Mr. Conrad Cooke said, “The first and most striking principle of Hughes’ microphone is a shaking and variable contact between the two parts constituting the microphone.” “The shaking and variable contact is produced by the movable portion being effected by sound.” “Under Hughes’ system, where gas carbon was used, the instruments could not possibly work upon the principle of pressure.” “I am satisfied that it is not pressure in the sense of producing a change of resistance.” “I do not think pressure has anything to do with it.”
Professor Blyth said: “The Hughes microphone depends essentially upon the looseness or delicacy of contact.” “I have heard articulate speech with such an instrument without a diaphragm.” “There is no doubt that to a certain extent there must be a change in the number of points of surface contact when the pencil is moved.” “The action of the Hughes microphone depends more or less upon the looseness or delicacy of the contact and upon the changes in the number of points of surface contact when the pencil is moved.”
Mr. Oliver Heaviside, in _The Electrician_ of 10th February last, writes: “There should be no jolting or scraping.” “Contacts, though light, should not be loose.”
[Illustration: Fig. 2.]
A writer, who signs “W.E.H.,” in _The Electrician_ of 24th February last, says: “The variation of current arises from a variation of conductivity between the electrodes, consequent upon the variation of the closeness or pressure of contact;” and also, “there must be a variation of pressure between the electrodes when the transmitter is in action.”
It seems, then, that some scientific men agree that variation of pressure is required to produce action in a microphone, and some of them admit that a microphone with loose contacts will transmit articulate speech, while others deny it, and some admit that a jolting or shaking motion of the parts of the microphone does not interfere with articulate speech, while others say such motion would break the circuit, and cannot be relied on.
I will now describe two microphones in which there is a shaking or jolting motion, and loose contacts, and no variation of pressure of the carbons against one another, and both of these microphones when used with an induction coil and battery give most excellent articulation. One of these microphones is made as follows: Two flat plates of carbon are secured to a block of cork, insulated from each other; into a hole of each carbon a pin of carbon fits loosely, projecting above the carbons; another flat piece of carbon, having two holes in it, bridges over the two lower carbons, being kept in its place by the pins of carbon which fit loosely in the holes in it, the bottom carbons being connected with the battery; a block of cork has a flat side of it cut out so as when secured to the lower cork the carbons will not come in contact with it, yet be close enough to it to keep the carbons from falling apart. The cork covering the carbons forms a dome.
Any good telephone receiver when used in connection with this microphone, reproduces articulate speech with remarkable distinctness, especially hissing sounds, and with a loud and full tone.
A description of this microphone was published in _La Lumiere Electrique_, of 15th April, 1882, and a drawing thereof on 29th April of same year.
Another form of microphone is made as follows: Two blocks of gas carbon, C, B, each about one and a half inches long and one inch square, having each a circular hole one and a quarter inches deep and half inch in diameter; these two blocks are embedded in a block of cork, C, about one-quarter of an inch apart, these holes facing each other, each block forming a terminal of the battery and induction coil; a pencil of carbon, C, P, about three-eighths of an inch in diameter, and two inches long, having a ring of ebonite, V, fixed around its center, is placed in the holes of the two fixed blocks; the ebonite ring fitting loosely in between the two blocks so as to prevent the pencil from touching the bottom of the holes in the blocks. The space between the blocks is closed with wax, W, to exclude the air, but not to touch the ring on the pencil. A block of cork fitting close to the carbon blocks on all sides is then firmly secured to the other block of cork. The microphone should lie horizontally or at a slight angle.
This microphone produces in any good telephone perfect articulation in a loud and full tone. In these microphones there is certainly “looseness and delicacy of contact,” and there is a “jolting or shaking motion,” and it does not seem possible that there can be any “pressure of one carbon against another.”
I repeat the question I asked at the beginning of this communication, and hope that it may elicit from you, or some of our scientific men, an explanation of the theory of the action of this form of microphone.
W.C. BARNEY.
* * * * *
THE DEMBINSKI MICROPHONIC TELEPHONE TRANSMITTER.
This apparatus, which is shown by Figs. 1, 2, and 3, consists of a wooden case, A, of oblong shape, closed by a lid fixed by hinges to the top or one side of the case. The lid is actually a frame for holding a piece of wire gauze, L L, through which the sound waves from the voice can pass. In the case a flat shallow box, E F (or several boxes), is placed, on the lid of which the carbon microphone, D C (Figs. 1 and 3), which is of the ordinary construction, is placed. The box is of thin wood, coated inside with petroleum lamp black, for the purpose of increasing the resonance. It is secured in two lateral slides, fixed to the case. The bottom of the box is pierced with two openings, resembling those in a violin (Fig. 2). Lengthwise across the bottom are stretched a series of brass spiral springs, G G G, which are tuned to a chromatic scale. On the bottom of the case a similar series of springs, not shown, are secured. The apparatus is provided with an induction coil, J, which is connected to the microphone, battery, and telephone receiver (which may be of any known description) in the usual manner.
[Illustration: Fig. 1.]
The inventors claim that the use of the vibrating springs give to the transmitter an increased power over those at present in use. They state that the instrument has given very satisfactory results between Ostende and Arlon, a distance of 314 kilometers (about 200 miles). It does not appear, however, that microphones of the ordinary Gower-Bell type, for example, were tried in competition with the new invention, and in the absence of such tests the mere fact that very satisfactory results were obtained over a length of 200 miles proves very little. With reference to a statement that whistling could be very clearly heard, we may remark that experience has many times proved that the most indifferent form of transmitter will almost always respond well and even powerfully to such forms of vibration.–_Electrical Review_.
[Illustration: Fig. 2.]
[Illustration: Fig. 3.]
* * * * *
NEW GAS LIGHTERS.
We are going to make known to our readers two new styles of electric lighters whose operation is sure and quick, and the use of which is just as economical as that of those quasi-incombustible little pieces of wood that we have been using for some years under the name of matches.
[Illustration: Fig. 1.–MODE OF USING THE GAS LIGHTER.]
The first of these is a portable apparatus designed for lighting gas burners, and is based upon the calorific properties of the electric spark produced by the induction bobbin. Its internal arrangement is such as to permit of its being used with a pile of very limited power and dimensions. The apparatus has the form of a rod of a length that may be varied at will, according to the height of the burner to be lighted, and which terminates at its lower part in an ebonite handle about 4 centimeters in width by 20 in length (Fig. 1). This handle is divided into two parts, which are shown isolatedly in Fig. 2, and contains the pile and bobbin. The arrangement of the pile, A, is kept secret, and all that we can say of it is that zinc and chloride of silver are employed as a depolarizer. It is hermetically closed, and carries at one of its extremities a disk, B, and a brass ring, C, attached to its poles and designed to establish a communication between the pile and bobbin when the two parts of the apparatus are screwed together. To this end, two elastic pieces, D and E, fit against B and C and establish a contact. It is asserted that the pile is capable of being used 25,000 times before it is necessary to recharge it. H is an ebonite tube that incloses and protects the induction bobbin, K, whose induced wire communicates on the one hand with the brass tube, L, and on the other with an insulated central conductor, M, which terminates at a point very near the extremity of the brass tube. The currents induced in this wire produce a series of sparks between the tube, L, and the rod, M, which light the gas when the extremity of the apparatus is placed in proximity with the burner.
[Illustration: Fig. 2. MECHANISM OR THE INDUCTION SPARK GAS LIGHTER.]
The ingenious and new part of the system lies in the mode of exciting the induced currents. When the extremity of the tube, L, is brought near the gas burner that is to be lighted, it is only necessary to shove the botton, F, from left to right in order to produce a _limited_ number of sparks sufficient to effect the lighting. The motion of the button has not for effect, as might be believed, the closing of the circuit of the pile upon the inducting circuit of the bobbin. In fact in its normal position, the vibrator is distant from its contact, and the closing of the circuit would produce no action. The motion of F produces a _mechanical_ motion of the spring of the vibrator, which latter acts for a few instants and produces a certain number of contacts that give rise to an equal number of sparks. Owing to this arrangement, the expenditure of electric energy required by each lighting is limited; and, an another hand, the vibrator, which would be incapable of operating if it had to be set in motion by the direct current from the pile, can be actuated _mechanically_. As the motion of the vibrator is derived from the hand of the operator, and not from the pile, it will be comprehended that the latter can, everything being equal, produce a larger number of lightings than an ordinary bobbin and vibrator.
[Illustration: Fig. 3.–INCANDESCENT GAS LIGHTER.]
Dr. Naret’s _Fiat Lux_ (Fig. 3) is simpler in its operation, and cheaper of application, since it takes its current from the ordinary piles that supply domestic call-bells. It consists essentially of a fine platinum wire supported by a tilting device in connection with the two poles of a pile composed of three Leclanche elements. Upon exerting a vertical pressure on the button placed to the left of the apparatus, either directly or by means of a cord, we at the same time turn the cock and cause the platinum spiral to approach, and the latter then becomes incandescent as a consequence of the closing of the circuit of the pile. After the burner is lighted it is only necessary to leave the apparatus to itself. The cock remains open, the spiral recedes from the burner, the circuit opens anew, and the burner remains lighted until the gas is turned off. This device, then, is particularly appropriate in all cases where there is a pressing need of light, for a single maneuver suffices to open the cock and effect a lighting of the burner.–_La Nature_.
* * * * *
DISTRIBUTION OF HEAT WHICH IS DEVELOPED BY FORGING.
On the 8th of June. 1874, Tresca presented to the French Academy some considerations respecting the distribution of heat in forging a bar of platinum, and stated the principal reasons which rendered that metal especially suitable for the purpose. He subsequently experimented, in a similar way, with other metals, and finally adopted Senarmont’s method for the study of conductibility. A steel or copper bar was carefully polished on its lateral faces, and the polished portion covered with a thin coat of wax. The bar thus prepared was placed under a ram, of known weight, P, which was raised to a height, H, where it was automatically released so as to expend upon the bar the whole quantity of work _T=PH,_ between the two equal faces of the ram and the anvil. A single shock sufficed to melt the wax upon a certain zone and thus to limit, with great sharpness, the part of the lateral faces which had been raised during the shock to the temperature of melting wax. Generally the zone of fusion imitates the area comprised between the two branches of an equilateral hyperbola, but the fall can be so graduated as to restrict this zone, which then takes other forms, somewhat different, but always symmetrical. If A is the area of this zone, b the breadth of the bar, d the density of the metal, c its capacity for heat, and t-t0 the excess of the melting temperature of wax over the surrounding temperature, it is evident that, if we consider A as the base of a horizontal prism which is raised to the temperature t, the calorific effect may be expressed by:
Ab x d x C(t-t0);
and on multiplying this quantity of heat by 425 we find, for the value of its equivalent in work,
T’ = 425 AbdC(t-t0).
On comparing T’ to T we may consider the experiment as a mechanical operation, having a minimum of:
T’/T = (425/PH)AbdC(t-t0).
After giving diagrams and tables to illustrate the geometrical disposition of the areas of fusion, Tresca feels justified in concluding that the development of heat depends upon the form of the faces and the intensity of the shock; that the points of greatest heat correspond to the points of greatest flow of the metal, and that this flow is really the mechanical phenomenon which gives rise to the calorific phenomenon; that for action sufficiently energetic and for bars of sufficient dimensions, about 0.8 of the labor expended on the blow may be found again in the heat; that the figures formed in the melted wax for shocks of less intensity furnish a kind of diagram of the distribution of the heat and of the deformation in the interior of the bar, but that the calculation of the coefficient of efficiency does not yield satisfactory results in the case of moderate blows.–_Comptes Rendus_.
* * * * *
TIN IN CANNED FOODS.
[Footnote: Read at an evening meeting of the Pharmaceutical Society, March 5, 1884.]
By PROFESSOR ATTFIELD, F.R.S., ETC.
From time to time, during the past twelve years, paragraphs have appeared in newspapers and other periodicals tending in effect to warn the public at least against the indiscriminate use of canned foods. And whenever there has been any foundation in fact for such cautions, it has commonly rested on the alleged presence and harmfulness of tin in the food. At the worst, the amount of tin present has been absurdly small, affording an opportunity for one literary representative of medicine to state that before a man could be seriously affected by the tin, even if it occurred in the form of a compound of the metal, he would have to consume at a meal ten pounds of the food containing the largest amount of tin ever detected.
But the greatest proportions of tin thus referred to are, according to my experiments, far beyond those ever likely to be actually present in the food itself in the form of a compound of tin; present, that is to say, on account of the action of the fluids or juices of the food on the tin of the can. Such action and such consequent solution of the tin, and consequent admixture of a possibly assimilable compound of tin with the food, in my opinion never occurs to an extent which in relation to health has any significance whatever. The occurrence of tin, not as a compound, but as the metal itself, is, if possible, still less important.
During the last fifteen years I have frequently examined canned foods, not only with respect to the food itself as food, and to the process of canning, but with regard to the relation of the food to, or the influence if any of the metal of, the can itself. So lately as within the past two or three months I have examined sixteen varieties of canned food for metals, with the following results:
Decimal parts of
a grain of tin
(or other foreign
metal) present in
Name of article a quarter of a lb. examined.
Salmon none.
Lobsters none.
Oysters 0.004
Sardines none.
Lobster paste none.
Salmon paste none.
Bloater paste 0.002
Potted beef none.
Potted tongue none.
Potted “Strasbourg” none.
Potted ham 0.002
Luncheon tongue 0.003
Apricots 0.007
Pears 0.003
Tomatoes 0.007
Peaches 0.004
These proportions of metal are, I say, undeserving of serious notice. I question whether they represent more than the amounts of tin we periodically wear off tin saucepans in preparing food–a month ago I found a trace of tin in water which had been boiled in a tin kettle–or the silver we wear off our forks and spoons. There can be little doubt that we annually pass through our systems a sensible amount of such metals, metallic compounds, and other substances that do not come under the denomination of food; but there is no evidence that they ever did or are ever likely to do harm or occasion us the slightest inconvenience. Harm is far more likely to come to us from noxious gases in the air we breathe than from foreign substances in the food we eat.
But whence come the much less minute amounts of tin–still harmless, be it remembered–which have been stated to be occasionally present in canned foods? They come from the minute particles of metal chipped off from the tin sheets in the operations of cutting, bending, or hammering the parts of the can, or possibly melted off in the operations necessary for the soldering together of the joints of the can. Some may, perhaps, be cut, off by the knife in opening a can. At all events I not unfrequently find such minute particles of metal on carefully washing the external surfaces of a mass of meat just removed from a can, or on otherwise properly treating canned food with the object of detecting such particles. The published processes for the detection of tin in canned food will not reveal more than the amounts stated in the table, or about those amounts; that is to say, a few thousandths or perhaps two or three hundredths of a grain, if this precaution be adopted. If such care be not observed, the less minute amounts may be found. I did not detect any metallic particles in the twelve samples of canned food just mentioned, but during the past few years I have occasionally found small pieces of metal, perhaps amounting in some of the cases to a few tenths of a grain per pound. Now and then small shot-like pieces of tin, or possibly solder, may be met with; but no one has ever found, to my knowledge, such a quantity of actual metallic tin, tinned iron, or solder as, from the point of view of health, can have any significance whatever.
The largest amount of tin I ever detected in actual solution in food was in some canned soup, containing a good deal of lemon juice. It amounted to only three-hundredths of a grain in a half pint of the soup as sent to table. Now, Christison says that quantities of 18 to 44 grains of the very soluble chloride of tin were required to kill dogs in from one to four days. Orfila says that several persons on one occasion dressed their dinner with chloride of tin, mistaking it for salt. One person would thus take not less than 20 to 30 grains of this soluble compound of tin. Yet only a little gastric and bowel disturbance followed, and from this all recovered in a few days. Pereira says that the dose of chloride of tin as an antispasmodic and stimulant is from 1/16 to 1/2 a grain repeated two or three times daily. Probably no article of canned food, not even the most acid fruit, if in a condition in which it can be eaten, has ever contained, in an ordinary table portion, as much of a soluble salt of tin as would amount to a harmless or useful medicinal dose.
Metallic particles of tin are without any effect on man. A thousand times the quantity ever found in a can of tinned food would do no harm.
Food as acid as say ordinary pickles would dissolve tin. Some manufacturers once proposed using tin stoppers to their bottles of pickles. But the tin was slowly dissolved by the acid of the vinegar. These pickles, however, had a distinctly nasty “metallic” flavor. The idea was abandoned. Probably any article of food containing enough tin to disagree with the system would be too nasty to eat. Purchasers of food may rest assured that the action taken by this firm would be that usually followed. It is not to the interest of manufacturers or other venders to offend the senses of purchasers, still less to do them actual harm, even if no higher motive comes into force.
In the early days of canning, it is just possible that the use of “spirits of salt” in soldering may have resulted in the presence of a little stannous, plumbous, or other chloride in canned food; but such a fault would soon be detected and corrected, and as a matter of fact, resin-soldering is to my knowledge more generally employed–indeed, for anything I know to the contrary, is exclusively employed–in canning food. Any resin that trained access would be perfectly harmless. It is just possible, also, that formerly the tin itself may have contained lead, but I have not found any lead in the sheet tin used for canning of late years.
In conclusion: 1. I have never been able to satisfy myself that a can of ordinary tinned food contains even a useful medicinal dose of such a true soluble _compound_ of tin as is likely to have any effect on man. 2. As for the metal itself, that is the filings or actual metallic particles or fragments, one ounce is a common dose as a vermifuge; harmless even in that quantity to man, and not always so harmful as could be desired to the parasites for whose disestablishment it is administered. One ounce might be contained in about four hundredweight of canned food. 3. If a possibly harmful quantity of a soluble compound, of tin be placed in a portion of canned food, the latter will be so nasty and so unlike any ordinary nasty flavor, so “metallic,” in fact, that no sane person will eat it. 4. Respecting the globules of solder (lead and tin) that are occasionally met with in canned food, I believe most persons detect them in the mouth and remove them, as they would shots in game. But if swallowed, they do no harm. Pereira says that metallic lead is probably inert, and that nearly a quarter of a pound has been administered to a dog without any obvious effects. He goes on to say that as it becomes oxidized it occasionally acquires activity, quoting Paulini’s statement that colic was produced in a patient who had swallowed a leaden bullet. To allay alarm in the minds of those who fear they might swallow pellets of solder, I may add that Pereira cites Proust for the assurance that an alloy of tin and lead is less easily oxidized than pure lead. 5. Unsoundness in meat does not appear to promote the corrosion or solution of tin. I have kept salmon in cans till it was putrid, testing it occasionally for tin. No trace of tin was detected. Nevertheless, food should not be allowed to remain for a few days, or even hours, in saucepans, metal baking pans, or opened tins or cans, otherwise it _may_ taste metallic. 6. Unsound food, canned or uncanned, may, of course, injure health, and where canned food really has done harm, the harm has in all probability been due to the food and not to the can. 7. What has been termed idiosyncrasy must also be borne in mind. I know a man to whom oatmeal is a poison. Some people cannot eat lobsters, either fresh or tinned. Serious results have followed the eating of not only oatmeal or shell fish, but salmon and mutton; _hydrate_ (misreported _nitrate_) of tin being gratuitously suggested as being contained in the salmon in one case. Possibly there were cases of idiosyncrasy in the eater, possibly the food was unsound, possibly other causes altogether led to the results, but certainly, to my mind, the tin had nothing whatever to do with the matter.
In my opinion, given after well weighing all evidence hitherto forthcoming, the public have not the faintest cause for alarm respecting the occurrence of tin, lead, or any other metal in canned foods.–_Phar. Jour, and Trans., March 8, 1884, p. 719_.
[In reference to Prof. Attfield’s statement contained in the closing paragraph, we remark: It is well known that mercury is an ingredient of the solder used in some canning concerns, as it makes an easier melting and flowing solder. In THE SCIENTIFIC AMERICAN for May 27, 1876, in a report of the proceedings of the New York Academy of Science, will be seen the statement of Prof. Falke, who found metallic mercury in a can of preserved corn beef, together with a considerable quantity of albuminate of mercury.–EDS. S.A.]
* * * * *
VILLA AT DORKING.
The house shown in the illustration was lately erected from the designs of Mr. Charles Bell, F.R.I.B.A. Although sufficiently commodious, the cost has been only about 1,050_l_.–_The Architect_.
[Illustration: SUGGESTIONS IN ARCHTECTURE.–AN ENGLISH COTTAGE. COST, $5,250.]
* * * * *
Valerianate of cerium in the vomiting of pregnancy is recommended by Dr. Blondeau in a communication to the _Societe de Therapeutique_. He gives it in doses of 10 centigrammes three times a day.–_Medical Record_.
* * * * *
[Illustration: ARM CHAIR IN THE LOUVRE COLLECTION, PARIS; FLENISH RENAISSANCE.–_From The Workshop._]
* * * * *
TECHNICAL EDUCATION IN AMERICA.
If there is one point more than another in which the exuberant youth and vitality of the American nation is visible it is in that of education, the provision for which is on a most generous scale, carried out with a determination at which the older countries of the Eastern Hemisphere have only arrived by slow degrees and painful experience. Of course the Americans, being young, and having come to the fore, so to speak, full-fledged, have been able to profit by the lessons which they have derived from their neighbors–though it is none the less to their credit that they have profited so well and so quickly. Technical and industrial education has received a more general recognition, and been developed more rapidly, than the general education of the country, partly for the reason that there is no uniform system of the latter throughout the States, but that each individual State and Territory does that which is right in its own eyes. The principal reason, however, is that to possess the knowledge, how to work is the first creed of the American, who considers that the right to obtain that knowledge is the birthright of every citizen, and especially when the manual labor has to be supplemented by a vigorous use of brains. The Americans as a rule do not like heavy or coarse manual labor, thinking it beneath them; and, indeed, when they can get Irish and Chinese to do it for them, perhaps they are not far wrong. But the idea of idleness and loafing is very far from the spirit of the country, and this is why we see the necessity for industrial education so vigorously recognized, both as a national duty, and by private individuals or communities of individuals.
From whatever source it is provided, technical education in the United States comes mainly within the scope of two classes of institutions, viz., agricultural and mechanical colleges; although the two are, as often as not, combined under one establishment, and particularly it forms the subject of a national grant. Indeed, it may be said that the scope of industrial education embraces three classes: the farmer, the mechanic, and the housekeeper; and in the far West we find that provision is made for the education of these three classes in the same schools, it being an accepted idea in the newer States that man and woman (the housekeeper) are coworkers, and are, therefore, entitled to equal and similar educational privileges. On the other hand, in the more conservative East and South, we find that the sexes are educated distinct from each other. In the East, there is generally, also, a separation of subjects. In Massachusetts, for instance, the colleges of agriculture and mechanics are separate affairs, the students being taught in different institutions, viz., the agricultural college and the institute of technology. In Missouri the separation is less defined, the School of Mines and Metallurgy being the, only part that is distinct from the other departments of the University.
One of the chief reasons for the necessity for hastening the extension of technical education in America was the almost entire disappearance of the apprenticeship system, which, in itself, is mainly due to the subdivision of labor so prevalent in the manufacture of everything, from pins to locomotives. The increased use of machinery, the character of which is such as often to put an end to small enterprises, has promoted this subdivision by accumulating workmen in large groups. The beginner, confining himself to one department, is soon able to earn wages, and so he usually continues as he begins. Mr. C.B. Stetson has written on this subject with great force and earnestness, and it will not be amiss to quote a sentence as to the advantages enjoyed by the technically workman. He says that “it is the rude or dexterous workman, rather than the really skilled one, who is supplanted by machinery. Skilled labor requires thinking; but a machine never thinks, never judges, never discriminates. Though its employment does, indeed, enable rude laborers to do many things now which formerly could only be done by dexterous workmen, it is clear that its use has decidedly increased the relative demand for skilled labor as compared with unskilled, and there is abundant room for an additional increase, if it is true, as declared by the most eminent authority, that the power now expended can be readily made to yield three or four times its present results, and ultimately ten or twenty times, when masters and workmen can be had with sufficient intelligence and skill for the direction and manipulation of the tools and machinery that would be invented.”
The establishment of colleges and universities by the aid of national grants has depended very much for their character upon the industrial tendencies of the respective States, it being understood that the land grants have principally been given to those of the newer States and Territories which required development, although some of the institutions of the older States on the Atlantic seaboard have also been recipients of the same fund, which in itself only dates from an act of Congress in 1862. In California and Missouri, both States abounding in mineral resources, there are courses in mining and metallurgy provided in the institutions receiving national aid. In the great grain-producing sections of the Mississippi Valley the colleges are principally devoted to agriculture, whereas the characteristic feature of the Iowa and Kansas schools is the prominence given to industries.
We need not devote attention to the aims and arrangements of the agricultural colleges proper, but will pass at once to those which deal with the mechanical arts, dealing first of all with those that are assisted by the national land grant. Taking them alphabetically, we have first the State Agricultural College of Colorado, in the mechanical and drawing department of which shops for bench work in wood and iron and for forging have been recently erected, this institution being one of the newest in America. In the Illinois Industrial University the student of mechanical engineering receives practice in five shops devoted to pattern-making, blacksmithing, moulding and founding, benchwork for iron, and machine tool-work for iron. In the first shop the practice consists of planing, chiseling, turning, and the preparation of patterns for casting. The ordinary blacksmithing operations take place in the second shop, and those of casting in the third. In the fourth there is, first of all, a course of freehand benchwork, and afterward the fitting of parts is undertaken. In the fifth shop all the fundamental operations on iron by machinery are practiced, the actual work being carefully outlined beforehand by drawings. This department of the University consists, in point of fact, of three separate schools, destined to qualify the student for every kind of engineering–mining, railway, mechanical, and architectural. In addition to the shops and machine rooms, there are well furnished cabinets of geological and mineralogical specimens, chemical laboratories for assaying and metallurgy, stamp mill, furnaces, etc., and, in fact, every known vehicle for practical instruction. The school of architecture prepares students for the building profession. Among the subjects in this branch are office work and shop practice, constructing joints in carpentry and joinery, cabinet making and turning, together with modeling in clay. The courses in mathematics, mechanics and physics are the same as those in the engineering school; but the technical studies embrace drawing from casts, wood, stone, brick, and iron construction, turners’ work, slating, plastering, painting, and plumbing, architectural drawing and designing, the history and aesthetics of architecture, estimates, agreements specification, heating, lighting, draining, and ventilation. The student’s work from scale drawing occupies three terms, carpentry and joinery being taught in the first year, turning and cabinet making in the second, metal and stone work in the third. A more condensed course, known as the builder’s course, is given to those who can only stop one year. The machine shop has a steam engine of 16 horse power, two engines and three plain lathes, a planer, a large drill press, a pattern shop, a blacksmith’s shop, all of the machinery having been built on the spot. The carpenter’s shop is likewise supplied with necessary machine tools, such as saws, planers, tenoning machine, whittlers, etc., the power being furnished by the machine shop. At the date of the last University report, there were 41 students in the courses of mechanical engineering, 41 in those of civil engineering, 3 in mining engineering, and 14 in architecture. Tuition is free in all the University classes, though each student has to pay a matriculation fee of $10, and the incidental expenses amount to about $23 annually. He is charged for material used or apparatus broken, but not for the ordinary wear and tear of instruments. It should be mentioned that the endowment of the Illinois Industrial University is from scrip received from the Government for 480,000 acres of land, of which 454,460 have been sold for $319,178. The real estate of the University, partly made up by donations and partly by appropriations made in successive sessions by the State of Illinois, is estimated at $450,000.
The Purdue University in Indiana, named after its founder, who gave $150,000, which was supplemented by another $50,000 from the State and a bond grant of 390,000 acres, also provides a very complete mechanical course, with shop instruction, divided as follows:
Bench working in wood for 12 weeks, or 120 hours. Wood-turning ” 4 ” ” 40 “
Pattern-making ” 12 ” ” 120 ” Vise-work in iron ” 10 ” ” 100 ” Forging in iron and steel ” 18 ” ” 180 ” Machine tool-work in iron ” 20 ” ” 200 “
The course in carpentry and joinery embraces: 1. Exercising in sawing and planing to dimensions. 2 Application, or box nailed together. 3 Mortise and tenon joints; a plain mortise and tenon; an open dovetailed mortise and tenon (dovetailed halving); a dovetailed keyed mortise and tenon. 4. Splices. 5. Common dovetailing. 6. Lap dovetailing and rabbeting. 7. Blind or secret dovetail. 8. Miter-box. 9. Carpenter’s trestle. 10. Panel door. 11. Roof truss. 12. Section of king-post truss roof. 13. Drawing model.
The course in wood turning includes: 1. Elementary principles: first, straight turning; second, cutting in; third, convex curves with the chisel; fourth, compound curves formed with the gouge. 2. File and chisel handles. 3. Mallets. 4. Picture frames (chuck work). 5. Card receiver (chuck work). 6. Watch safe (chuck work). 7. Ball.
In the pattern-making course the student is supposed to have some skill in bench and lathe work, which will be increased; the direct object being to teach what forms of pattern are in general necessary, and how they must be constructed in order to get a perfect mould from them. The character of the work differs each year. For instance, for the last year, besides simpler patterns easily drawn from the sand, such as glands, ball-cranks, etc., there were a series of flanged pipe-joints for 21/2 in. pipes, including the necessary core boxes; also pulley patterns from 6 in. to 10 in. diameter, built in segments for strength, and to prevent warping and shrinkage; and, lastly, a complete set of patterns for a three horse-power horizontal steam engine, all made from drawings of the finished piece. In the vise work in iron, the chief requirements are these: 1, given a block of cast iron 4 in. by 2 in. by 11/2 in. in thickness, to reduce the thickness 1/4 in. by chipping, and then finishing with the file; 2, to file a round hole square; 3, to file a round hole into elliptical; 4, given a 3 in. cube of wrought iron, to cut a spline 3 in. by 3/8 in. by 1/4 in., and second, when the under side is a one half round hollow–these two cuts involve the use of the cope chisel and the round nose chisel, and are examples of very difficult chipping; 5, round tiling or hand-vise work; 6, scraping; 7, special examples of fitting. In the forging classes are elementary processes, driving, bending, and upsetting; courses in welding; miscellaneous forging; steel forging, including hardening and tempering in all its details.
It is worth mentioning that in the industrial art school of the Purdue University there were 13 of the fair sex as students, besides one in the chemical school, and two going through the mechanical courses just detailed, showing that the scope of woman’s industry is less limited in America than in England. The Iowa State Agricultural College has also two departments of mechanical and civil engineering, the former including a special course of architecture. The workshop practice, which occupies three forenoons of 21/2 hours each per week, is, however, of more general character, and is not pursued with such a regard to any special calling as in the case of the Purdue University.
The Kansas State Agricultural College has a course of carpentry, though designed rather more to meet the everyday necessities of a farmer’s life. In fact, all the students are obliged to attend these classes, and take the same first lessons in sawing, planing, lumber dressing, making mortises, tenons, and joints, and in general use of tools–just the kind of instruction that every English lad should have before he is shipped off to the Colonies. This farmer’s course in the Kansas College provides for a general training in mechanical handiwork, but facilities are given also to those who wish to follow out the trade, and special instruction is provided in the whole range of work, from framing to stair-building, as also in iron work, such as ordinary forging, filing, tempering, etc. Of the students attending this college, 75 percent, are from farmers’ homes, and the majority of the remainder from the families of mechanics and tradesmen.
The State College of Maine provides courses for both civil and mechanical engineers, and has two shops equipped according to the Russian system. Forge and vise work are taught in them, though it is not the object of the college so much to teach the details of any one trade as to qualify students by general knowledge to undertake any of them afterward. A much more complete and thorough technical education is given in the Massachusetts Institute of Technology at Boston, where there are distinct classes for civil, mechanical, mining, geological, and architectural engineering. The following are the particulars of the instruction in the architectural branch, which commences in the student’s second year, with Greek, Roman, and Mediaeval architectural history, the Orders and their applications, drawing, sketching, and tracing, analytic geometry, differential calculus, physics, descriptive geometry, botany, and physical geography. In the third year the course is extended to the theory of decoration, color, form, and proportion; conventionalism, symbolism, the decorative arts, stained glass, fresco painting, tiles, terra-cotta, original designs, specifications, integral calculus, strength of materials, dynamics, bridges and roofs, stereotomy. In the fourth year the student is turned out a finished architect, after a course of the history of ornament, the theory of architecture, stability of structure, flow of gases, shopwork (carpentry), etc.
The number of students in this very comprehensive Institute of Technology was, by the latest report, 390, of whom 138 were undergoing special courses, 39 were in the schools of mechanical art, and 49 in the Lowell School of Practical Design. Tuition is charged at the rate of 200 dols. for the institute proper, and 150 dols. for the mechanical schools, the average expenses per student being about 254 dols. There are 10 free scholarships, of which two are given for mechanical art. The Lowell School has been established by the trustee of the Lowell Institute to afford free technical education, under the auspices of the Institute of Technology, to both sexes–a large number of young women availing themselves of it in connection with their factory work at Lowell. The courses include practical designs for manufactures, and the art of making patterns for prints, delaines, silks, paperhangings, carpets, oilcloth, etc., and the school is amply provided with pattern looms. Indeed, the whole of the appliances for practical teaching at the Institute are on such a complete scale that at the risk of being a little tedious it is as well to enumerate them. They comprise laboratories devoted to chemistry, mineralogy, metallurgy, and industrial chemistry; there are also microscopic, spectroscopic, and organic laboratories. In other branches there are laboratories and museums of steam engineering, mining, and metallurgy, biology and architecture, together with an observatory, much used in connection with geodesy and practical astronomy. The steam engineering laboratory provides practice in testing, adjusting, and managing steam machinery. The appliances in connection with mining and metallurgy include a five-stamp battery, Blake crusher, automatic machine jigs, an engine pulverizer, a Root and a Sturtevant blower, with blast reverberating, wasting, cupellation, and fusion furnaces, and all other means for reducing ores. The architectural museum contains many thousand casts, models, photographs, and drawings. The shops for handwork are large and well arranged, and include a vise-shop, forge shop, machine, tool, and lathe shops, foundry, rooms for pattern making, weaving, and other industrial institutions. The vise-shop contains four heavy benches, with 32 vises attached, giving a capacity for teaching 128 students the course every ten weeks, or 640 in a year of fifty weeks. The forge-shop has eight forges. The foundry has 16 moulding benches, an oven for core baking, and a blast furnace of one-half ton capacity. The pattern-weaving room is provided with five looms, one of them in 20-harness, and 4-shuttle looms, and another an improved Jacquard pattern loom. It may safely be said that there is nor an establishment in the world better equipped for industrial and technical education than this Institute of Massachusetts.–_London Building News_.
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IVORY GETTING SCARCE.–The stock of ivory in London is estimated at about forty tons in dealers’ private warehouses, whereas formerly they usually held about one hundred tons. One fourth of all imported into England goes to the Sheffield cutlers. No really satisfactory substitute for ivory has been found, and millions await the discoverer of one. The existing substitutes will not take the needed polish.
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THE ANAESTHETICS OF JUGGLERS.
Fakirs are religious mendicants who, for the purpose of exciting the charity of the public, assume positions in which it would seem impossible that they could remain, submit themselves to fearful tortures, or else, by their mode of living, their abstinence, and their indifference to inclement weather and to external things, try to make believe that, owing to their sanctity, they are of a species superior to that of common mortals.
In the Indies, these fakirs visit all the great markets, all religious fetes, and usually all kinds of assemblages, in order to exhibit, themselves. If one of them exhibits some new peculiarity, some curious deformity, a strange posture, or, finally, any physiological curiosity whatever that surpasses those of his confreres, he becomes the attraction of the fete, and the crowd surrounds him, and small coin and rupees begin to fall into his bowl.
Fakirs, like all persons who voluntarily torture themselves, are curious examples of the modifications that will, patience, and, so to speak, “art” can introduce into human nature, and into the sensitiveness and functions of the organs. If these latter are capable of being improved, of having their functions developed and of acquiring more strength (as, for example, the muscles of boxers, the breast of foot racers, the voice of singers, etc.), these same organs, on the contrary, can be atrophied or modified, and their functions be changed in nature. It is in such degradation and such degeneration of human nature that fakirs excel, and it is from such a point of view that they are worth studying.
We may, so to speak, class these individuals according to the grades of punishments that they inflict upon themselves, or according to the deformities that they have caused themselves to undergo. But, as we have already said, the number of both of these is extremely varied, each fakir striving in this respect to eclipse his fellows. It is only necessary to open a book of Indian travel to find descriptions of fakirs in abundance; and such descriptions might seem exaggerated or unlikely were they not so concordant. The following are a few examples:
_Immovable fakirs_.–The number of these is large. They remain immovable in the spot they have selected, and that too for an exceedingly long period of time. An example of one of these is cited who remained standing for twelve years, his arms crossed upon his breast, without moving and without lying or sitting down. In such cases charitable persons always take it upon themselves to prevent the fakir from dying of starvation. Some remain sitting, immovable, and apparently lifeless, while others, who lie stretched out upon the ground, look like corpses. It may be easily imagined what a state one of these beings is in after a few months or years of immobility. He is extremely lean, his limbs are atrophied, his body is black with filth and dust, his hair is long and dishevelled, his beard is shaggy, his finger and toe nails have become genuine claws, and his aspect is frightful. This, however, is a character common to all fakirs.
We may likewise class among the immovables those fakirs who cause themselves to be interred up to the neck, and who remain thus with their head sticking out of the ground either during the entire time the fair or fete lasts or for months and years.
_Anchylotic Fakirs_.–The number of fakirs who continue to hold one or both arms outstretched is very large in India. The following description of one of them is given by a traveler: “He was a goussain–a religious mendicant–who had dishevelled hair and beard, and horrible tattooings upon his face, and, what was most hideous, was his left arm, which, withered and anchylosed, stuck up perpendicularly from the shoulder. His closed hand, surrounded by straps, had been traversed by the nails, which, continuing to grow, had bent like claws on the other side. Finally, the hollow of this hand, which was filled with earth, served as a pot for a small sacred myrtle.”
Other fakirs hold their two arms above their head, the hands crossed, and remain perpetually in such a position. Others again have one or both arms extended. Some hang by their feet from the limb of a tree by means of a cord, and remain head downward for days at a time, with their face uncongested and their voice clear, counting their beads and mumbling prayers.
One of the most remarkable peculiarities of fakirs is the faculty that certain of them possess of remaining entirely buried in vaults and boxes, and inclosed in bags, etc., for weeks and months, and, although there is a certain deceit as regards the length of their absolute abstinence, it nevertheless seems to be a demonstrated fact that, after undergoing a peculiar treatment, they became plunged into a sort of lethargy that allows them to remain for several days or weeks without taking food. Certain fakirs that have been interred under such conditions have, it appears, passed ten months or a year in their grave.
_Tortured Fakirs_.–Fakirs that submit themselves to tortures are very numerous. Some of them perform exercises analogous to those of the Aissaoua. Mr. Rousselet, in his voyage to the Indies, had an opportunity of seeing some of these at Bhopal, and the following is the picturesque description that he gives of them: “I remarked some groups of religious mendicants of a frightfully sinister character. They were Jogins, who, stark naked and with dishevelled hair, were walking about, shouting, and dancing a sort of weird dance. In the midst of their contortions they brandished long, sharp poniards, of a special form, provided with steel chains. From time to time, one of these hallucinated creatures would drive the poniard into his body (principally into the sides of his chest), into his arms, and into his legs, and would only desist when, in order to calm his apparent fury, the idlers who were surrounding him threw a sufficient number of pennies to him.”
At the time of the feast of the Juggernaut one sees, or rather one _did_ see before the English somewhat humanized this ceremony, certain fakirs suspended by their flesh from iron hooks placed along the sides of the god’s car. Others had their priests insert under their shoulder blades two hooks, that were afterward fixed to a long pole capable of pivoting upon a post. The fakirs were thus raised about thirty feet above ground, and while being made to spin around very rapidly, smilingly threw flowers to the faithful. Others, again, rolled over mattresses garnished with nails, lance-points, poniards, and sabers, and naturally got up bathed in blood. A large number cause 120 gashes (the sacred number) to be made in their back and breast in honor of their god. Some pierce their tongue with a long and narrow poniard, and remain thus exposed to the admiration of the faithful. Finally, many of them are content to pass points of iron or rods made of reed through folds in their skin. It will be seen from this that fakirs are ingenious in their modes of exciting the compassion and charity of the faithful.
Elsewhere, among a large number of savage tribes and half-civilized peoples, we find aspirants to the priesthood of the fetiches undergoing, under the direction of the members of the religious caste that they desired to enter, ordeals that are extremely painful. Now, it has been remarked for a long time that, among the neophytes, although all are prepared by the same hands, some undergo these ordeals without manifesting any suffering, while others cannot stand the pain, and so run away with fright. It has been concluded from this that the object of such ordeals is to permit the caste to make a selection from among their recruits, and that, too, by means of anesthetics administered to the chosen neophytes.
In France, during the last two centuries, when torturing the accused was in vogue, some individuals were found to be insensible to the most fearful tortures, and some even, who were plunged into a species of somnolence or stupefaction, slept in the hands of the executioner.
What are the processes that permit of such results being reached? Evidently, we cannot know them all. A certain number are caste, sect, or family secrets. Many are known, however, at least in a general way. The processes naturally vary, according to the object to be attained. Some seem to consist only in an effort of the will. Thus, those fakirs who remain immovable have no need of any special preparation to reach such a result, and the same is the case with those who are interred up to the neck, the will alone sufficing. Fakirs probably pass through the same phases that invalids do who are forced to keep perfectly quiet through a fracture or dislocation. During the first days the organism revolts against such inaction, the constraint is great, the muscles contract by starts, and then the patient gets used to it; the constraint becomes less and less, the revolt of the muscles becomes less frequent, and the patient becomes reconciled to his immobility. It is probable that after passing several months or years in a state of immobility fakirs no longer experience any desire to change their position, and even did they so desire, it would be impossible owing to the atrophy of their muscles and the anchylosis of their joints.
Those fakirs who remain with one or several limbs immovable and in an abnormal position have to undergo a sort of preparation, a special treatment; they have to enter and remain two or three mouths in a sort of cage or frame of bamboo, the object of which is to keep the limb that is to be immobilized in the position that it is to preserve. This treatment, which is identical with the one employed by surgeons for curing affections of the joints, has the effect of soldering or anchylosing the articulation. When such a result is reached, the fakir remains, in spite of himself and without fatigue, with outstretched arms, and, in order to cause them to drop, he would have to undergo a surgical operation.
As for those voluntary tortures that cause an effusion of blood, the insensibility of those who are the victims of it is explainable when we reflect that _India_ is _the_ country _par excellence_ of anaesthetic plants. It produces, notably, Indian hemp and poppy, the first of which yields hashish and the other opium. Now it is owing to these two narcotics, taken in a proper dose, either alone or combined according to a formula known to Hindoo fakirs and jugglers, but ignored by the lower class, that the former are able to become absolutely insensible themselves or make their adepts so.
[Illustration: INDIAN FAKIRS IN VARIOUS POSITIONS.]
There is, especially, a liquor known in the Indian pharmacopoeia under the name of _bang_, that produces an exciting intoxication accompanied with complete insensibility. Now the active part of bang consists of a mixture of opium and hashish. It was an analogous liquor that the Brahmins made Indian widows take before leading them to the funeral pile. This liquor removed from the victims not only all consciousness of the act that they were accomplishing, but also rendered them insensible to the flames. Moreover, the dose of the anaesthetic was such that if, by accident, the widow had escaped from the pile (something that more than once happened, thanks to English protection), she would have died through poisoning. Some travelers in Africa speak of an herb called _rasch_, which is the base of anaesthetic preparations employed by certain Arabian jugglers and sorcerers.
It was hashish that the Old Man of the Mountain, the chief of the sect of Assassins, had recourse to for intoxicating his adepts, and it was, it is thought, by the use of a virulent solanaceous plant–henbane, thornapple, or belladonna–that he succeeded in rendering them insensible. We have unfortunately lost the recipe for certain anaesthetics that were known in ancient times, some of which, such as the _Memphis stone_, appear to have been used in surgical operations. We are also ignorant of what the wine of myrrh was that is spoken of in the Bible.
We are likewise ignorant of the composition of the anaesthetic soap, the use of which became so general in the 15th and 16th centuries that, according to Taboureau, it was difficult to torture persons who were accused. The stupefying recipe was known to all jailers, who, for a consideration, communicated it to prisoners. It was this use of anaesthetics that gave rise to the rule of jurisprudence according to which partial or general insensibility was regarded as a certain sign of sorcery. We may cite a certain number of preparations, which vary according to the country, and to which is attributed the properly of giving courage and rendering persons insensible to wounds inflicted by the enemy. In most cases alcohol forms the base of such beverages, although the _maslach_ that Turkish soldiers drink just before a battle contains none of it, on account of a religious precept. It consists of different plant-juices, and contains, especially, a little opium. Cossacks and Tartars, just before battle, take a fermented beverage in which has been infused a species of toadstool (_Agaricus muscarius_), and which renders them courageous to a high degree.
As well known, the old soldiers of the First Empire taught the young conscripts that in order to have courage and not feel the blows of the enemy, it was only necessary to drink a glass of brandy into which gunpowder had been poured.–_La Nature_.
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[SCHOOL OF MINES QUARTERLY.]
THE DEPOSITION OF ORES.
By J.S. NEWBERRY.
MINERAL VEINS.
In the _Quarterly_ for March, 1880, a paper was published on “The Origin and Classification of Ore Deposits,” which treated, among other things, of mineral veins. These were grouped in three categories, namely: 1. Gash Veins; 2. Segregated Veins; 3. Fissure Veins; and were defined as follows:
_Gash Veins_.–Ore deposits confined to a single bed or formation of _limestone_, of which the joints, and sometimes planes of bedding, enlarged by the solvent power of atmospheric water carrying carbonic acid, and forming crevices, galleries, or caves, are lined or filled with ore leached from the surrounding rock, e.g., the lead deposits of the Upper Mississippi and Missouri.
_Segregated Veins_.–Sheets of quartzose matter, chiefly lenticular and conforming to the bedding of the inclosing rocks, but sometimes filling irregular fractures across such bedding, found only in metamorphic rocks, limited in extent laterally and vertically, and consisting of material indigenous to the strata in which they occur, separated in the process of metamorphism, e.g., quartz ledges carrying gold, copper, iron pyrites, etc., in the Alleghany Mountains, New England, Canada, etc.
_Fissure Veins_.–Sheets of metalliferous matter filling fissures caused by subterranean force, usually in the planes of faults, and formed by the deposit of various minerals brought from a lower level by water, which under pressure and at a high temperature, having great solvent power, had become loaded with matters leached from different rocks, and deposited them in the channels of escape as the pressure and temperature were reduced.
Since that article was written, a considerable portion of several years has been spent by the writer continuing the observations upon which it was based. During this time most of the mining centers of the Western States and Territories, as well as some in Mexico and Canada, were visited and studied with more or less care. Perhaps no other portion of the earth’s surface is so rich in mineral resources as that which has been covered by these observations, and nowhere else is to be found as great a variety of ore deposits, or those which illustrate as well their mode of formation. This is so true that it maybe said without exaggeration that no one can intelligently discuss the questions that have been raised in regard to the origin and mode of formation of ore bodies without transversing and studying the great mining belt of our Western States and Territories.
The observations made by the writer during the past four years confirm in all essentials the views set forth in the former article in the _Quarterly_, and while a volume might be written describing the phenomena exhibited by different mines and mining districts, the array of facts thus presented would be, for the most part, simply a re-enforcement of those already given.
The present article, which must necessarily be short, would hardly have a _raison d’etre_ except that it affords an opportunity for an addition which should be made to the classes of mineral veins heretofore recognized in this country, and it seems called for by the recent publication of theories on the origin of ore deposits which are incompatible with those hitherto presented and now held by the writer, and which, if allowed to pass unquestioned, might seem to be unquestionable.
BEDDED VEINS.
Certain ore deposits which have recently come under my observation appear to correspond very closely with those that Von Cotta has taken as types of his class of “bedded veins,” and as no similar ones have been noticed by American writers on ore deposits they have seemed to me worthy of description.
These are zones or layers of a sedimentary rock, to the bedding of which they are conformable, impregnated with ore derived from a foreign source, and formed long subsequent to the deposition of the containing formation. Such deposits are exemplified by the Walker and Webster, the Pinon, the Climax, etc., in Parley’s Park, and the Green-Eyed Monster, and the Deer Trail, at Marysvale, Utah. These are all zones in quartzite which have been traversed by mineral solutions that have by substitution converted such layers into ore deposits of considerable magnitude and value.
The ore contained in these bedded veins exhibits some variety of composition, but where unaffected by atmospheric action consists of argentiferous galena, iron pyrites carrying gold, or the sulphides of zinc and copper containing silver or gold or both. The ore of the Walker and Webster and the Pinon is chiefly lead-carbonate and galena, often stained with copper-carbonate. That of the Green Eyed Monster–now thoroughly oxidized as far as penetrated–forms a sheet from twenty to forty feet in thickness, consisting of ferruginous, sandy, or talcose soft material carrying from twenty to thirty dollars to the ton in gold and silver. The ore of the Deer Trail forms a thinner sheet containing considerable copper, and sometimes two hundred to three hundred dollars to the ton in silver.
The rocks which hold these ore deposits are of Silurian age, but they received their metalliferous impregnation much later, probably in the Tertiary, and subsequent to the period of disturbance in which they were elevated and metamorphosed. This is proved by the fact that in places where the rock has been shattered, strings of ore are found running off from the main body, crossing the bedding and filling the interstices between the fragments, forming a coarse stock-work.
Bedded veins may be distinguished from fissure veins by the absence of all traces of a fissure, the want of a banded structure, slickensides, selvages, etc.; from gash veins and the floors of ore which often accompany them, as well as from segregated veins, they are distinguished by the nature of the inclosing rock and the foreign origin of the ore. Sometimes the plane of junction between two contiguous sheets of rock has been the channel through which has flowed a metalliferous solution, and the zone where the ore has replaced by substitution portions of one or both strata. These are often called blanket veins in the West, but they belong rather to the category of contact deposits as I have heretofore defined them. Where such sheets of ore occupy by preference the planes of contact between adjacent strata, but sometimes desert such planes, and show slickensided walls, and banded structure, like the great veins of Bingham, Utah, these should be classed as true fissure veins.
THEORIES OF ORE DEPOSIT.
The recently published theories of the formation of mineral veins, to which I have alluded, are those of Prof. Von Groddek[1] and Dr. Sandberger,[2] who attribute the filling of veins to exudations of mineral solutions from the wall rocks (i.e., lateral secretions), and those of Mr. S.F. Emmons,[3] and Mr. G.F. Becker,[4] who have been studying, respectively, the ore deposits of Leadville and of the Comstock, by whom the ores are credited to the leaching of adjacent _igneous_ rocks.
[Footnote 1: Die Lehre von den Lagerstatten der Erze, von Dr. Albrecht von Groddek, Leipzig. 1879.]
[Footnote 2: Untersuchungen uber Erzgange, von Fridolin Sandberger, Weisbaden, 1882.]
[Footnote 3: Geology and Mining Industry of Leadville, Annual Report, Director U.S. Geol. Surv., 1881.]
[Footnote 4: Geology of the Comstock Lode and Washoe District, G.F. Becker, Washington, 1883.
It is but justice to Messrs. Becker and Emmons to say that theirs are admirable studies, thorough and exhaustive, of great interest and value to both mining engineers and geologists, and most creditable to the authors and the country. No better work of the kind has been done anywhere, and it will detract little from its merit even if the views of the authors on the theoretical question of the sources of the ores shall not be generally adopted.]
The lack of space must forbid the full discussion of these theories at the present time, but I will briefly enumerate some of the facts which render it difficult for me to accept them.
First, _the great diversity of character exhibited by different sets of fissure veins which cut the same country rock_ seems incompatible with any theory of lateral secretion. These distinct systems are of different ages, of diversified composition, and have evidently drawn their supply of material from different sources. Hundreds of cases of this kind could be cited, but I will mention only a few; among others the Humboldt, the Bassick, and the Bull Domingo, near Rosita and Silver Cliff, Colorado. These are veins contained in the same sheet of eruptive rock, but the ores are as different as possible. The Humboldt is a narrow fissure carrying a thin ore streak of high grade, consisting of sulphides of silver, antimony, arsenic, and copper; the Bassick is a great conglomerate vein containing tellurides of silver and gold, argentiferous galena, blende, and yellow copper; the Bull Domingo is also a great fissure filled with rubbish containing ore chimneys of galena with tufts of wire silver. I may also cite the Jordan, with its intersecting and yet distinct and totally different veins; the Galena, the Neptune, and the American Flag, in Bingham Canon, Utah; and the closely associated yet diverse system of veins the Ferris, the Washington, the Chattanooga, the Fillmore, etc., in Bullion Canon at Marysvale. In these and many other groups which have been examined by the writer, the same rocks are cut by veins of different ages, having different bearings, and containing different ores and veinstones. It seems impossible that all these diversified materials should have been derived from the same source, and the only rational explanation of the phenomena is that which I have heretofore advocated, the ascent of metalliferous solutions from different and deep seated sources.
Another apparently unanswerable argument against the theory of lateral secretion is furnished by the cases _where the same vein traverses a series of distinct formations, and holds its character essentially unaffected by changes in the country rock_. One of many such may be cited in the Star vein at Cherry Creek, Nevada, which, nearly at right angles to their strike, cuts belts of quartzite, limestone, and slate, maintaining its peculiar character of ore and gangue throughout.
This and all similar veins have certainly been filled with material brought from a distance, and not derived from the walls.
LEACHING OF IGNEOUS ROCKS.
The arguments against the theory that mineral veins have been produced by the leaching of superficial _igneous_ rocks are in part the same as those already cited against the general theory of lateral secretion. They may be briefly summarized as follows:
1. Thousands of mineral veins in this and other countries occur in regions remote from eruptive rocks. Into this category come most of those of the eastern half of the Continent, viz., Canada, New England, the Alleghany belt, and the Mississippi Valley. Among those I will refer only to a few selected to represent the greatest range of character, viz., the Victoria lead mine, near Sault Ste. Marie, the Bruce copper mine on Lake Huron, the gold-bearing quartz veins of Madoc, the Gatling gold vein of Marmora, the Acton and the Harvey Hill copper mines of Canada, the copper veins of Ely, Vermont, and of Blue Hills, Maine, the silver-bearing lead veins of Newburyport, Mass.; most of the segregated gold veins of the Alleghany belt, the lead veins of Rossie, Ellenville, and at other localities farther South; the copper bearing veins of Virginia, North Carolina, and Tennessee; the veins carrying argentiferous galena in Central Kentucky and in Southern Illinois; the silver, copper, and antimony veins of Arkansas; and the lead and zinc deposits of Missouri and the Upper Mississippi.
In these widely separated localities are to be found fissure, segregated, and gash veins, and a great diversity of ores, which have been derived, sometimes from the adjacent rocks–as in the segregated veins of the Alleghany belt and the gash veins of the Mississippi region–and in other cases–where they are contained in true fissure veins–from a foreign source, but all deposited without the aid of superficial igneous rocks, either as contributors of matter or force.
2. In the great mineral belt of the Far West, where volcanic emanations are so abundant, and where they have certainly played an important part in the formation of ore deposits, the great majority of veins are not in immediate contact with trap rocks, and they could not, therefore, have furnished the ores.
A volume might be formed by a list of the cases of this kind, but I can here allude to a few only, most of which I have myself examined, viz.:
_(a.)_ The great ore chambers of the San Carlos Mountains in Chihuahua, the largest deposits of ore of which I have any knowledge. These are contained in heavy beds of limestone, which are cut in various places by trap dikes, which, as elsewhere, have undoubtedly furnished the stimulus to chemical action that has resulted in the formation of the ore bodies, but are too remote to have supplied the material.
_(b.)_ The silver mines of Santa Eulalia, in Chihuahua, from which during the last century one hundred and twelve millions of dollars were taken, opened on ore deposits situated in Cretaceous limestones like those of San Carlos, and apparently similar ore-filled chambers; an igneous rock caps the hills in the vicinity, but is nowhere in contact or even proximity to the ore bodies. (See Kimball, _Amer. Jour. Sci,_. March, 1870.)
_(c.)_ The great chambers of Tombstone, and the copper veins of the Globe District, the Copper Queen, etc., in Arizona.
_(d.)_ The large bodies of silver-ore at Lake Valley, New Mexico; chambers in limestone, like _c_.
_(e.)_ The Black Hawk group of gold mines, the Montezuma, Georgetown, and other silver mines in the granite belt of Colorado.
_(f.)_ The great group of veins and chambers in the Bradshaw, Lincoln, Star, and Granite districts of Southern Utah, where we find a host of veins of different character in limestone or granite, with no trap to which the ores can be credited.
_(g.)_ The Crismon Mammoth vein of Tintic.
_(h.)_ The group of mines opened on the American Fork, on Big and Little Cottonwood, and in Parley’s Park, including the Silver Bell, the Emma, the Vallejo, the Prince of Wales, the Kessler, the Bonanza, the Climax, the Pinon, and the Ontario. (The latter, the greatest silver mine now known in the country, lies in quartzite, and the trap is near, but not in contact with the vein.)
_(i.)_ In Nevada, the ore deposits of Pioche, Tempiute, Tybo, Eureka, White Pine, and Cherry Creek, on the east side of the State, with those of Austin, Belmont, and a series too great for enumeration in the central and western portions.
_(j.)_ In California, the Bodie, Mariposa, Grass Valley, and other mines.[1]
_(k.)_ In Idaho, those of the Poor Man in the Owyhee district, the principal veins of the Wood River region, the Ramshorn at Challis, the Custer and Charles Dickens, at Bonanza City, etc.
[Footnote 1: See Redmond’s Report _(California Geol. Survey Mining Statistics, No 1),_ where seventy-seven mines are enumerated, of which three are said to be in “porphyritic schist,” all the others in granite, mica schist, clay, slate, etc.]
In nearly all these localities we may find evidence not only that the ore deposits have not been derived from the leaching of igneous rocks, but also that they have not come from those of any kind which form the walls of the veins.
The gold-bearing quartz veins of Deadwood are so closely associated with dikes of porphyry, that they may have been considered as illustrations of the potency of trap dikes in producing concentration of metals. But we have conclusive evidence that the gold was there in Archaean times, while the igneous rocks are all of modern, probably of Tertiary, date. This proof is furnished by the “Cement mines” of the Potsdam sandstone. This is the beach of the Lower Silurian sea when it washed the shores of an Archaean island, now the Black Hills. The waves that produced this beach beat against cliffs of granite and slate containing quartz veins carrying gold. Fragments of this auriferous quartz, and the gold beaten out of them and concentrated by the waves, were in places buried in the sand beach in such quantity as to form deposits from which a large amount of gold is now being taken. Without this demonstration of the origin and antiquity of the gold, it might very well have been supposed to be derived from the eruptive rock.
Strong arguments against the theory that the leaching of superficial igneous rocks has supplied the materials filling mineral veins, are furnished by the facts observed in the districts where igneous rocks are most prevalent, viz.: (1.) _Such districts are proverbially barren of useful minerals_. (2.) _Where these occur, the same sheet of rock may contain several systems of veins with different ores and gangues._
The great lava plain of Snake River, the Pedrigal country of eastern Oregon, Northern California and Mexico are without valuable ore deposits. The same may be said of the Pancake Range and other mountain chains of igneous rock in Nevada, while the adjacent ranges composed of sedimentary rocks are rich in ore deposits of various kinds. A still stronger case is furnished by the Cascade Mountains, which, north of the California line, are composed almost exclusively of erupted material, and yet in all this belt, so far as now known, not a single valuable mine has been opened. In contrast with this is the condition of things in California, where the Sierra Nevada is composed of metamorphic rocks which have been shown to be the repositories of vast quantities of gold, silver, and copper. Cases belonging to this category may be found at Rosita and Silver Cliff, where the diversity in the ores of the mines already enumerated can hardly be reconciled with the theory of a common origin. At Lake City the prevailing porphyry holds the veins of the Ute and Ulay and the Ocean Wave mines, which are similar, and the Hotchkiss, the Belle, etc., entirely different.
We have no evidence that any volcanic eruption has drawn its material from zones or magmas especially rich in metals or their ores, and on the contrary, volcanic districts, like those mentioned, and regions, such as the Sandwich Islands, where the greatest, eruptions have taken place, are poorest in metalliferous deposits.
All the knowledge we have of the subject justifies the inference that most of the igneous rocks which have been poured out in our Western Territories are but fused conditions of sediments which form the substructure of that country. Over the great mineral belt which lies between the Sierra Nevada and the front range of the Rocky Mountains, and extends not only across the whole breadth of our territory, but far into Mexico, the surface was once underlain by a series of Palaeozoic sedimentary strata not less than twenty to thirty thousand feet in thickness; and beneath these, at the sides, and doubtless below, were Archaeun rocks, also metamorphosed sediments. Through these the ores of the metals were generally though sparsely distributed. In the convulsions which have in recent times broken up this so long quiet and stable portion of the earth’s crust (and which have resulted in depositing in thousands of cracks and cavities the ores we now mine), portions of the old table-land were in places set up at high angles forming mountain chains, and doubtless extending to the zone of fusion below. Between these blocks of sedimentary rocks oozed up through the lines of fracture quantities of fused material, which also sometimes formed mountain chains; and it is possible and even probable that the rocks composing the volcanic ridges are but phases of the same materials that form the sedimentary chains There is, therefore, no _a priori_ reason why the leaching of one group should furnish more ore than the other; but, as a matter of fact, the unfused sediments are much the richer in ore deposits. This can only be accounted for, in my judgment, by supposing that they have been the receptacles of ore brought from a foreign source; and we can at least conjecture where and how gathered. We can imagine, and we are forced to conclude, that there has been a zone of solution below, where steam and hot water, under great pressure, have effected the leaching of ore-bearing strata, and a zone of deposition above, where cavities in pre-existent solidified and shattered rocks became the repositories of the deposits made from ascending solutions, when the temperature and pressure were diminished. Where great masses of fused material were poured out, these must have been for along time too highly heated to become places of deposition; so long indeed that the period of active vein formation may have passed before they reached a degree of solidification and coolness that would permit their becoming receptacles of the products of deposition. On the contrary, the masses of unfused and always relatively cool sedimentary rocks which form the most highly metalliferous mountain ranges (White Pine, Toyabe, etc.) were, throughout the whole period of disturbance, in a condition to become such repositories. Certainly highly heated solutions forced by an irresistible _vis a tergo_ through rocks of any kind down in the heated zone, would be far more effective leaching agents than cold surface water with feeble solvent power, moved only by gravity, percolating slowly through superficial strata.
Richthofen, who first made a study of the Comstock lode, suggests that the mineral impregnation of the vein was the result of a process like that described, viz., the leaching of deep-seated rocks, perhaps the same that inclose the vein above, by highly heated solutions which deposited their load near the surface. On the other hand, Becker supposes the concentration to have been effected by surface waters flowing laterally through the igneous rocks, gathering the precious metals and depositing them in the fissure, as lateral secretion produces the accumulation of ore in the limestone of the lead region. But there are apparently good reasons for preferring the theory of Richthofen: viz., first, the veinstone of the Comstock is chiefly quartz, the natural and common precipitate of _hot_ waters, since they are far more powerful solvents of silica than cold. On the contrary, the ores deposited from lateral secretion, as in the Mississippi lead region, at low temperature contain comparatively little silica; second, the great mineral belt to which reference has been made above is now the region where nearly all the hot springs of the continent are situated. It is, in fact, a region conspicuous for the number of its hot springs, and it is evident that these are the last of the series of thermal phenomena connected with the great volcanic upheavals and eruptions, of which this region has been the theater since the beginning of the Tertiary age. The geysers of Yellowstone Park, the hot springs of the Wamchuck district in Oregon, the Steamboat Springs of Nevada, the geysers of California, the hot springs of Salt Lake City, Monroe, etc., in Utah, and the Pagosa in Colorado, are only the most conspicuous among thousands of hot springs which continue in action at the present time. The evidence is also conclusive that the number of hot springs, great as it now is in this region, was once much greater. That these hot springs were capable of producing mineral veins by material brought up in and deposited from their waters, is demonstrated by the phenomena observable at the Steamboat Springs, and which were cited in my former article as affording the best illustration of vein formation.
The temperature of the lower workings of the Comstock vein is now over 150 deg.F., and an enormous quantity of hot water is discharged through the Sutro Tunnel. This water has been heated by coming in contact with hot rocks at a lower level than the present workings of the Comstock lode, and has been driven upward in the same way that the flow of all hot springs is produced. As that flow is continuous, it is evident that the workings of the Comstock have simply opened the conduits of hot springs, which are doing to-day what they have been doing in ages past, but much less actively, i.e., bringing toward the surface the materials they have taken into solution in a more highly heated zone below. Hence it seems much more natural to suppose that the great sheets of ore-bearing quartz now contained in the Comstock fissure were deposited by ascending currents of hot alkaline waters, than by descending currents of those which were cold and neutral The hot springs are there, though less copious and less hot than formerly, and the natural deposits from hot waters are there. Is it not more rational to suppose with Richthofen that these are related as cause and effect, rather than that cold water has leached the ore and the silica from the walls near the surface? Mr. Becker’s preference for the latter hypothesis seems to be due to the discovery of gold and silver in the igneous rocks adjacent to the vein, and yet, except in immediate contact with it, these rocks contain no more of the precious metals than the mere trace which by refined tests may be discovered everywhere. If, as we have supposed, the fissure was for a long time filled with a hot solution charged with an unusual quantity of the precious metals, nothing would be more natural than that the wall rocks should be to some extent impregnated with them.
It will perhaps illuminate the question to inquire which of the springs and water currents of this region are now making deposits that can be compared with those which filled the Comstock and other veins. No one who has visited that country will hesitate to say the hot and not the cold waters. The immense silicious deposits, carrying the ores of several metals, formed by the geysers of the Yellowstone, the Steamboat Springs, etc., show what the hot waters are capable of doing; but we shall search in vain for any evidence that the cold surface waters have done or can do this kind of work.
At Leadville the case is not so plain, and yet no facts can be cited which really _prove_ that the ore deposits have been formed by the leaching of the overlying porphyry rather than by an outflow of heated mineral solutions along the plane of junction between the porphyry and the limestone. Near this plane the porphyry is often thoroughly decomposed, is somewhat impregnated with ore, and even contains sheets of ore within itself; but remote from the plane of contact with the limestone, it contains little diffused and no concentrated ore. It is scarcely more previous than the underlying limestones, and why a solution that could penetrate and leach ores from it should be stopped at the upper surface of the blue limestone is not obvious; nor why the plane of junction between the porphyry and the _blue limestone_ should be the special place of deposit of the ore.
If the assays of the porphyry reported by Mr. Emmons were accurately made, and they shall be confirmed by the more numerous ones necessary to settle the question, and the estimates he makes of the richness of that rock be corroborated, an unexpected result will be reached, and, as I think, a remarkable and exceptional case of the diffusion of silver and lead through an igneous rock be established.
It is of course possible that the Leadville porphyries are only phases of rocks rich in silver, lead, and iron, which underlie this region, and which have been fused and forced to the surface by an ascending mass of deeper seated igneous rock; but even if the argentiferous character of the porphyry shall be proved, it will not be proved that such portions of it as here lie upon the limestone have furnished the ore by the descending percolation of cold surface waters. Deeper lying masses of this same silver, lead, and iron bearing rock, digested in and leached by _hot_ waters and steam under great pressure, would seem to be a more likely source of the ore. If the surface porphyry is as rich in silver as Mr. Emmous reports it to be, it is too rich, for the rock that has furnished so large a quantity of ores as that which formed the ore bodies which I saw in the Little Chief and Highland Chief mines, respectively 90 feet and 162 feet thick, should be poor in silver and iron and lead, and should be rotten from the leaching it had suffered, but except near the ore-bearing contact it is compact and normal.
Such a digested, kaolinized, desilicated rock as we would naturally look for we find in the porphyry _near the contact_; and its condition there, so different from what it is remote from the contact, seems to indicate an exposure to local and decomposing influences, such indeed as a hot chemical solution forced up from below along the plane of contact would furnish.
It is difficult to understand why the upper portions of the porphyry sheet should be so different in character, so solid and homogeneous, with no local concentrations or pockets of ore, if they have been exposed to the same agencies as those which have so changed the under surface.
Accepting all the facts reported by Mr. Emmons, and without questioning the accuracy of any of his observations, or depreciating in any degree the great value of the admirable study he has made of this difficult and interesting field, his conclusion in regard to the source of the ore cannot yet be insisted on as a logical necessity. In the judgment of the writer, the phenomena presented by the Leadville ore deposits can be as well or better accounted for by supposing that the plane of contact between the limestone and porphyry has been the conduit through which heated mineral solutions coming from deep seated and remote sources have flowed, removing something from both the overlying and underlying strata, and by substitution depositing sulphides of lead, iron, silver, etc., with silica.
The ore deposits of Tybo and Eureka in Nevada, of the Emma, the Cave, and the Horn Silver [1] mines in Utah, have much in common with those of Leadville, and it is not difficult to establish for all of the former cases a foreign and deep seated source of the ore. The fact that the Leadville ore bodies are sometimes themselves excavated into chambers, which has been advanced as proof of the falsity of the theory here advocated, has no bearing on the question, as in the process of oxidation of ores which were certainly once sulphides, there has been much change of place as well as character; currents of water have flowed through them which have collected and redeposited the cerusite in sheets of “hard carbonate” or “sand carbonate,” and have elsewhere produced accumulations of kerargyrite, perhaps thousands of years after the deposition of the sulphide ores had ceased and the oxidation had begun. In the leaching and rearrangement of the ore bodies, nothing would be more natural than that accumulations in one place should be attended by the formation of cavities elsewhere.
[Footnote 1: The Horn Silver ore body lies in a fault fissure between a footwall of limestone and a hanging wall of trachyte, and those who consider the Leadville ores as teachings of the overlying porphyry would probably also regard the ore of the Horn Silver mine as derived from the trachyte hanging wall; but three facts oppose the acceptance of this view, viz., let, the trachyte, except in immediate contact with the ore body, seems to be entirely barren; 2d, the Horn Silver ore “chimney,” perhaps fifty feet thick, five hundred feet wide, and of unknown depth, is the only mass of ore yet found in a mile of well marked fissure; and 3d, the Carbonate mine opened near by in a strong fissure with a bearing at right angles to that of the Horn Silver, and lying entirely within the trachyte, yields ore of a totally different kind. Both are opened to the depth of seven hundred feet with no signs of change or exhaustion. If the ore were derived from the trachyte, it should be at least somewhat alike in the two mines, should be more generally distributed in the Horn Silver fissure, and might be expected to give out at, no great depth.
If deposited by solutions coming from deep and different sources, the observed differences in character would be natural; it would accumulate as we find it in the channels of outflow, and would be as time will probably prove it, perhaps variable in quantity, but indefinitely continuous in depth.]
Another question which suggests itself in reference to the Leadville deposits is this: If the Leadville ore was once a mass of sulphides derived from the overlying porphyry by the percolation of surface waters, why has the deposit ceased? The deposition of galena, blende, and pyrite in the Galena lead mines still continues. If the leaching of the Leadville porphyry has not resulted in the formation of alkaline sulphide solutions, and the ore has come from the porphyry in the condition of carbonate of lead, chloride of silver, etc., then the nature of the deposition was quite different from that of the similar ones of Tybo, Eureka, Bingham, etc., which are plainly gossans, and indeed is without precedent. But if the process was similar to that in the Galena lead region, and the ores were originally sulphides, their formation should have continued and been detected in the Leadville mines.
For all these reasons the theory of Mr. Emmons will be felt to need further confirmation before it is universally adopted.
From what has gone before it must not be inferred that lateral secretion is excluded by the writer from the list of agencies which have filled mineral veins, for it is certain that the nature of the deposit made in the fissure has frequently been influenced by the nature of the adjacent wall rock. Numerous cases may be cited where the ores have increased or decreased in quantity and richness, or have otherwise changed character in passing from one formation to another; but even here the proof is generally wanting that the vein materials have been furnished by the wall rocks opposite the places where they are found.
The varying conductivity of the different strata in relation to heat and electricity may have been an important factor. Trap dikes frequently enrich veins where they approach or intersect them, and they have often been the _primum mobile_ of vein formation, but chiefly, if not only, by supplying heat, the mainspring of chemical action. The proximity of heated masses of rock has promoted chemical action in the same way as do the Bunsen burners or the sand baths in the laboratory; but no case has yet come under my observation where it was demonstrable that the filling of a fissure vein had been due to secretion from igneous or sedimentary wall rocks.
In the Star District of Southern Utah the country rock is Palaeozoic limestone, and it is cut by so great a number and variety of mineral veins that from the Harrisburg, a central location, a rifle shot would reach ten openings, all on as many distinct and different veins (viz., the Argus, Little Bilk, Clean Sweep, Mountaineer, St. Louis, Xenia, Brant, Kannarrah, Central, and Wateree). The nearest trap rock is half a mile or more distant, a columnar dike perhaps fifteen feet in thickness, cutting the limestone vertically. On either side of this dike is a vein from one to three feet in thickness, of white quartz with specks of ore. Where did that quartz come from? From the limestone? But the limestone contains very little silica, and is apparently of normal composition quite up to the vein. From the trap? This is compact, sonorous basalt, apparently unchanged; and that could not have supplied the silica without complete decomposition.
I should rather say from silica bearing hot waters that flowed up along the sides of the trap, depositing there, as in the numerous and varied veins of the vicinity, mineral matters brought from a zone of solution far below.
To summarize the conclusions reached in this discussion. I may repeat that the results of all recent as well as earlier observations has been to convince me that Richthofen’s theory of the filling of the Comstock lode is the true one, and that the example and demonstration of the formation of mineral veins furnished by the Steamboat Springs is not only satisfactory, but typical.
* * * * *
[NATURE.]
HABITS OF BURROWING CRAYFISHES IN THE UNITED STATES.
On May 13, 1883, I chanced to enter a meadow a few miles above Washington, on the Virginia side of the Potomac, at the head of a small stream emptying into the river. It was between two hills, at an elevation of 100 feet above the Potomac, and about a mile from the river. Here I saw many clayey mounds covering burrows scattered over the ground irregularly both upon the banks of the stream and in the adjacent meadow, even as far as ten yards from the bed of the brook. My curiosity was aroused, and I explored several of the holes, finding in each a good-sized crayfish, which Prof. Walter Faxon identified as _Cambarus diogenes_, Girard _(C. obesus_, Hagen), otherwise known as the burrowing crayfish. I afterward visited the locality several times, collecting specimens of the mounds and crayfishes, which are now in the United States National Museum, and making observations.
At that time of the year the stream was receding, and the meadow was beginning to dry. At a period not over a month previous, the meadows, at least as far from the stream as the burrows were found, had been covered with water. Those burrows near the stream were less than six inches deep, and there was a gradual increase in depth as the distance from the stream became greater. Moreover, the holes farthest from the stream were in nearly every case covered by a mound, while those nearer had either a very small chimney or none at all, and subsequent visits proved that at that time of year the mounds were just being constructed, for each time I revisited the place the mounds were more numerous.
[Illustration: Fig. 1 Section of Crayfish burrow]
The length, width, general direction of the burrows, and number of the openings were extremely variable, and the same is true of the mounds. Fig. 1 illustrates a typical burrow shown in section. Here the main burrow is very nearly perpendicular, there being but one oblique opening having a very small mound, and the main mound is somewhat wider than long. Occasionally the burrows are very tortuous, and there are often two or three extra openings, each sometimes covered by a mound. There is every conceivable shape and size in the chimneys, ranging from a mere ridge of mud, evidently the first foundation, to those with a breadth one-half the height. The typical mound is one which covers the perpendicular burrow in Fig. 1, its dimensions being six inches broad and four high. Two other forms are shown in Fig. 2. The burrows near the stream were seldom more than six inches deep, being nearly perpendicular, with an enlargement at the base, and always with at least one oblique opening. The mounds were usually of yellow clay, although in one place the ground was of fine gravel, and there the chimneys were of the same character. They were always circularly pyramidal in shape, the hole inside being very smooth, but the outside was formed of irregular nodules of clay hardened in the sun and lying just as they fell when dropped from the top of the mound. A small quantity of grass and leaves was mixed through the mound, but this was apparently accidental.
The size of the burrows varied from half an inch to two inches in diameter, being smooth for the entire distance, and nearly uniform in width. Where the burrow was far distant from the stream, the upper part was hard and dry. In the deeper holes I invariably found several enlargements at various points in the burrow. Some burrows were three feet deep, indeed they all go down to water, and, as the water in the ground lowers, the burrow is undoubtedly projected deeper. The diagonal openings never at that season of the year have perfect chimneys, and seldom more than a mere rim. In no case did I find any connection between two different burrows. In digging after the inhabitants I was seldom able to secure a specimen from the deeper burrows, for I found that the animal always retreated to the extreme end, and when it could go no farther would use its claws in defense. Both males and females have burrows, but they were never found together, each burrow having but a single individual. There is seldom more than a pint of water in each hole, and this is muddy and hardly suitable to sustain life.
[Illustration: Fig. 2 Crayfish Mound]
The neighboring brooks and springs were inhabited by another species of crayfish, _Cambaras bartonii_, but although especial search was made for the burrowing species, in no case was a single specimen found outside of the burrows. _C. bartonii_ was taken both in the swiftly running portions of the stream and in the shallow side pools, as well as in the springs at the head of small rivers. It would swim about in all directions, and was often found under stones and in little holes and crevices, none of which appeared to have been made for the purpose of retreat, but were accidental. The crayfishes would leave these little retreats whenever disturbed, and swim away down stream out of sight. They were often found some distance from the main stream under rocks that had been covered by the brook at a higher watermark; but although there was very little water under the rocks, and the stream had not covered them for at least two weeks, they showed no tendency to burrow. Nor have I ever found any burrows formed by the river species _Cumbarus affinis._ although I have searched over miles of marsh land on the Potomac for this purpose.
[Illustration: Fig. 2 Crayfish Mound (shorter)]
The brook near where my observations were made was fast decreasing in volume, and would probably continue to do so until in July its bed would be nearly dry. During the wet seasons the meadow is itself covered. Even in the banks of the stream, then under water, there were holes, but they all extended obliquely without exception, there being no perpendicular burrows and no mounds. The holes extended in about six inches, and there was never a perpendicular branch, nor even an enlargement at the end. I always found the inhabitant near the mouth, and by quickly cutting off the rear part of the hole could force him out, but unless forcibly driven out it would never leave the hole, not even when a stick was thrust in behind it. It was undoubtedly this species that Dr. Godman mentioned in his “Rambles of a Naturalist,” and which Dr. Abbott _(Am. Nal.,_ 1873, p. 81) refers to _C. bartonii_. Although I have no proof that this is so, I am inclined to believe that the burrowing crayfishes retire to the stream in winter and remain there until early spring, when they construct their burrows for the purpose of rearing their young and escaping the summer droughts. My reason for saying this is that I found one burrow which on my first visit was but six inches deep, and later had been projected to a depth at least twice as great, and the inhabitant was an old female.
I think that after the winter has passed, and while the marsh is still covered with water, impregnation takes place and burrows are immediately begun. I do not believe that the same burrow is occupied for more than one year, as it would probably fill up during the winter. At first it burrows diagonally, and as long as the mouth is covered with water is satisfied with this oblique hole. When the water recedes, leaving the opening uncovered, the burrow must be dug deeper, and the economy of a perpendicular burrow must immediately suggest itself. From that time the perpendicular direction is preserved with more or less regularity. Immediately after the perpendicular hole is begun, a shorter opening to the surface is needed for conveying the mud from the nest, and then the perpendicular opening is made. Mud from this, and also from the first part of the perpendicular burrow, is carried out of the diagonal opening and deposited on the edge. If a freshet occurs before this rim of mud has had a chance to harden, it is washed away, and no mound is formed over the oblique burrow.
After the vertical opening is made, as the hole is bored deeper, mud is deposited on the edge, and the deeper it is dug the higher the mound. I do not think that the chimney is a necessary part of the nest, but simply the result of digging. I carried away several mounds, and in a week revisited the place, and no attempt had been made to replace them; but in one case, where I had in addition partly destroyed the burrow by dropping mud into it, there was a simple half rim of mud around the edge, showing that the crayfish had been at work; and as the mud was dry the clearing must have been done soon after my departure. That the crayfish retreats as the water in the ground falls lower and lower is proved by the fact that at various intervals there are bottled-shaped cavities marking the end of the burrow at an earlier period. A few of those mounds farthest from the stream had their mouths closed by a pellet of mud. It is said that all are closed during the summer months.
How these animals can live for months in the muddy, impure water is to me a puzzle. They are very sluggish, possessing none of the quick motions of their allied _C. bartonii,_ for when taken out and placed either in water or on the ground, they move very slowly. The power of throwing off their claws when these are grasped is often exercised. About the middle of May the eggs hatch, and for a time the young cling to the mother, but I am unable to state how long they remain thus. After hatching they must grow rapidly, and soon the burrow will be too small for them to live in, and they must migrate. It would be interesting to know more about the habits of this peculiar species, about which so little has been written. An interesting point to settle would be how and where it gets its food. The burrow contains none, either animal or vegetable. Food must be procured at night, or when the sun is not shining brightly. In the spring and fall the green stalks of meadow grasses would furnish food, but when these become parched and dry they must either dig after and eat the roots, or search in the stream. I feel satisfied that they do not tunnel among the roots, for if they did so these burrows would be frequently met with. Little has as yet been published upon this subject, and that little covers only two spring months–April and May–and it would be interesting if those who have an opportunity to watch the species during other seasons, or who have observed them at any season of the year, would make known their results.
RALPH S. TARR
* * * * *
OUR SERVANTS, THE MICROBES.
Who of us has not, in a partially darkened room, seen the rays of the sun, as they entered through apertures or chinks in the shutters, exhibit their track by lighting up the infinitely small corpuscles contained in the air? Such corpuscles always exist, except in the atmosphere of lofty mountains, and they constitute the dust of the air. A microscopic examination of them is a matter of curiosity. Each flock is a true museum (Fig. 1), wherein we find grains of mineral substances associated with organic debris, and germs of living organisms, among which must be mentioned the _microbes_.
Since the splendid researches of Mr. Pasteur and his pupils on fermentation and contagious diseases, the question of microbes has become the order of the day.
In order to show our readers the importance of the study of the microbes, and the results that may be reached by following the scientific method created by Mr. Pasteur, it appears to us indispensable to give a summary of the history of these organisms. In the first place, what is a microbe? Although much employed, the word has not been well defined, and it would be easy to find several definitions of it. In its most general sense, the term microbe designates certain colorless algae belonging to the family Bacteriaceae, the principal forms of which are known under the name of _Micrococcus. Bacterium, Bacillus. Vibrio, /Spirillum, etc_.
In order to observe these different forms of Bacteriaceae it is only necessary to examine microscopically a drop of water in which organic matter has been macerated, when there will be seen _Micrococci_ (Fig. 2, I.)looking like spherical granules, _Bacteria_ in the form of very short rods, _Bacilli_ (Fig. 2, V.), _Vibriones_ (Fig. 2, IV.,) moving their straight or curved filaments, and _Spirilli_ (Fig. 2, VI.), rolled up spirally. These varied forms are not absolutely constant, for it often happens in the course of its existence that a species assumes different shapes, so that it is difficult to take the form of these algae as a basis for classifying them, when all the phases of their development have not been studied.
The Bacteriaceae are reproduced with amazing rapidity. If the temperature is proper, a limpid liquid such as chicken or veal broth will, in a few hours, become turbid and contain millions of these organisms. Multiplication is effected through fission, that is to say, each globule or filament, after elongating, divides into two segments, each of which increases in its turn, to again divide into two parts, and so on (Fig. 2, I. b). But multiplication in this way only takes place when the bacteria are placed in a proper nutritive liquid; and it ceases when the liquid becomes impoverished and the conditions of life become difficult. It is at this moment that the formation of _spores_ occurs–reproductive bodies that are destined to permit the algae to traverse, without perishing, those phases where life is impossible. The spores are small, brilliant bodies that form in the center or at the extremity of each articulation or globule of the bacterium (Fig. 2, II. l), and are set free through the breaking up of the joints. There are, therefore, two phases to be distinguished in the life of microbes–that of active life, during which they multiply with great rapidity, are most active, and cause sicknesses or fermentations, and that of retarded life, that is to say, the state, of resting spores in which the organisms are inactive and consequently harmless. It is curious to find that the resistance to the two causes of destruction is very different in the two cases.
In the state of active life the bacterides are killed by a temperature of from 70 to 80 degrees, while the spores require the application of a temperature of from 100 to 120 degrees to kill them. Oxygen of a high pressure, which is, as well known from Bert’s researches, a poison for living beings, kills many bacteria in the state of active life, but has no influence upon their spores.
In a state of active life the bacteriae are interesting to study. The absence of green matter prevents them from feeding upon mineral matter, and they are therefore obliged to subsist upon organic matter, just as do plants that are destitute of chlorophyl (such as fungi, broomrapes, etc.). This is why they are only met with in living beings or upon organic substances. The majority of these algae develop very well in the air, and then consume oxygen and exhale carbonic acid, like all living beings. If the supply of air be cut off, they resist asphyxia and take the oxygen that they require from the compounds that surround them. The result is a complete and rapid decomposition of the organic materials, or a fermentation. Finally, there are even certain species that die in the presence of free oxygen, and that can only live by protecting themselves from contact with this gas through a sort of jelly. These are ferments, such as _Bacillus amylobacter,_ or butyric ferment, and _B. septicus_, or ferment of the putrefaction of nitrogenized substances.
[Illustration: FIG. 1.–ATMOSPHERIC DUST.]
These properties explain the regular distribution of bacteria in liquids exposed to the air. Thus, in water in which plants have been macerated the surface of the liquid is occupied by _Bacillus subtilis_. which has need of free oxygen in order to live, while in the bulk of the liquid, in the vegetable tissues, we find other bacteria, notably _B. amylobacter_, which lives very well by consuming oxygen in a state of combination. Bacteria, then, can only live in organic matters, now in the presence and now in the absence of air.
What we have just said allows us to understand the process of cultivating these organisms. When it is desired to obtain these algae, we must take organic matters or infusions of such. These liquids or substances are heated to at least 120 deg. in order to kill the germs that they may contain, and this is called “sterilizing.” In this sterilized liquid are then sown the bacteria that it is desired to study, and by this means they can be obtained in a state of very great purity.
The Bacteriaceae are very numerous. Among them we must distinguish those that live in inert organic matters, alimentary substances, or debris of living beings, and which cause chemical decompositions called fermentations. Such are _Mycoderma aceti_, which converts the alcohol of fermented beverages into vinegar; _Micrococcus ureae_, which converts the urea of urine into carbonate of ammonia, and _Micrococcus nitrificans,_ which converts nitrogenized matters into intrates, etc. Some, that live upon food products, produce therein special coloring matters; such are the bacterium of blue milk, and _Micrococcus prodigiosus_ (Fig. 2, I.), a red alga that lives upon bread and forms those bloody spots that were formerly considered by the superstitious as the precursors of great calamities.
[Illustration: Fig. 2.–VARIOUS MICROBES. (Highly magnified.)]
Another group of bacteria has assumed considerable importance in pathology, and that is the one whose species inhabit the tissues of living animals, and cause more or less serious alterations therein, and often death. Most contagious diseases and epidemics are due to algae of this latter group. To cite only those whose origin is well known, we may mention the bacterium that causes charbon, the micrococcus of chicken cholera, and that of hog measles.
It will be seen from this sketch how important the study of these organisms is to man, since be must defend his body against their invasions or utilize them for bringing about useful chemical modifications in organic matters.
_Our Servants._–We scarcely know what services microbes may render us, yet the study of them, which has but recently been begun, has already shown, through the remarkable labors of Messrs. Pasteur, Schloesing and Muntz, Van Tieghem, Cohn, Koch, etc., the importance of these organisms in nature. All of us have seen wine when exposed to air gradually sour, and become converted into vinegar, and we know that in this case the surface of the liquid is covered with white pellicles called “mother of vinegar.” These pellicles are made up of myriads of globules of _Mycoderma aceti_. This mycoderm is the principal agent in the acidification of wine, and it is it that takes oxygen from the air and fixes it in the alcohol to convert it into vinegar. If the pellicle that forms becomes immersed in the liquid, the wine will cease to sour.
The vinegar manufacturers of Orleans did not suspect the role of the mother of vinegar in the production of this article when they were