIG. 5]
Having now described the several parts of the apparatus, let us see how it works. All the contacts correspond one with the other, both on the side of selenium current and that of the motive current. Let us suppose that the slide of transmitter is on contact No. 10 for instance; the selenium current starting from No. 10 reaches contact 10 of rectangular transmitter, half the slide bearing on this point, as also on the parallel rail, communicates the current to said rail, thence to line, from the line to axis of cogged wheel, from axis to contact 10 of circular fixed disk, and thence to contact 10 of receiver. At each selenium contact of the rectangular disk there is a corresponding contact to the battery and electro-magnet. Now, on reaching contact 10 the intermission of the current has turned the wheel 10 cogs, and so brought the small contact, O, Fig. 5, on No. 10 of the fixed circular disk.
As may be seen, the synchronism of the apparatus could not be obtained in a more simple and complete mode–the rectangular transmitter being placed vertically, and the slide being of a certain weight to its fall from the first point of contact sufficient to carry it rapidly over the whole length of this transmitter.
The picture is, therefore, reproduced almost instantaneously; indeed, by using platinum wires on the receiver connected with the negative pole, by the incandescence of these wires according to the different degrees of electricity we can obtain a picture, of a fugitive kind, it is true, but yet so vivid that the impression on the retina does not fade during the relatively very brief space of time the slide occupies in traveling over all the contacts. A Ruhmkorff coil may also be employed for obtaining sparks in proportion to the current emitted. The apparatus is regulated in precisely the same way as dial telegraphs, starting always from first contact. The slide should, therefore, never be removed from the rectangular disk, whereon it is held by the grooves in the brass rails, into which it fits with but slight friction, without communicating any current to the line wires when not placed on points of contact.
* * * * *
[Continued from SUPPLEMENT No. 274, page 4368.]
THE VARIOUS MODES OF TRANSMITTING POWER TO A DISTANCE.
[Footnote: A paper lately read before the Institution of Mechanical Engineers.]
By ARTHUR ACHARD, of Geneva.
But allowing that the figure of 22 H. P., assumed for this power (the result in calculating the work with compressed air being 19 H. P.) may be somewhat incorrect, it is unlikely that this error can be so large that its correction could reduce the efficiency below 80 per cent. Messrs. Sautter and Lemonnier, who construct a number of compressors, on being consulted by the author, have written to say that they always confined themselves in estimating the power stored in the compressed air, and had never measured the gross power expended. Compressed air in passing along the pipe, assumed to be horizontal, which conveys it from the place of production to the place where it is to be used, experiences by friction a diminution of pressure, which represents a reduction in the mechanical power stored up, and consequently a loss of efficiency.
The loss of pressure in question can only be calculated conveniently on the hypothesis that it is very small, and the general formula,
p1 – p 4L
——- = —- f(u),
[Delta] D
[TEX: \frac{p_1 – p}{\Delta} = \frac{4L}{D}f(u)]
is employed for the purpose, where D is the diameter of the pipe, assumed to be uniform, L the length of the pipe, p1 the pressure at the entrance, p the pressure at the farther end, u the velocity at which the compressed air travels, [Delta] its specific weight, and f(u) the friction per unit of length. In proportion as the air loses pressure its speed increases, while its specific weight diminishes; but the variations in pressure are assumed to be so small that u and [Delta] may be considered constant. As regards the quantity f(u), or the friction per unit of length, the natural law which regulates it is not known, audit can only be expressed by some empirical formula, which, while according sufficiently nearly with the facts, is suited for calculation. For this purpose the binomial formula, au + bu squared, or the simple formula, b1 u squared, is generally adopted; a b and b1 being coefficients deduced from experiment. The values, however, which are to be given to these coefficients are not constant, for they vary with the diameter of the pipe, and in particular, contrary to formerly received ideas, they vary according to its internal surface. The uncertainty in this respect is so great that it is not worth while, with a view to accuracy, to relinquish the great convenience which the simple formula, b1 u squared, offers. It would be better from this point of view to endeavor, as has been suggested, to render this formula more exact by the substitution of a fractional power in the place of the square, rather than to go through the long calculations necessitated by the use of the binomial au + bu squared. Accordingly, making use of the formula b1 u squared, the above equation becomes,
p1 – p 4L
——- = —- b1 u squared;
[Delta] D
[TEX: \frac{p_1 – p}{\Delta} = \frac{4L}{D} b_1 u^2]
or, introducing the discharge per second, Q, which is the usual figure supplied, and which is connected with the velocity by the relation, Q = ([pi] D squared u)/4, we have
p1 – p 64 b1
——- = ——— L Q squared.
[Delta] [pi] squared D^5
[TEX: \frac{p_1 – p}{\Delta} = \frac{64 b_1}{\pi^2 D^5} L Q^2]
Generally the pressure, p1, at the entrance is known, and the pressure, p, has to be found; it is then from p1 that the values of Q and [Delta] are calculated. In experiments where p1 and p are measured directly, in order to arrive at the value of the coefficient b1, Q and [Delta] would be calculated for the mean pressure 1/2(p1 + p). The values given to the coefficient b1 vary considerably, because, as stated above, it varies with the diameter, and also with the nature of the material of the pipe. It is generally admitted that it is independent of the pressure, and it is probable that within certain limits of pressure this hypothesis is in accordance with the truth.
D’Aubuisson gives for this case, in his _Traite d’Hydraulique_, a rather complicated formula, containing a constant deduced from experiment, whose value, according to a calculation made by the author, is approximately b1 = 0.0003. This constant was determined by taking the mean of experiments made with tin tubes of 0.0235 meter (15/16 in.), 0.05 meter (2 in.), and 0.10 meter (4 in.) diameter; and it was erroneously assumed that it was correct for all diameters and all substances.
M. Arson, engineer to the Paris Gas Company, published in 1867, in the _Memoires de la Societe des Ingenieurs Civils de France_, the results of some experiments on the loss of pressure in gas when passing through pipes. He employed cast-iron pipes of the ordinary type. He has represented the results of his experiments by the binomial formula, au + bu squared, and gives values for the coefficients a and b, which diminish with an increase in diameter, but would indicate greater losses of pressure than D’Aubuisson’s formula. M. Deviller, in his _Rapport sur les travaux de percement du tunnel sous les Alpes_, states that the losses of pressure observed in the air pipe at the Mont Cenis Tunnel confirm the correctness of D’Aubuisson’s formula; but his reasoning applies to too complicated a formula to be absolutely convincing.
Quite recently M. E. Stockalper, engineer-in-chief at the northern end of the St. Gothard Tunnel, has made some experiments on the air conduit of this tunnel, the results of which he has kindly furnished to the author. These lead to values for the coefficient b1 appreciably less than that which is contained implicitly in D’Aubuisson’s formula. As he experimented on a rising pipe, it is necessary to introduce into the formula the difference of level, h, between the two ends; it then becomes
p1 – p 64 b1
——- = ——— L Q squared + h. [Delta] [pi] squared D^5
[TEX: \frac{p_1 – p}{\Delta} = \frac{64 b_1}{\pi^2 D^5} L Q^2 + h]
The following are the details of the experiments: First series of experiments: Conduit consisting of cast or wrought iron pipes, joined by means of flanges, bolts, and gutta percha rings. D = 0.20 m. (8 in.); L = 4,600 m. (15,100 ft,); h= 26.77 m. (87 ft. 10 in.). 1st experiment: Q = 0.1860 cubic meter (6.57 cubic feet), at a pressure of 1/2(p1 + p), and a temperature of 22 deg. Cent. (72 deg. Fahr.); p1 = 5.60 atm., p =5.24 atm. Hence p1 – p = 0.36 atm.= 0.36 x 10,334 kilogrammes per square meter (2.116 lb. per square foot), whence we obtain b1=0.0001697. D’Aubuisson’s formula would have given p1 – p = 0.626 atm.; and M. Arson’s would have given p1 – p = 0.9316 atm. 2d experiment: Q = 0.1566 cubic meter (5.53 cubic feet), at a pressure of 1/2(p1 + p), and a temperature of 22 deg. Cent. (72 deg. Fahr.); p1 = 4.35 atm., p = 4.13 atm. Hence p1 – p = 0.22 atm. = 0.22 X 10,334 kilogrammes per square meter (2,116 lb. per square foot); whence we obtain b1 = 0.0001816. D’Aubuisson’s formula would have given p1 – p = 0.347 atm; and M. Arson’s would have given p1 – p = 0.5382 atm. 3d experiment: Q = 0.1495 cubic meter (5.28 cubic feet) at a pressure of 1/2(p1 + p) and a temperature 22 deg. Cent. (72 Fahr.); p1 = 3.84 atm., p = 3.65 atm. Hence p1 – p = 0.19 atm. = 0.19 X 10,334 kilogrammes per square meter (2.116 lb. per square foot); whence we obtain B1 = 0.0001966. D’Aubuisson’s formula would have given p1 – p = 0.284 atm., and M. Arson’s would have given p1 – p = 0.4329 atm. Second series of experiments: Conduit composed of wrought-iron pipes, with joints as in the first experiments. D = 0.15 meter (6 in.), L – 0.522 meters (1,712 ft.), h = 3.04 meters (10 ft.) 1st experiments: Q = 0.2005 cubic meter (7.08 cubic feet), at a pressure of 1/2(p1 + p), and a temperature of 26.5 deg. Cent. (80 deg. Fahr.); p1 = 5.24 atm., p = 5.00 atm. Hence p1 – p = 0.24 atm. =0.24 x 10,334 kilogrammes per square meter (2,116 lb. per square foot); whence we obtain b1 = 0.3002275. 2nd experiment: Q = 0.1586 cubic meter (5.6 cubic feet), at a pressure of 1/2(p1 + p), and a temperature of 26.5 deg. Cent. (80 deg. Fahr.); p1 = 3.650 atm., p = 3.545 atm. Hence p1 – p = 0.105 atm. = 0.105 x 10,334 kilogrammes per square meter (2,116 lb. per square foot); whence we obtain b1 = 0.0002255. It is clear that these experiments give very small values for the coefficient. The divergence from the results which D’Aubuisson’s formula would give is due to the fact that his formula was determined with very small pipes. It is probable that the coefficients corresponding to diameters of 0.15 meter (6 in.) and 0.20 meter (8 in.) for a substance as smooth as tin, would be still smaller respectively than the figures obtained above.
The divergence from the results obtained by M. Arson’s formula does not arise from a difference in size, as this is taken into account. The author considers that it may be attributed to the fact that the pipes for the St. Gothard Tunnel were cast with much greater care than ordinary pipes, which rendered their surface smoother, and also to the fact that flanged joints produce much less irregularity in the internal surface than the ordinary spigot and faucet joints.
Lastly, the difference in the methods of observation and the errors which belong to them, must be taken into account. M. Stockalper, who experimented on great pressures, used metallic gauges, which are instruments on whose sensibility and correctness complete reliance cannot be placed; and moreover the standard manometer with which they were compared was one of the same kind. The author is not of opinion that the divergence is owing to the fact that M. Stockalper made his observations on an air conduit, where the pressure was much higher than in gas pipes. Indeed, it may be assumed that gases and liquids act in the same manner; and, as will be [1] explained later on, there is reason to believe that with the latter a rise of pressure increases the losses of pressure instead of diminishing them.
[Transcribers note 1: corrected from ‘as will we explained’]
All the pipes for supplying compressed air in tunnels and in headings of mines are left uncovered, and have flanged joints; which are advantages not merely as regards prevention of leakage, but also for facility of laying and of inspection. If a compressed air pipe had to be buried in the ground the flanged joint would lose a part of its advantages; but, nevertheless, the author considers that it would still be preferable to the ordinary joint.
It only remains to refer to the motors fed with the compressed air. This subject is still in its infancy from a practical point of view. In proportion as the air becomes hot by compression, so it cools by expansion, if the vessel containing it is impermeable to heat. Under these conditions it gives out in expanding a power appreciably less than if it retained its original temperature; besides which the fall of temperature may impede the working of the machine by freezing the vapor of water contained in the air.
If it is desired to utilize to the utmost the force stored up in the compressed air it is necessary to endeavor to supply heat to the air during expansion so as to keep its temperature constant. It would be possible to attain this object by the same means which prevent heating from compression, namely, by the circulation and injection of water. It would perhaps be necessary to employ a little larger quantity of water for injection, as the water, instead of acting by virtue both of its heat of vaporization and of its specific heat, can in this case act only by virtue of the latter. These methods might be employed without difficulty for air machines of some size. It would be more difficult to apply them to small household machines, in which simplicity is an essential element; and we must rest satisfied with imperfect methods, such as proximity to a stove, or the immersion of the cylinder in a tank of water. Consequently loss of power by cooling and by incomplete expansion cannot be avoided. The only way to diminish the relative amount of this loss is to employ compressed air at a pressure not exceeding three or four atmospheres.
The only real practical advance made in this matter is M. Mekarski’s compressed air engine for tramways. In this engine the air is made to pass through a small boiler containing water at a temperature of about 120 deg. Cent. (248 deg. Fahr.), before entering the cylinder of the engine. It must be observed that in order to reduce the size of the reservoirs, which are carried on the locomotive, the air inside them must be very highly compressed; and that in going from the reservoir into the cylinder it passes through a reducing valve or expander, which keeps the pressure of admission at a definite figure, so that the locomotive can continue working so long as the supply of air contained in the reservoir has not come down to this limiting pressure. The air does not pass the expander until after it has gone through the boiler already mentioned. Therefore, if the temperature which it assumes in the boiler is 100 deg. Cent. (212 deg. Fahr.), and if the limiting pressure is 5 atm., the gas which enters the engine will be a mixture of air and water vapor at 100 deg. Cent.; and of its total pressure the vapor of water will contribute I atm. and the air 4 atm. Thus this contrivance, by a small expenditure of fuel, enables the air to act expansively without injurious cooling, and even reduces the consumption of compressed air to an extent which compensates for part of the loss of power arising from the preliminary expansion which the air experiences before its admission into the engine. It is clear that this same contrivance, or what amounts to the same thing, a direct injection of steam, at a sufficient pressure, for the purpose of maintaining the expanding air at a constant temperature, might be tried in a fixed engine worked by compressed air with some chance of success.
Whatever method is adopted it would be advantageous that the losses of pressure in the pipes connecting the compressors with the motors should be reduced as much as possible, for in this case that loss would represent a loss of efficiency. If, on the other hand, owing to defective means of reheating, it is necessary to remain satisfied with a small amount of expansion, the loss of pressure in the pipe is unimportant, and has only the effect of transferring the limited expansion to a point a little lower on the scale of pressures. If W is the net disposable force on the shaft of the engine which works the compressor, v1 the volume of air at the compressor, p1. given by the compressor, and at the temperature of the surrounding air, and p0 the atmospheric pressure, the efficiency of the compressor, assuming the air to expand according to Boyle’s law, is given by the well-known formula–
p1 v1 log (p1 / p0)
——————-.
W
[TEX: \frac{p_1 v_1 \log \frac{p_1}{p_0}}{W}]
Let p2 be the value to which the pressure is reduced by the loss of pressure at the end of the conduit, and v2 the volume which the air occupies at this pressure and at the same temperature; the force stored up in the air at the end of its course through the conduit is p2 v2 log(p2/p0); consequently, the efficiency of the conduit is
p2 v2 log(p2/p0)
—————-
p1 v1 log(p1/p0)
[TEX: \frac{p_2 v_2 \log\frac{p_2}{p_0}}{p_2 v_2 \log\frac{p_2}{p_0}}]
a fraction that may be reduced to the simple form
log(p2/p0)
———-,
log(p1/p0)
[TEX: \frac{\log\frac{p_2}{p_0}}{\log\frac{p_2}{p_0}}]
if there is no leakage during the passage of the air, because in that cause p2 v2 = p1 v1. Lastly, if W1 is the net disposable force on the shaft of the compressed air motor, the efficiency of this engine will be,
W1
—————-
p2 v2 log(p2/p0)
[TEX: \frac{W_1}{p_2 v_2 \log \frac{p_2}{p_0}}]
and the product of these three partial efficiencies is equal to W1/W, the general efficiency of the transmission.
III. _Transmission by Pressure Water_.–As transmission of power by compressed air has been specially applied to the driving of tunnels, so transmission by pressure water has been specially resorted to for lifting heavy loads, or for work of a similar nature, such as the operations connected with the manufacture of Bessemer steel or of cast-iron pipes. The author does not propose to treat of transmissions established for this special purpose, and depending on the use of accumulators at high pressure, as he has no fresh matter to impart on this subject, and as he believes that the remarkable invention of Sir William Armstrong was described for the first time, in the “Proceedings of the Institution of Mechanical Engineers.” His object is to refer to transmissions applicable to general purposes.
The transmission of power by water may occur in another form. The motive force to be transmitted may be employed for working pumps which raise the water, not to a fictitious height in an accumulator, but to a real height in a reservoir, with a channel from this reservoir to distribute the water so raised among several motors arranged for utilizing the pressure. The author is not aware that works have been carried out for this purpose. However, in many towns a part of the water from the public mains serves to supply small motors–consequently, if the water, instead of being brought by a natural fall, has been previously lifted artificially, it might be said that a transmission of power is here grafted on to the ordinary distribution of water.
Unless a positive or negative force of gravity is introduced into the problem, independently of the force to be transmitted, the receivers of the water pressure must be assumed to be at the same level as the forcing pumps, or more correctly, the water discharged from the receivers to be at the same level as the surface of the water from which the pumps draw their supply. In this case the general efficiency of transmission is the product of three partial efficiencies, which correspond exactly to those mentioned with regard to compressed air. The height of lift, contained in the numerator of the fraction which expresses the efficiency of the pumps, is not to be taken as the difference in level between the surface of the water in the reservoir and the surface of the water whence the pumps draw their supply; but as this difference in level, plus the loss of pressure in the suction pipe, which is usually very short, and plus the loss in the channel to the reservoir, which may be very long. A similar loss of initial pressure affects the efficiency of the discharge channel. The reservoir, if of sufficient capacity, may become an important store of power, while the compressed air reservoir can only do so to a very limited extent.
Omitting the subject of the pumps, and passing on at once to the discharge main, the author may first point out that the distinction between the ascending and descending mains of the system is of no importance, for two reasons: first, that nothing prevents the motors being supplied direct from the first alone; and second, that the one is not always distinct from the other. In fact, the reservoir may be connected by a single branch pipe with the system which goes from the pumps to the motors; it may even be placed at the extreme end of this system beyond the motors, provided always that the supply pipe is taken into it at the bottom. The same formula may be adopted for the loss of initial pressure in water pipes as for compressed air pipes, viz.,
p1 – p 64 b1
——- = ——— L Q squared +- h; [Delta] [pi] squared D^5
[TEX: \frac{p_1 – p}{\Delta} = \frac{64 b_1}{\pi^2 D^5} L Q^2 \pm h]
h being the difference of level between the two ends of the portion of conduit of length, L, and the sign + or – being used according as the conduit rises or falls. The specific weight, [delta], is constant, and the quotients, p1/[delta] and p/[delta], represent the heights, z and z1, to which the water could rise above the pipes, in vertical tubes branching from it, at the beginning and end of the transit. The values assigned to the coefficient b1 in France, are those determined by D’Arcy. For new cast-iron pipes he gives b1 – 0.0002535 + 1/D 0.000000647; and recommends that this value should be doubled, to allow for the rust and incrustation which more or less form inside the pipes during use. The determination of this coefficient has been made from experiments where the pressure has not exceeded four atmospheres; within these limits the value of the coefficient, as is generally admitted, is independent of the pressure. The experiments made by M. Barret, on the pressure pipes of the accumulator at the Marseilles docks, seem to indicate that the loss of pressure would be greater for high pressures, everything else being equal. This pipe, having a diameter of 0.127 m. (5 in.), was subjected to an initial pressure of 52 atmospheres. The author gives below the results obtained for a straight length 320 m. (1050 ft) long; and has placed beside them the results which D’Arcy’s formula would give.
Loss of head, in meters or ft. respectively per 100 meters or ft. run of pipes. +—————–^——————-+ | |
Calculated loss. +———–^———–+ | |
Velocity of flow Actual loss
per second. observed. Old pipes. New pipes. Meters. Feet. Met. or Ft. Met. or Ft. Met. or Ft. 0.25 0.82 1.5 0.12 0.06
0.50 1.64 2.5 0.48 0.24 0.75 2.46 3.7 1.08 0.54
1.00 3.28 5.5 1.92 0.96 1.25 4.10 6.1 3.00 1.50
1.50 4.92 7.3 4.32 2.16 1.75 5.74 8.0 5.88 2.94
2.00 6.56 10.2 7.68 3.84 2.25 7.38 11.7 9.72 4.86
2.50 8.20 14.0 12.00 6.00
Moreover, these results would appear to indicate a different law from that which is expressed by the formula b1 u squared, as is easy to see by representing them graphically. It would be very desirable that fresh experiments should be made on water pipes at high pressure, and of various diameters. Of machines worked by water pressure the author proposes to refer only to two which appear to him in every respect the most practical and advantageous. One is the piston machine of M. Albert Schmid, engineer at Zurich. The cylinder is oscillating, and the distribution is effected, without an eccentric, by the relative motion of two spherical surfaces fitted one against the other, and having the axis of oscillation for a common axis. The convex surface, which is movable and forms part of the cylinder, serves as a port face, and has two ports in it communicating with the two ends of the cylinder. The concave surface, which is fixed and plays the part of a slide valve, contains three openings, the two outer ones serving to admit the pressure water, and the middle one to discharge the water after it has exerted its pressure. The piston has no packing. Its surface of contact has two circumferential grooves, which produce a sort of water packing acting by adhesion. A small air chamber is connected with the inlet pipe, and serves to deaden the shocks. This engine is often made with two cylinders, having their cranks at right angles.
The other engine, which is much less used, is a turbine on Girard’s system, with a horizontal axis and partial admission, exactly resembling in miniature those which work in the hydraulic factory of St. Maur, near Paris. The water is introduced by means of a distributer, which is fitted in the interior of the turbine chamber, and occupies a certain portion of its circumference. This turbine has a lower efficiency than Schmid’s machine, and is less suitable for high pressures; but it possesses this advantage over it, that by regulating the amount of opening of the distributer, and consequently the quantity of water admitted, the force can be altered without altering the velocity of rotation. As it admits of great speeds, it could be usefully employed direct, without the interposition of spur wheels or belts for driving magneto-electric machines employed for the production of light, for electrotyping, etc.
In compressed air machines the losses of pressure due to incomplete expansion, cooling, and waste spaces, play an important part. In water pressure machines loss does not occur from these causes, on account of the incompressibility of the liquid, but the frictions of the parts are the principal causes of loss of power. It would be advisable to ascertain whether, as regards this point, high or low pressures are the most advantageous. Theoretical considerations would lead the author to imagine that for a piston machine low pressures are preferable. In conclusion, the following table gives the efficiencies of a Girard turbine, constructed by Messrs. Escher Wyss & Co., of Zurich, and of a Schmid machine, as measured by Professor Fliegnor, in 1871:
ESCHER WYSS & CO’S TURBINE.
Effective Head of Water. Revolutions Efficiency. per minute.
Meters. Feet. Revs. Per cent. 20.7 67.9 628 68.5
20.7 67.9 847 47.4
24.1 79.0 645 68.5
27.6 90.5 612 65.7
27.6 90.5 756 68.0
31.0 101.7 935 56.9
31.0 101.7 1,130 35.1
SCHMID MOTOR.
8.3 27.2 226 37.4
11.4 37.4 182 67.4
14.5 47.6 254 53.4
17.9 58.7 157 86.2
20.7 67.9 166 89.6
20.7 67.9 225 74.6
24.1 79.0 238 76.7
24.1 79.0 389 64.0
27.6 90.5 207 83.9
It will be observed that these experiments relate to low pressures; it would be desirable to extend them to higher pressures.
IV. _Transmission by Electricity._–However high the efficiency of an electric motor may be, in relation to the chemical work of the electric battery which feeds it, force generated by an electric battery is too expensive, on account of the nature of the materials consumed, for a machine of this kind ever to be employed for industrial purposes. If, however, the electric current, instead of being developed by chemical work in a battery, is produced by ordinary mechanical power in a magneto-electric or dynamo-electric machine, the case is different; and the double transformation, first of the mechanical force into an electric current, and then of that current into mechanical force, furnishes a means for effecting the conveyance of the power to a distance.
It is this last method of transmission which remains to be discussed. The author, however, feels himself obliged to restrict himself in this matter to a mere summary; and, indeed, it is English physicists and engineers who have taken the technology of electricity out of the region of empiricism and have placed it on a scientific and rational basis. Moreover, they are also taking the lead in the progress which is being accomplished in this branch of knowledge, and are best qualified to determine its true bearings. When an electric current, with an intensity, i, is produced, either by chemical or mechanical work, in a circuit having a total resistance, R, a quantity of heat is developed in the circuit, and this heat is the exact equivalent of the force expended, so long as the current is not made use of for doing any external work. The expression for this quantity of heat, per unit of time, is Ai squaredR; A being the thermal equivalent of the unit of power corresponding to the units of current and resistance, in which i and R are respectively expressed. The product, i squaredR, is a certain quantity of power, which the author proposes to call _power transformed into electricity_. When mechanical power is employed for producing a current by means of a magneto-electric or dynamo-electric machine–or, to use a better expression, by means of a _mechanical generator of electricity_–it is necessary in reality to expend a greater quantity of power than i squaredR in order to make up for losses which result either from ordinary friction or from certain electro magnetic reactions which occur. The ratio of the quantity, i squaredR, to the power, W, actually expended per unit of time is called the efficiency of the generator. Designating it by K, we obtain, W = i squaredR/K. It is very important to ascertain the value of this efficiency, considering that it necessarily enters as a factor into the evaluation of all the effects to be produced by help of the generator in question. The following table gives the results of certain experiments made early in 1879, with a Gramme machine, by an able physicist, M Hagenbach, Professor at the University at Basle, and kindly furnished by him to the author:
Revolutions per minute 935 919.5 900.5 893
Total resistance in Siemens’ units 2.55 3.82 4.94 6.06
Total resistance in absolute units 2.435 3.648 4.718 5.787 x10^9 x10^9 x10^9 x10^9
Intensity in chemical units 17.67 10.99 8.09 6.28
Intensity in absolute units 2.828 1.759 1.295 1.005
Work done i squaredR in absolute units 1948.6 1129.2 791.3 584.9 x10^7 x10^7 x10^7 x10^7
Work done i squaredR in kilogrammes 198.6 115.1 80.66 59.62
Power expended in kilogrammes 301.5 141.0 86.25 83.25
Efficiency, per cent. 65.9 81.6 93.5 71.6
M. Hagenbach’s dynamometric measurements were made by the aid of a brake. After each experiment on the electric machine, he applied the brake to the engine which he employed, taking care to make it run at precisely the same speed, with the same pressure of steam, and with the same expansion as during experiment. It would certainly be better to measure the force expended during and not after the experiment, by means of a registering dynamometer. Moreover, M. Hagenbach writes that his measurements by means of the brake were very much prejudiced by external circumstances; doubtless this is the reason of the divergences between the results obtained.
About the same time Dr. Hopkinson communicated to this institution the results of some very careful experiments made on a Siemens machine. He measured the force expended by means of a registering dynamometer, and obtained very high coefficients of efficiency, amounting to nearly 90 per cent. M. Hagenbach also obtained from one machine a result only a little less than unity. Mechanical generators of electricity are certainly capable of being improved in several respects, especially as regards their adaptation to certain definite classes of work. But there appears to remain hardly any margin for further progress as regards efficiency. Force transformed into electricity in a generator may be expressed by i [omega] M C; [omega] being the angular velocity of rotation; M the magnetism of one of the poles, inducing or induced, which intervenes; and C a constant specially belonging to each apparatus, and which is independent of the units adopted. This constant could not be determined except by an integration practically impossible; and the product, M C, must be considered indivisible. Even in a magneto-electric machine (with permanent inducing magnets), and much more in a dynamo-electric machine (inducing by means of electro-magnets excited by the very current produced) the product, M C, is a function of the intensity. From the identity of the expressions, i squaredR and i [omega] M C we obtain the relation M C = IR/[omega] which indicates the course to be pursued to determine experimentally the law which connects the variations of M C with those of i. Some experiments made in 1876, by M. Hagenbach, on a Gramme dynamo-electric machine, appear to indicate that the magnetism, M C, does not increase indefinitely with the intensity, but that there is some maximum value for this quantity. If, instead of working a generator by an external motive force, a current is passed through its circuit in a certain given direction, the movable part of the machine will begin to turn in an opposite direction to that in which it would have been necessary to turn it in order to obtain a current in the aforesaid direction. In virtue of this motion the electro-magnetic forces which are generated may be used to overcome a resisting force. The machine will then work as a motor or receiver. Let i be the intensity of the external current which works the motor, when the motor is kept at rest. If it is now allowed to move, its motion produces, in virtue of the laws of induction, a current in the circuit of intensity, i1, in the opposite direction to the external current; the effective intensity of the current traversing the circuit is thus reduced to i – i1. The intensity of the counter current is given, like that of the generating current, by the equation, i1 squaredR = i1 [omega]1 M1 C1, or i1R = [omega]1 M1 C1, the index, 1, denoting the quantities relating to the motor. Here M1 C1 is a function of i – i1, not of i. As in a generator the force transformed into electricity has a value, i [omega] M C, so in a motor the force developed by electricity is (i – i1) [omega]1 M1 C1. On account, however, of the losses which occur, the effective power, that is the disposable power on the shaft of the motor, will have a smaller value, and in order to arrive at it a coefficient of efficiency, K1, must be added. We shall then have W1 = K1 (i-i1) [omega]1 M1 C1. The author has no knowledge of any experiments having been made for obtaining this efficiency, K1. Next let us suppose that the current feeding the motor is furnished by a generator, so that actual transmission by electricity is taking place. The circuit, whose resistance is R, comprises the coils, both fixed and movable, of the generator and motor, and of the conductors which connect them. The intensity of the current which traverses the circuit had the value, i, when the motor was at rest; by the working of the motor it is reduced to i – i1. The power applied to the generator is itself reduced to W-[(i-i1)[omega] M C]/K. The prime mover is relieved by the action of the counter current, precisely as the consumption of zinc in the battery would be reduced by the same cause, if the battery was the source of the current. The efficiency of the transmission is W1/W. Calculation shows that it is expressed by the following equations:W1/W = K K1 [([omega]11 M1 C1)/([omega]1 M C)], or = K K1 [([omega]11 M1 C)/([omega]11 M1 C1 + (i-i1) R)]; expressions in which it must be remembered M C and M1 C1 are really functions of (i-i1). This efficiency is, then, the product of three distinct factors, each evidently less than unity, namely, the efficiency belonging to the generator, the efficiency belonging to the motor, and a third factor depending on the rate of rotation of the motor and the resistance of the circuit. The influence which these elements exert on the value of the third factor cannot be estimated, unless the law is first known according to which the magnetisms, M C, M1 C C1, vary with the intensity of the current.
GENERAL RESULTS.
Casting a retrospective glance at the four methods of transmission of power which have been examined, it would appear that transmission by ropes forms a class by itself, while the three other methods combine into a natural group, because they possess a character in common of the greatest importance. It may be said that all three involve a temporary transformation of the mechanical power to be utilized into potential energy. Also in each of these methods the efficiency of transmission is the product of three factors or partial efficiencies, which correspond exactly–namely, first, the efficiency of the instrument which converts the actual energy of the prime mover into potential energy; second, the efficiency of the instrument which reconverts this potential energy into actual energy, that is, into motion, and delivers it up in this shape for the actual operations which accomplish industrial work; third, the efficiency of the intermediate agency which serves for the conveyance of potential energy from the first instrument to the second.
This last factor has just been given for transmission by electricity. It is the exact correlative of the efficiency of the pipe in the case of compressed air or of pressure water. It is as useful in the case of electric transmission, as of any other method, to be able, in studying the system, to estimate beforehand what results it is able to furnish, and for this purpose it is necessary to calculate exactly the factors which compose the efficiency.
In order to obtain this desirable knowledge, the author considers that the three following points should form the aim of experimentalists: First, the determination of the efficiency, K, of the principal kinds of magneto-electric, or dynamo-electric machines working as generators; second, the determination of the efficiency, K1, of the same machines working as motors; third, the determination of the law according to which the magnetism of the cores of these machines varies with the intensity of the current. The author is of opinion that experiments made with these objects in view would be more useful than those conducted for determining the general efficiency of transmission, for the latter give results only available under precisely similar conditions. However, it is clear that they have their value and must not be neglected.
There are, moreover, many other questions requiring to be elucidated by experiment, especially as regards the arrangement of the conducting wires: but it is needless to dwell further upon this subject, which has been ably treated by many English men of science–for instance, Dr. Siemens and Professor Ayrton. Nevertheless, for further information the author would refer to the able articles published at Paris, by M. Mascart, in the _Journal de Physique_, in 1877 and 1878. The author would gladly have concluded this paper with a comparison of the efficiencies of the four systems which have been examined, or what amounts to the same thing–with a comparison of the losses of power which they occasion. Unfortunately, such a comparison has never been made experimentally, because hitherto the opportunity of doing it in a demonstrative manner has been wanting, for the transmission of power to a distance belongs rather to the future than to the present time. Transmission by electricity is still in its infancy; it has only been applied on a small scale and experimentally.
Of the three other systems, transmission by means of ropes is the only one that has been employed for general industrial purposes, while compressed air and water under pressure have been applied only to special purposes, and their use has been due much more to their special suitableness for these purposes than from any considerations relative to loss of power. Thus the effective work of the compressed air used in driving the tunnels through the Alps, assuming its determination to be possible, was undoubtedly very low; nevertheless, in the present state of our appliances it is the only process by which such operations can be accomplished. The author believes that transmission by ropes furnishes the highest proportion of useful work, but that as regards a wide distribution of the transmitted power the other two methods, by air and water, might merit a preference.
* * * * *
THE HOTCHKISS REVOLVING GUN.
The Hotchkiss revolving gun, already adopted in the French navy and by other leading European nations, has been ordered for use in the German navy by the following decree of the German Emperor, dated January 11 last: “On the report made to me, I approve the adoption of the Hotchkiss revolving cannon as a part of the artillery of my navy; and each of my ships, according to their classification, shall in general be armed with this weapon in such a manner that every point surrounding the vessel may be protected by the fire of at least two guns at a minimum range of 200 meters.”
* * * * *
THALLIUM PAPERS AS OZONOMETERS.
Schoene has given the results of an extended series of experiments on the use of thallium paper for estimating approximately the oxidizing material in the atmosphere, whether it be hydrogen peroxide alone, or mixed with ozone, or perhaps also with other constituents hitherto unknown. The objection to Schoenbein’s ozonometer (potassium iodide on starch paper) and to Houzeau’s ozonometer (potassium iodide on red litmus paper) lies in the fact that their materials are hygroscopic, and their indications vary widely with the moisture of the air. Since dry ozone does not act on these papers, they must be moistened; and then the amount of moisture varies the result quite as much as the amount of ozone. Indeed, attention has been called to the larger amount of ozone near salt works and waterfalls, and the erroneous opinion advanced that ozone is formed when water is finely divided. And Boettger has stated that ozone is formed when ether is atomized; the fact being that the reaction he observed was due to the H_2O_2 always present in ether. Direct experiments with the Schoenbein ozonometer and the psychrometer gave parallel curves; whence the author regards the former as only a crude hygrometer. These objections do not lie against the thallium paper, the oxidation to brown oxide by either ozone or hydrogen peroxide not requiring the presence of moisture, and the color, therefore, being independent of the hygrometric state of the air. Moreover, when well cared for, the papers undergo no farther change of color and may be preserved indefinitely. The author prepares the thallium paper a few days before use, by dipping strips of Swedish filtering paper in a solution of thallous hydrate, and drying. The solution is prepared by pouring a solution of thallous sulphate into a boiling solution of barium hydrate, equivalent quantities being taken, the resulting solution of thallous hydrate being concentrated in vacuo until 100 c.c. contains 10 grammes Tl(OH). For use the strips are hung in the free air in a close vessel, preferably over caustic lime, for twelve hours. Other papers are used, made with a two per cent. solution. These are exposed for thirty-six hours. The coloration is determined by comparison with a scale having eleven degrees of intensity upon it. Compared with Schoenbein’s ozonometer, the results are in general directly opposite. The thallium papers show that the greatest effect is in the daytime, the iodide papers that it is at night. Yearly curves show that the former generally indicate a rise when the latter give a fall. The iodide curve follows closely that of relative humidity, clouds, and rain; the thallium curve stands in no relation to it. A table of results for the year 1879 is given in monthly means, of the two thallium papers, the ozonometer, the relative humidity, cloudiness, rain, and velocity of wind.–_G. F. B., in Ber. Berl. Chem. Ces._
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THE AUDIPHONE IN ENGLAND.
The audiphone has been recently tried in the Board School for Deaf and Dumb at Turin street, Bethnal Green, with very satisfactory results–so satisfactory that the report will recommend its adoption in the four schools which the London Board have erected for the education of the deaf and dumb. Some 20 per cent. of the pupils in deaf and dumb schools have sufficient power of hearing when assisted by the audiphone to enable them to take their places in the classes of the ordinary schools.
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CONDUCTIVITY OF MOIST AIR.
Many physical treatises still assert that moist air conducts electricity, though Silberman and others have proved the contrary. An interesting experiment bearing on this has been described lately by Prof. Marangoni. Over a flame is heated some water in a glass jar, through the stopper of which passes a bent tube to bell-jar (held obliquely), which thus gets filled with aqueous vapor. The upper half of a thin Leyden jar charged is brought into the bell-jar, and held there four or five seconds; it is then found entirely discharged. That the real cause of this, however, is condensation of the vapor on the part of the glass that is not coated with tin foil (the liquid layer acting by conduction) can be proved; for if that part of the jar be passed several times rapidly through the flame, so as to heat it to near 100 deg. C., before inserting in the bell-jar, a different effect will be had; the Leyden jar will give out long sparks after withdrawal. This is because the glass being heated no longer condenses the vapor on its surface, and there is no superficial conduction, as in the previous case.
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FLOATING PONTOON DOCK.
Considerable attention has been given for some years past to the subject of floating pontoon docks by Mr. Robert Turnbull, naval architect, of South Shields, Eng., who has devised the ingenious arrangement which forms the subject of the annexed illustration. The end aimed at and now achieved by Mr. Turnbull was so to construct floating docks or pontoons that they may rise and fall in a berth, and be swung round at one end upon a center post or cylinder–nautically known as a dolphin–projecting from the ground at a slight distance from the berth. The cylinder is in deep water, and, when the pontoon is swung and sunk to the desired depth by letting in the necessary amount of water, a vessel can be floated in and then secured. The pontoon, with the vessel on it, is then raised by pumping out the contained water until she is a little above the level of the berth. The whole is then swung round over the berth, the vessel then being high and dry to enable repairs or other operations to be conducted. For this purpose, one end of the pontoon is so formed as to enable it to fit around the cylinder, and to be held to it as to a center or fulcrum, about which the pontoon can be swung. The pontoon is of special construction, and has air-chambers at the sides placed near the center, so as to balance it. It also has chambers at the ends, which are divided horizontally in order that the operation of submerging within a berth or in shallow water may be conducted without risk, the upper chambers being afterwards supplied with water to sink the pontoon to the full depth before a vessel is hauled in. When the ship is in place, the pontoon with her is then lifted above the level of the berth in which it has to be placed, and then swung round into the berth. In some cases, the pontoon is provided with a cradle, so that, when in berth, the vessel on the cradle can be hauled up a slip with rails arranged as a continuation of the cradle-rails of the pontoon, which can be then furnished with another cradle, and another vessel lifted.
It is this latter arrangement which forms the subject of our illustration, the vessel represented being of the following dimensions: Length between perpendiculars, 350 feet; breadth, moulded, 40 feet; depth, moulded, 32 feet; tons, B. M., 2,600; tons net, 2,000. At A, in fig. 1, is shown in dotted lines a portion of the vessel and pontoon, the ship having just been hauled in and centered over the keel blocks. At B, is shown the pontoon with the ship raised and swung round on to a low level quay. Going a step further in the operation, we see at C, the vessel hauled on to the slipways on the high-level quay. In this case the cylinder is arranged so that the vessel may be delivered on to the rails or slips, which are arranged radially, taking the cylinder as the center. There may be any number of slips so arranged, and one pontoon may be made available for several cylinders at the deep water parts of neighboring repairing or building yards, in which case the recessed portion of the pontoon, when arranged around the cylinder, has stays or retaining bars fitted to prevent it leaving the cylinder when the swinging is taking place, such as might happen in a tideway.
[Illustration: Fig. 1. IMPROVED FLOATING PONTOON DRY DOCK.]
The arrangements for delivering vessels on radial slips is seen in plan at fig. 2, where A represents the river or deep water; B is the pontoon with the vessel; C being the cylinder or turning center; D is the low-level quay on to which the pontoon carrying the ship is first swung; E is the high-level quay with the slip-ways; F is an engine running on rails around the radial slips for drawing the vessels with the cradle off the pontoon, and hauling them up on to the high-level quay; and G shows the repairing shops, stores, and sheds. A pontoon attached to a cylinder may be fitted with an ordinary wet dock; and then the pontoon, before or after the vessel is upon it, can be slewed round to suit the slips up which the vessel has to be moved, supposing the slips are arranged radially. In this case, the pivot end of the pontoon would be a fixture, so to speak, to the cylinder.
The pontoon may also be made available for lifting heavy weights, by fitting a pair of compound levers or other apparatus at one end, the lifting power being in the pontoon itself. In some cases, in order to lengthen the pontoon, twenty-five or fifty foot lengths are added at the after end. When not thus engaged, those lengths form short pontoons suitable for small vessels.–_Iron_.
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WEIRLEIGH, BRENCHLEY, KENT.
Some few years since, Mr. Harrison Weir (whose drawings of natural history are known probably to a wider circle of the general public than the works of most artists), wishing to pursue his favorite study of animals and horticulture, erected on the steep hillside of the road leading from Paddock Wood to Brenchley, a small “cottage ornee” with detached studio. Afterward desiring more accommodation, he carried out the buildings shown in our illustrations. Advantage has been taken of the slope of the hill on one side, and the rising ground in the rear on the other, to increase the effect of the buildings and meet the difficulty of the levels. The two portions–old, etched, and new, shown as black–are connected together by a handsome staircase, which is carried up in the tower, and affords access to the various levels. The materials are red brick, with Bathstone dressings, and weather-tiling on the upper floors. Black walnut, pitch pine, and sequoias have been used in the staircase, and joiner’s work to the principal rooms. The principal stoves are of Godstone stone only, no iron or metal work being used. The architects are Messrs. Wadmore & Baker, of 35 Great St. Helens, E.C.; the builders, Messrs. Penn Brothers, of Pembury, Kent.–_Building News_.
[Illustration: ARTISTS HOMES NO 11 “WEIRLEIGH” BRENCHLEY, KENT. THE RESIDENCE OF HARRISON WEIR ESQ’RE WADMORE & BAKER ARCHITECTS]
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RAPID BREATHING AS A PAIN OBTUNDER IN MINOR SURGERY, OBSTETRICS, THE GENERAL PRACTICE OF MEDICINE AND OF DENTISTRY.
[Footnote: Read before the Philadelphia County Medical Society, May 12, 1880, by W. G. A. Bonwill, M.D., D.D.S., Philadelphia.]
Through the kind invitation of your directors, I am present to give you the history of “rapid breathing” as an analgesic agent, as well as my experience therein since I first discovered it. It is with no little feeling of modesty that I appear before such a learned and honorable body of physicians and surgeons, and I accept the privilege as a high compliment. I trust the same liberal spirit which prompted you to call this subject to the light of investigation will not forsake you when you have heard all I have to say and you sit in judgment thereon. Sufficient time has now elapsed since the first promulgation of the subject for the shafts of ridicule to be well nigh spent (which is the common logic used to crush out all new ideas), and it is to be expected that gentlemen will look upon it with all the charity of a learned body, and not be too hasty to condemn what they have had but little chance to investigate; and, of course, have not practiced with that success which can only come from an intelligent understanding of its application and _modus operandi_.
Knowing the history of past discoveries, I was well prepared for the crucible. I could not hope to be an exception. But, so far, the medical profession have extended me more favor than I have received at the hands of the dental profession.
My first conception of the analgesic property of a pain obtunder in contradistinction to its anaesthetic effect, which finally led to the discovery of the inhalation of common air by “rapid breathing,” was in 1855 or 1856, while performing upon my own teeth certain operations which gave me intense pain (and I could not afford to hurt myself) without a resort to ether and chloroform. These agents had been known so short a time that no one was specially familiar with their action. Without knowing whether I could take chloroform administered by myself, and at the same time perform with skill the excavation of extremely sensitive dentine or tooth-bone, as if no anaesthetic had been taken, and not be conscious of pain, was more than the experience of medical men at that time could assure me. But, having a love for investigation of the unknown, I prepared myself for the ordeal. By degrees I took the chloroform until I began to feel very plainly its primary effects, and knowing that I must soon be unconscious, I applied the excavator to the carious tooth, and, to my surprise, found no pain whatever, but the sense of touch and hearing were marvelously intensified. The small cavity seemed as large as a half bushel; the excavator more the size of an ax; and the sound was equally magnified. That I might not be mistaken, I repeated the operation until I was confident that anaesthetics possessed a power not hitherto known–that of analgesia. To be doubly certain, I gave it in my practice, in many cases with the same happy results, which saved me from the risks incident to the secondary effects of anaesthetics, and which answered for all the purposes of extracting from one to four teeth. Not satisfied with any advance longer than I could find a better plan, I experimented with the galvanic current (to and fro) by so applying the poles that I substituted a stronger impression by electricity from the nerve centers or ganglia to the peripheries than was made from the periphery to the brain. This was so much of a success that I threw aside chloroform and ether in removing the living nerve of a tooth with instruments instead of using arsenic; and for excavating sensitive caries in teeth, preparatory to filling, as well as many teeth extracted by it. But this was short-lived, for it led to another step. Sometimes I would inflict severe pain in cases of congested pulps or from its hasty application, or pushing it to do too much, when my patient invariably would draw or inhale the breath _very forcibly and rapidly_. I was struck with the repeated coincidence, and was led to exclaim: “Nature’s anaesthetic.” This then reminded me of boyhood’s bruises. The involuntary action of every one who has a finger hurt is to place it to the mouth and draw violently in the air and hold it for an instant, and again repeat it until the pain is subdued. The same action of the lungs occurs, except more powerfully, in young children who take to crying when hurt. It will be noticed they breathe very rapidly while furiously crying, which soon allays the irritation, and sleep comes as the sequel. Witness also when one is suddenly startled, how violently the breath is taken, which gives relief. The same thing occurs in the lower animals when pain is being inflicted at the hand of man.
This was advance No. 3, and so sure was I of this new discovery, that I at once made an application while removing decay from an extremely sensitive tooth. To be successful, I found I must make the patient take the start, and I would follow with a thrust from the excavator, which move would be accomplished before the lungs could be inflated. This was repeated for at least a minute, until the operation was completed, I always following immediately or synchronously with the inhalation.
This led to step No. 4, which resulted in its application to the extracting of teeth and other operations in minor surgery.
Up to this time I had believed the sole effect of the rapid inhalation was due to mere diversion of the will, and this was the only way nature could so violently exert herself–that of controlling the involuntary action of the lungs to her uses by the _safety valve_, or the voluntary movement.
The constant breathing of the patient for thirty seconds to a minute left him in a condition of body and mind resembling the effects of ether and chloroform in their primary stages. I could but argue that the prolonged breathing each time had done it; and, if so, then there must be some specific effect over and above the mere diversion by the will. To what could it be due? To the air alone, which went in excess into the lungs in the course of a minute! Why did I not then immediately grasp the idea of its broader application as now claimed for it? It was too much, gentlemen, for that hour. Enough had been done in this fourth step of conception to rest in the womb of time, until by evolution a higher step could be made at the maturity of the child. Being self-satisfied with my own baby, I watched and caressed it until it could take care of itself, and my mind was again free for another conception.
The births at first seemed to come at very short intervals; but see how long it was between the fourth and the fifth birth. It was soon after that my mind became involved in inventions–a hereditary outgrowth–and the electric mallet and then the dental engine, the parent of your surgical engine, to be found in the principal hospitals of this city, took such possession of my whole soul, that my air analgesic was left slumbering. It was not until August, 1875–nineteen years after–that it again came up in full force, without any previous warning.
This time it was no law of association that revived it; but it seemed the whispering of some one in the air–some ethereal spirit, if you please–which instituted it, and advanced the following problem: “Nitrous oxide gas is composed of the same elements as ordinary air, with a larger equivalent of oxygen, except it is a chemical compound, not a mechanical mixture, and its anaesthetic effects are said to be due to the excess of oxygen. If this be a fact, then why can you not produce a similar effect by rapid breathing for a minute, more or less, by which a larger quantity of oxygen is presented in the lungs for absorption by the blood?”
This query was soon answered by asking myself another: “If the rapid inhalation of air into the lungs does not increase the heart’s action and cause it to drive the blood in exact ratio to the inhalations, then _I can_ produce partial anaesthesia from this excess of oxygen brought about by the voluntary movements over their ordinary involuntary action of the lungs.” The next question was: Will my heart be affected by this excess of air in the lungs to such an extent that there will be a full reciprocity between them? Without making any trial of it, I argued that, while there is no other muscular movement than that of the chest as under the control of the will, and as nature has given to the will the perfect control over the lungs to supply more or less air, as is demanded by the pneumogastric nerve for the immediate wants of the economy, when the _involuntary action_ is not sufficient; and the heart not being under the control of the will, and its action never accelerated or diminished except by a specific poison, or from the general activity of the person in violent running or working, the blood is forced into the heart faster and must get rid of it, when a larger supply of oxygen is demanded and rapid breathing must occur, or asphyxia result. I was not long in deciding that the heart _would not be accelerated_ but a trifle–say a tenth–and, under the circumstances, I said: “The air _is_ an anaesthetic.”
From this rapid course of argument, I was so profoundly convinced of its truth, that without having first tried it upon my own person, I would have sat where I was, upon the curbstone, and had a tooth removed with the perfect expectation of absence of pain and of still being conscious of touch. While yet walking with my children, I commenced to breathe as rapidly as possible, and, as anticipated, found my steps growing shorter and shorter, until I came to a stand, showing to my mind clearly that my argument in advance was right, so far as locomotion was concerned; and, upon referring to my pulse, I found but little acceleration.
To what other conclusion could I arrive from this argument, with the foundation laid nineteen years before, when I established on my own person by experiment the fact of analgesia as induced from chloroform, with the many experiments in rapid respiration on tooth bone?
From this moment until its first application to the extraction of a tooth you can well imagine my suspense. That I might not fail in the very first attempt, I compelled myself and others in my household to breathe rapidly to investigate the phenomenon. This gave me some idea as to the proper method of proceeding in its administering.
The first case soon appeared, and was a perfect success, going far beyond my anticipations, for the effect was such as to produce a partial paralysis of the hands and arms to the elbow. Again and again I tried it in every case of extraction and many other experiments, doubting my own senses for a long time at a result so anomalous and paradoxical. I was reminded just here of a phenomenon which gave me additional proof–that of blowing a dull fire to revive it. For a minute or so one blows and blows in rapid succession until, rising from the effort, a sense of giddiness for a few moments so overcomes that the upright position is with difficulty maintained. In this condition you are fitted for having a tooth extracted or an abscess lanced.
Believing that I had something new to offer which might be of use to suffering humanity, I read the first article upon it Nov. 17, 1875, before the Franklin Institute. Shortly after I was invited before the Northern Medical Society of this city to address them thereon. A number of medical gentlemen have been using it in their practice, while the bulk of them have spurned it as “negative” and preposterous, without an effort at trying it, which I can _now_ very well understand.
Unless one is aware of the fact that in the use of any agent which has the power to suspend the volition, it can be taken to that point where he is still conscious of _touch and hearing_, and at the same time not cognizant of pain inflicted, the action of rapid breathing could not be understood. And I regret to say that of three-fourths of the medical men I have talked with on the subject they had not been aware of such a possibility from ether and chloroform. Until this analgesic state could be established in their minds it was impossible to convince them that the excess of oxygen, as obtained by rapid breathing, could be made to produce a similar effect. _I_ should have been as reluctant as any one to believe it, had I not personally experienced the effect while performing an operation which would otherwise have been very painful. Such a result could not well be reached by any course of reasoning.
Has it proven in my practice what has been claimed for it–a substitute for the powerful anaesthetics in minor operations in surgery? Most emphatically, yes! So completely has it fulfilled its humble mission in my office, that I can safely assert there has not been more than five per cent. of failures. I have given it under all circumstances of diseased organs, and have seen no other than the happiest results in its after effects. It may well be asked just here: Why has it not been more generally and widely used by the dental profession as well as the medical, if it is really what is claimed for it? The most satisfactory and charitable answer to be given is, the failure upon their part to comprehend the _fact_ as existing in chloroform and ether that there is such a state as analgesia; or, in other words, that the animal economy is so organized, while the sense of touch is not destroyed, but rather increased, the mind of the subject fails to perceive a sense of pain when anaesthetics are given, and the effects are manifested in the primary stage. As I before intimated, such is the knowledge possessed by most of those who administer ether and chloroform. This was enough to cause nearly every one to look upon it as a bubble or air castle. Many gentlemen told me they tried it upon themselves, and, while it affected them very seriously by giddiness, they still _retained consciousness_; and, such being the case, no effect could be produced for obtunding pain. Others told me they were afraid to continue the breathing alarmed at the vertigo induced. And the practitioner who has adopted it more effectively than any other laughed at me when I first told him of the discovery; but his intimate association with me changed his views after much explanation and argument between us.
It was hardly to be expected that without this knowledge of analgesia, and without any explanation from me as to the _modus operandi_ of rapid breathing, other than a few suggestions or directions as to how the effect was induced, even the most liberal of medical men should be able to make it effective, or have the least disposition to give it a preliminary trial upon themselves, and, of course, would not attempt it upon a patient. Notwithstanding, it found a few adherents, but only among my personal _medical_ friends, with whom I had an opportunity to explain what I believed its physiological action, and the cases of success in my own practice. To this I have submitted as among the inevitable in the calendar of discoveries of all grades.
My own profession have attempted to _ridicule_ it out of its birthright and possible existence, which style of argument is not resorted to by true logicians.
To all this I can truly say I have not for one moment faltered. I could afford to wait. The liberality of this society alone fully compensates for the seeming indisposition of the past, believing that it is proper that every advance should be confronted, and, if in time found worthy, give it God speed.
From its first conception I have diligently labored to solve its _modus operandi_, and the doubt in my own mind as to whether I could be mistaken in my observations. I asked the opinion of our best chemical teachers if air could have such effect. One attributed it to oxygen stimulation, and the other to nitrogen. Another gentleman told me the medical profession had come to the conclusion that it was possible for me to thus extract teeth, but it was due solely to my strong _personal magnetism_ (which power I was not before aware I possessed).
Now, from what I have related of the successive and natural steps which finally culminated in this process or plan of analgesia induced by an excess of ordinary air taken forcibly into the lungs above what is necessary for life, and from what I shall state as to the apparently anomalous or paradoxical effects, with its physiological action, and the simple tests made upon each of my patients, I shall trust to so convince you of its plausibility and possibility that it will be made use of in hundreds of minor operations where ether and chloroform are now used.
Aside from my assertion and that of its friends, that the effects can be produced by air alone, you must have some light shed upon the causes of its physiological action, which will appeal to your _medical_ reason.
To assign an action to any drug is difficult, and in the cases of ether and the other anaesthetics a quarter of a century still finds many conflicting opinions. This being true, you will deal leniently with me for the opinion I hold as to their analgesic action. Of course it will be objected to, for the unseen is, to a great extent, unknowable. Enough for my argument, however; it seems to suit the case very well without looking for another; and while it was based on the phenomenon resulting from many trials, and not the trials upon it as a previous theory, I shall be content with it until a better one can be found.
What is it I claim as a new discovery, and the facts and its philosophy?
I have asserted that I can produce, from rapidly breathing common air at the rate of a hundred respirations a minute, a similar effect to that from ether, chloroform, and nitrous oxide gas, in their primary stages; and I can in this way render patients sufficiently insensible to acute pain from any operation where the time consumed is not over twenty to thirty seconds. While the special senses are in partial action, the sense of pain is obtunded, and in many cases completely annulled, consciousness and general sensibility being preserved.
To accomplish this, each patient must be instructed how to act and what to expect. As simple as it may seem, there is a proper and consistent plan to enable you to reach full success. Before the patient commences to inhale he is informed of the fact that, while he will be unconscious of pain, he will know full, or partially well, every touch upon the person; that the inhalation must be vigorously kept up during the whole operation without for an instant stopping; that the more energetically and steadily he breathes, the more perfect the effect, and that if he cease breathing during the operation, pain will be felt. Fully impress them with this idea, for the very good reason that they may stop when in the midst of an operation, and the fullest effects be lost. It is obligatory to do so on account of its evanescent effects, which demand that the patient be pushed by the operator’s own energetic appeals to “go on.” It is very difficult for any person to respire more than one hundred times to the minute, as he will become by that time so exhausted as not to be able to breathe at all, as is evidenced by all who have thus followed my directions. For the next minute following the completion of the operation the subject will not breathe more than once or twice. Very few have force enough left to raise hand or foot. The voluntary muscles have nearly all been subjugated and overcome by the undue effort at forced inhalation of one hundred over seventeen, the normal standard. It will be more fully understood further on in my argument why I force patients, and am constantly speaking to them to go on.
I further claim that for the past four years, so satisfactory has been the result of this system in the extracting of teeth and deadening extremely sensitive dentine, there was no longer any necessity for chloroform, ether, or nitrous oxide in the dental office. That such teeth as cannot be extracted by its aid can well be preserved and made useful, except in a very few cases, who will not be forced to breathe.
The anaesthetics, when used in major operations, where time is needed for the operation, can be made more effective by a lesser quantity when given in conjunction with “rapid breathing.” Drs. Garrettson and Hews, who have thus tried it, tell me it takes one-half to three-fourths less, and the after effects are far less nauseating and unpleasant.
As an agent in labor where an anaesthetic is indicated, it is claimed by one who has employed it (Dr. Hews) in nearly every case for three years, he has used “rapid breathing” solely, and to the exclusion of chloroform and ether. For this I have his assertion, and have no doubt of it whatever, for if any agent could break down the action of the voluntary muscles of the parts involved, which prevent the involuntary muscles of the uterus from having their fullest effect, it is this. The very act of rapid breathing so affects the muscles of the abdomen as to force the contents of the uterus downward or outward, while the specific effect of the air at the end of a minute’s breathing leaves the subject in a semi-prostrate condition, giving the uterus full chance to act in the interim, because free of the will to make any attempt at withholding the involuntary muscles of the uterus from doing their natural work. It is self evident; and in this agent we claim here a boon of inestimable value. And not least in such cases is, there is no danger of hemorrhage, since the cause of the effect is soon removed.
In attestation of many cases where it has been tried, I have asked the mother, and, in some cases, the attendants, whether anything else had been given, and whether the time was very materially lessened, there has been but one response, and that in its favor.
Gentlemen, if we are not mistaken in this, you will agree with me in saying that it is no mean thing, and should be investigated by intelligent men and reported upon. From my own knowledge of its effects in my practice, I am bound to believe this gentleman’s record.
I further claim for it a special application in dislocations. It has certainly peculiar merits here, as the will is so nearly subjugated by it as to render the patient quite powerless to resist your effort at replacing, and at the same time the pain is subdued.
It is not necessary I should further continue special applications; when its _modus operandi_ is understood, its adaptation to many contingencies will of a sequence follow.
It is well just here, before passing to the next point of consideration, to answer a query which may arise at this juncture:
What are the successive stages of effects upon the economy from its commencement until the full effect is observed, and what proof have I that it was due to the amount of air inhaled?
The heart’s action is not increased more than from seventy (the average) to eighty and sometimes ninety, but is much enfeebled, or throwing a lesser quantity of blood. The face becomes suffused, as in blowing a fire or in stooping, which continues until the breathing is suspended, when the face becomes paler. (Have not noticed any purple as from asphyxia by a deprivation of oxygen.) The vision becomes darkened, and a giddiness soon appears. The voluntary muscles furthest from the heart seem first to be affected, and the feet and hands, particularly the latter, have a numbness at their ends, which increases, until in many cases there is partial paralysis as far as the elbow, while the limbs become fixed. The hands are so thoroughly affected that, when open, the patient is powerless to close them and _vice versa_. There is a vacant gaze from the eyes and looking into space without blinking of the eyelids for a half minute or more. The head seems incapable of being held erect, and there is no movement of the arms or legs as is usual when in great pain. There is no disposition on the part of the patient to take hold of the operator’s hand or interfere with the operation.
Many go on breathing mechanically after the tooth is removed, as if nothing had occurred. Some are aware that the tooth has been extracted, and say they felt it; others could not tell what had been accomplished. The majority of cases have an idea of what is being done, but are powerless to resist.
With the very intelligent, or those who stop to reason, I have to teach them the peculiarities of being sensible of touch and not of pain.
One very interesting case I will state. In extracting seven teeth for a lady who was very _unwilling_ to believe my statement as to touch and no pain, I first removed three teeth after having inhaled for one minute, and when fully herself, she stated that she could not understand why there was no pain while she was conscious of each one extracted; it was preposterous to believe such an effect could be possible, as her reason told her that there is connected with tooth extracting pain in the part, and of severe character, admitting, though, she felt no pain. She allowed one to be removed without anything, and she could easily distinguish the change, and exclaimed, “It is all the difference imaginable!” When the other three were extracted, there was perfect success again as with the first three.
One of the most marked proofs of the effects of rapid breathing was that of a boy of eleven years of age for whom I had to extract the upper and lower first permanent molars on each side. He breathed for nearly a minute, when I removed in about twenty seconds all four of the teeth, without a moment’s intermission or the stopping the vigorous breathing; and not a murmur, sigh, or tear afterward.
He declared there was no pain, and we needed no such assertion, for there was not the first manifestation from him that he was undergoing such a severe operation.
Another case, the same day, when I had to extract the superior wisdom teeth on both sides for an intelligent young lady of eighteen years, where I had to use two pairs of forceps on each tooth (equivalent to extraction of four teeth), and she was so profoundly affected afterward that she could; not tell me what had been done other than that I had touched her four times. She was overcome from its effects for at least a minute afterward. She was delighted.
With such severe tests I fear very little the result in any case I can have them do as I bid.
There can be no mistake that there is a _specific action_ from something. It cannot be personal magnetism or mesmeric influence exerted by me, for such cases are rare, averaging about 10 per cent, only of all classes. Besides, in mesmeric influence the time has nothing to do with it; whereas, in my cases, it cannot last over a half minute or minute at most. It cannot be fear, as such cases are generally more apt to get hurt the worse. It is not diversion of mind alone, as we have an effect above it.
There is no better way of testing whether pain has been felt than by taking the lacerated or contused gums of the patient between the index finger and thumb and making a gentle pressure to collapse the alveolar borders; invariably, they will cry out lustily, _that is pain_! This gives undoubted proof of a specific agent. There is no attempt upon my _own_ part to exert any influence over my patients in any way other than that they shall believe what I say in regard to _giving_ them _no pain_ and in the following of my orders. Any one who knows how persons become mesmerized can attest that it was not the _operator who forces them under it against their will_, but it is a peculiar state into which any one who has within themselves this temperament can _place_ themselves where any one who knows how can have control. It is not the will of the operator. I therefore dismiss this as unworthy of consideration in connection with rapid breathing.
Then you may now ask, To what do I attribute this very singular phenomenon?
Any one who followed, in the earlier part of this paper, the course of the argument in my soliloquy, after twenty years had elapsed from my observation upon myself of the analgesic effects of chloroform, can almost give something of an answer.
That you may the more easily grasp what I shall say, I will ask you, If it be possible for any human being to make one hundred inhalations in a minute and the heart’s action is not increased more than ten or twenty pulsations over the normal, what should be the effect upon the brain and nerve centers?
If the function of oxygen in common air is to set free in the blood, either in the capillaries alone, or throughout the whole of the arterial circulation, carbonic acid gas; and that it cannot escape from the system unless it do so in the lungs as it passes in the general current–except a trace that is removed by the skin and kidneys–and that the quantity of carbonic acid gas set free is in exact relation to the amount of oxygen taken into the blood, what effect _must be_ manifested where one hundred respirations in one minute are made–five or six times the normal number–while the heart is only propelling the blood a very little faster through the lungs, and _more feebly_–say 90 pulsations at most, when to be in proportion it should be 400 to 100 respirations to sustain life any length of time?
You cannot deny the fact that a definite amount of oxygen can be absorbed and is absorbed as fast as it is carried into the lungs, even if there be one hundred respirations to the minute, while the pulsations of the heart are only ninety! Nature has _made it_ possible to breathe so rapidly to meet any emergency; and we can well see its beautiful application in the normal action of both the heart and lungs while one is violently running.
What would result, and that very speedily, were the act of respiration to remain at the standard–say 18 or 20–when the heart is in violent action from this running? Asphyxia would surely end the matter! And why? The excessive exercise of the whole body is setting free from the tissues such an amount of excretive matter, and carbon more largely than all the others, that, without a relative action of the lungs to admit the air that oxygen may be absorbed, carbonic acid gas cannot be liberated through the lungs as fast as the waste carbon of the overworked tissues is being made by disassimilation from this excess of respiration.
You are already aware how small a quantity of carbonic acid in excess in the air will seriously affect life. Even 2 to 3 per cent, in a short time will prove fatal. In ordinary respiration of 20 to the minute the average of carbonic acid exhaled is 4.35.
From experiments long ago made by Vierordt–see Carpenter, p. 524–you will see the relative per cent, of carbonic acid exhaled from a given number of respirations. When he was breathing six times per minute, 5.5 per cent of the exhaled air was carbonic acid; twelve times, 4.2; twenty-four times, 3.3; forty-eight times, 3; ninety-six times, 2.6.
Remember this is based upon the whole number of respirations in the minute and not each exhalation–which latter could not be measured by the most minute method.
Let us deduct the minimum amount, 2.6 per cent, of carbonic acid when breathing ninety-six times per minute, from the average, at twenty per minute, or the normal standard, which is recorded in Carpenter, p. 524, as 4.35 per minute, and we have retained in the circulation nearly 2 per cent. of carbonic acid; that, at the average, would have passed off through the lungs without any obstruction, and life equalized; but it not having been thrown off as fast as it should have been, must, of necessity, be left to prey upon the brain and nerve centers; and as 2 to 3 per cent., we are told, will so poison the blood, life is imperiled and that speedily.
It is not necessary we should argue the point as to whether oxygen displaces carbonic acid in the tissues proper or the capillaries. The theory of Lavoisier on this point has been accepted.
We know furthermore, as more positive, that tissues placed in an atmosphere of oxygen will set free carbonic acid, and that carbonic acid has a paralyzing effect upon the human hand held in it for a short time. The direct and speedy effects of this acid upon the delicate nervous element of the brain is so well known that it must be accepted as law. One of the most marked effects is the suspension of locomotion of the legs and arms, and the direct loss of will power which must supervene before voluntary muscular inactivity, which amounts to partial paralysis in the hands or feet, or peripheral extremities of the same.
Now that we have sufficient evidence from the authorities that carbonic acid can be retained in the blood by excessive breathing, and enough to seriously affect the brain, and what its effects are when taken directly into the lungs in excess, we can enter upon what I have held as the most reasonable theory of the phenomenon produced by rapid breathing for analgesic purposes; which _theory_ was not _first_ conceived and the process made to yield to it, but the phenomenon was long observed, and from the repetition of the effects and their close relationship to that of carbonic acid on the economy, with the many experiments performed upon myself, I am convinced that what I shall now state will be found to substantiate my discovery. Should it not be found to coincide with what some may say is physiological truth, it will not invalidate the discovery itself; for of that I am far more positive than Harvey was of the discovery of the circulation of the blood; or of Galileo of the spherical shape of the earth. And I ask that it shall not be judged by my theory, but from the practice.
It should have as much chance for investigation as the theory of Julius Robert Mayer, upon which he founded, or which gave rise to the establishment of one of the most important scientific truths–“the conservation of energy,” and finally the “correlation of forces,” which theory I am not quite sure was correct, although it was accepted, and as yet, I have not seen it questioned.
In all due respect to him I quote it from the sketch of that remarkable man, as given in the _Popular Science Monthly_, as specially bearing on my discovery:
“Mayer observed while living in Java, that the _venous blood_ of some of his patients had a singularly bright red color. The observation riveted his attention; he reasoned upon it, and came to the conclusion that the brightness of the color was due to the fact that a less amount of oxidation was sufficient to keep up the temperature of the body in a hot climate than a cold one. The darkness of the venous blood he regarded as the visible sign of the energy of the oxidation.”
My observation leads me to the contrary, that the higher the temperature the more rapid the breathing to get clear of the excess of carbon, and hence more oxygenation of the blood which will arterialize the venous blood, unless there is a large amount of carbonized matter from the tissues to be taken up.
Nor must it be denied because of the reasoning as presented to my mind by some outside influence in my soliloquy when I first exclaimed, “Nature’s anaesthetic,” where the argument as to the effects of nitrous oxide gas being due to an excess of oxygen was urged, and that common air breathed in excess would do the same thing.
I am not sure that _it_ was correct, for the effects of nitrous oxide is, perhaps, due to a deprivation of mechanically mixed air.
Knowing what I do of theory and practice, I can say with assurance that there is not a medical practitioner who would long ponder in any urgent case as to the thousand and one theories of the action of remedies; but would resort to the _practical_ experience of others and his own finally. (What surgeon ever stops to ask how narcotics effect their influence?) After nearly thirty years of association with ether and chloroform, who can positively answer as to their _modus operandi?_ It is thus with nearly the whole domain of medicine. It is not yet, by far, among the sciences, with immutable laws, such as we have in chemistry. Experimentation is giving us more specific knowledge, and “practice alone has tended to make perfect.” (Then, gentlemen will not set at naught my assertion and practical results.