# Popular Science Monthly/Volume 17/May 1880/Popular Miscellany

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POPULAR MISCELLANY.
Where to find the Crayfish.—Professor Huxley, in his valuable work on the cray-fish, published in the "International Scientific Series," tells his readers to study the work with "crayfish in hand." In order that readers may be able to do this, the following localities are given, copied from Dr. Hagen's monograph on the Astacidæ, with some localities added by the author: Vermont: in affluents of Lake Champlain; at Burlington, Shelburne, Colchester, Chittenden County. Massachusetts: Western parts of the State, on the authority of Mr. S. H. Scudder. New York: Hudson River and its affluents; Newburg, Fishkill; in the Tioga, affluent of the Susquehanna; at Berkshire, Tioga County; Lake Ontario; Genesee River, at Rochester; Garrison Creek, near Oswego; Lake Oneida; Four-Mile Creek, near Sackett's Harbor; and Grass River, a branch of the St. Lawrence; also at Niagara. New Jersey: Essex, Schooley's Mountain, Morris. Pennsylvania: in Delaware River (Philadelphia), Schuylkill River (Carlisle, Reading); Susquehanna and its affluents (Hummelstown, Berwick); Ohio River (Pittsburgh). Maryland: Havre de Grace. Virginia: James River and its affluents (Petersburg), the Rappahannock (Fredericksburg), and Greenbrier River. District of Columbia: Georgetown. North Carolina: Beaufort. South Carolina: Wateree River, Charleston, and Summerville. Georgia: Athens, Milledgeville, Roswell. Florida: Pensacola. Alabama: Huntsville, Mobile. Mississippi: Mobile River, Monticello, Rootpond. Louisiana: New Orleans, Millikin's Pond. Tennessee: Lebanon. Kentucky: Mammoth Cave, Little Hickman, Hickman's Landing. Indiana: Wabash River (Delphi). Ohio: Cincinnati, Columbia, Dayton, Miami River, Kelley Island, Lake Erie. Michigan: Lake Superior, and reported from Lake St. Clair. Wisconsin: Sugar River, and also reported from Milwaukee. Minnesota: Collected by Professor Agassiz at Minnehaha Falls. Iowa: Mississippi River at Davenport and Burlington. I have found it in greatest abundance at Dubuque. Illinois: Chicago, Evanston, Ogle County, Lawn Ridge, Basson Pudge, Peoria, Athens, Quincy, Belleville, Illinois River and its affluents. Missouri: St. Louis, and Osage River. Arkansas: One species reported, locality unknown. Texas: Between San Antonio and El Paso del Norte. Nebraska: One species reported, without locality. Washington Territory: Puget Sound. Oregon: Astoria, Columbia River, Lake Klamath. California: San Francisco. Canada: Humber River, near Toronto; Lake Winnipeg, Saskatchewan and Red Rivers. I have found them in the watercourses of northern Maine, and St. John's River, in New Brunswick. Dr. Hagen's monograph was published ten years ago. Many new localities have been recorded since; doubtless they will be found in every State and Territory in the Union. The animals may be found sheltered under or between loose stones along the edges of brooks and rivers. They are very active in their efforts to escape. Owing to their greenish and brownish hues, it is difficult to find them. They may easily be kept in confinement for a long time, and their movements and habits studied.—Edward S. Morse.
​The Winter in Europe.—The earlier part of the winter of 1879-'80, while it was exceptionally mild in America, was distinguished in Europe for its severity. In France it is spoken of as the coldest winter which has been recorded for more than a century. It appears that the temperature of October was a little below the usual mean. November gave twelve days of frost; and December surpassed everything that had been known in Paris, in the intensity and duration of the cold. From the 26th of November to the 28th of December, that is, during thirty-three consecutive days, there was frost every day, and during fourteen days of the period, from the 14th to the 28th of December, the thermometer did not rise above the freezing-point. The beginning of December was tempestuous. The storm-center, coming up from the ocean on the morning of the 3d, passed Paris between the 4th and 5th, accompanied by a rapid depression of the barometer and a perceptible rise of temperature from about 18°. The storm, having caused great damage in France, then went to the east, and gradually diminished in intensity as it passed over Germany. About ten inches of snow fell during this storm, and four inches more on the 8th, after which it cleared off, and the extraordinary cold began. The mean temperature of December in Paris is 3812°; the temperature of December, 1879, was 18·3°. The lowest mean temperatures previously recorded in the present century were in 1812 (30·2°), 1829 (25·7°), and 1840 (27·9°). The nearest approach to the temperature of the last December was probably in December, 1788, but the uncertainty of the observations taken at that period makes an exact comparison impracticable. The temperature on the 10th (-14°) was the lowest ever observed. The cold, at the period of its greatest intensity, on the 9th and 10th, presented a remarkable distribution over the surface of Europe. On the first day, two centers of cold were manifested, one being toward Poland, where the thermometer sunk to -32°, the other in the French departments east of Paris. On the second day, the former center had increased in surface but diminished in intensity, while the second center had extended and had reached Paris, and the cold had increased over nearly the whole of France. The temperature continued high on the borders of the British Channel and the ocean, so that great contrasts were presented in places not very far from each other according as they were near to or removed from the sea. Vegetation suffered from the duration of the cold, so that most of the exotics in the public gardens were killed or greatly injured. A zone of high pressure was established in all the west of Europe after the storm of the beginning of the month, the center of which oscillated from France to Poland and from Austria to Denmark. It was observed that the low temperature was special to the inferior regions of the atmosphere. At the height of a little over a thousand yards the air was much more mild. During the latter part of the month the thermometer on the Puy-de-Dôme was often thirty to forty degrees higher than at Clermont, and on the Pic du Midi it rose every day after the 19th to above the freezing-point, while it was still always below it at Paris. The cold terminated suddenly on the 28th, with a storm from the North Sea; a thaw followed, with destructive floods. A new cold term set in after the 4th of January, with a region of high pressure in the center of Europe. The summits again showed a higher temperature than the base of the mountains. The region of extreme cold was this time, however, in Russia.
M. Marié Davy, Director of the Observatory of Montsouris, remarks, in a communication to the Société Française d'Hygiène, that this has been the sixth severe winter of the century; and the six have recurred with remarkable regularity in periods of two each, viz.: 1788-'89 and 1794-'95, interval six years; 1829-'30 and 1837-38, interval eight years; 1871-'72 and 1879'80, interval eight years. These periods were each removed to a medium distance of about forty-two years from each other. The near equality of the periods of recurrence is probably a simple coincidence, but it is nevertheless curious. M. Faye has published an account of the meteorological observations, which have been made to the month of May, 1879, at the observatory of the French missionaries in China, at Zi-kawei. From them the director of the observatory draws the conclusions—1. That storms and tempests, and in general all barometric depressions, are propagated in ​China and Japan in the same course as the storms and tempests of the Atlantic which reach Europe; 2. That such storms are independent of the prevailing monsoon, and reciprocally, neither interfering with the other. Thus, says M. Faye, in regions opposed to ours in the northern hemisphere, the storms which we call cyclones or typhoons follow identically the same course, whatever may be the distribution of water and land, whether there are currents of warm water like the Gulf Stream, chains of mountains or not, on their way, whatever may be the direction of the lower winds prevailing in the country. The origin of these gyratory phenomena is, then, in the upper region of the atmosphere, whence, away above all the superficial accidents of the globe, they descend to the ground through the lower strata.
Wild Silks.—That our resources for the production of silk are capable of great enlargement is shown by the fact that heretofore only a few of the numerous insects which form silk and only a small number of the plants on which they feed have been utilized, leaving the greater number of insects and plants still unemployed. The known silk-spinners belong to the two families Bombycidæ and Saturniidæ, of the Lepidoptera. All of the Saturniidæ are silk-spinners, but not all of the Bombycidæ. Of the Saturniidæ, the British Museum catalogue contains the names of two hundred and ninety-four species, and one hundred more species have been added since the catalogue was published. Mr. Thomas Wardle, in a lecture on the wild silks of India, before the Society of Arts, gave a list of fifty-seven silkworms indigenous to India, of which six mulberry-feeding sorts are domesticated, and the others are wild. Besides the mulberry-feeding worms, of which there are also nine wild species, the cocoons of fourteen wild species are utilized. Of these, the principal species are the Attacus ricini, the Attacus cynthia, or Eria-worm, the Antheræa Assama, or Muga-worm, and the Antheræa paphia, or Tusser-worm. The Attacus ricini is a native of Assam, and feeds on the castor-oil plant and several other plants of the country. The cocoons can not be reeled, but the fiber is exceedingly well adapted for spinning, can be dyed and print ed easily and satisfactorily, and forms a cloth of "incredible durability, the life of one person being seldom sufficient to wear out a garment made of it, so that the same piece descends from mother to daughter." Attacus cynthia feeds on the ailantus, and has been successfully domesticated in France and England, where "ailanticulture" has a recognized place in industrial economy. Its silk is not adapted for reeling, but spins well, and there is no doubt, says Mr. Wardle, "that a great future remains for this silk, now that spinning-machinery has been so perfected." The Attacus Atlas is almost omnivorous, yields a "decidedly good" silk, and has been recommended for introduction into France. The Antheræa Assama yields the Muga silk, which forms one of the chief exports of Assam. Five thousand acres are planted in Assam and some Tipperah villages with food for the worm, and are capable of yielding 123,000 pounds of the fiber. Mr. Wardle reports of the silk that it bleaches well, and takes the dye freely, better than Tusser. The Antheræa paphia, from which the Tusser silk is derived, is the most widely distributed as well as the most important of the wild-silk producers of India, and has been utilized for many centuries. It feeds on a variety of plants, among them the castor-oil plant, and begins to spin its cocoons in six weeks from the time it is hatched. The silk is woven and used in the provinces of India in mixed fabrics of cotton woof and Tusser weft, but seems also to be used pure in many cloths. The fiber of this silk is flat, thereby showing a strong difference from that of the mulberry silk, which is round, and to this is ascribed its glassy look. So far from this property being a drawback, the luster seems to be enhanced by it after the fiber has become modified and its flatness has been diffused in the loom. The chief obstacle to the general introduction of this silk is the difficulty with which it is made to take colors. A process has been invented to overcome this by applying oxygen to the natural fawn-colored coloring matter of the fiber, but it is too expensive for general use. Mr. Wardle has found a partial solution of the difficulty in a more thorough cleansing of the native product and better reeling, and has made the silk submit to the dye and to the printing process in a tolerably ​satisfactory manner. In the undyed state it is the most lustrous of all silks, and is very strong. Some of the prints obtained by Mr. Wardle are beautifully suited to wall hangings, curtains, coverlets, and all kinds of furniture-work; and, while the material has not quite the brilliancy of the mulberry silk in its printed state, it has a richer and softer surface than those of cretonnes or challis, while its lasting qualities are superior to those of any other material. It is beginning to be largely used in France for fabrics and trimmings in which extreme fineness is not required.
Fertilization of the Algerian Sahara.—Some remarkable transformations in the character of the Algerian Sahara have been effected by irrigation. Under its operation a soil has been constituted, in which the intertropical plants grow with great vigor. A cultivator at Ouargla received several medals at the Parisian Exposition for plants which he had raised on a soil thus prepared. The stories that have been told of the productiveness of the Sahara tax the imagination. Fertility is not limited to any one point. It is exhibited wherever water has been brought to the surface of the soil. Most of the Saharan valleys and the beds of the subterranean streams have water in abundance, and only a small effort is needed to bring it to the surface. Sahara is not all a desert, but contains many considerable tracts which are already fit for cultivation. The success which has attended the efforts so far made to introduce tillage renders it nearly certain that a like reward may be gained from similar applications of labor in other parts. Henceforth it will be safe to say that the transformation of the Sahara is only a question of time, labor, artesian wells, means of communication, and security.
The Source of Marsh-Odors.—M. T. L. Phipson recently read, in the French Academy of Sciences, an account of the substances which he had succeeded in extracting from fresh-water algæ. They are palmelline, xanthophyll, chlorophyll, and characine. The last substance receives its name from the odor of chara, a well-defined marshy smell which it gives out. It is lighter than water, on the surface of which it forms minute pellicles, but is very sparingly dissolved. It is obtained by first drying the algae in the air, and then covering them again with cold water as in the preparation of palmelline. After eight or ten hours, a thin iridescent layer will appear on the surface of the water. This is the odorous substance in question. The liquid should be decanted into a long, narrow tube, and shaken with a quantity of ether. The ether dissolves the characine, and leaves it after evaporation in the form of a white, greasy, volatile substance, not saponifiable, soluble in alcohol and ether, hardly soluble in water, and having a strong characteristic odor of the marsh, which it communicates to the water. After some days it evaporates from the surface of the water, or disappears by oxidation, and the water loses its marshy odor. This odor, so strongly developed in plants of the genus Chara, is due to this new substance, which is formed by the plant itself during its life, and is not a product of decomposition. Characine is found in all the terrestrial algæ, and in the confervæ.
A Fossil Ferment.—M. Van Tieghem has called attention, in the French Academy of Sciences, to the evidence of the existence of the butyric ferment, bacilus amylobacter, in the coal period, which has been obtained by the microscopic examination of the radicles of conifers that have undergone its action, and are silicified in the phytogenic rocks of Saône-et-Loire. These fossils have been subjected to much study by M. B. Renault, assistant naturalist of the museum. The radicles exhibit precisely the same characteristic marks of alteration as are seen in corresponding radicles of the present epoch, which have been kept under water, and have become the prey of the bacilus. We know that the effect in the latter case is to subject the cellulose of the radicles to the butyric fermentation; and the conclusion is legitimate that the reactions developed in the marshes at the expense of the ligneous matter during the coal period were identical with those from which we observe the same effects now. The importance of these observations will be appreciated by those who are studying the part which causes that are now in operation have played in the geological past.
​Managing Horses by Electricity.—An ingenious and efficacious method of subduing savage or restive horses has been brought to the notice of the French Société d'Encouragement by M. Bella, administrator of the Omnibus Company of Paris. It is the invention of M. Defoy, who has illustrated its use by some remarkable exhibitions. The machinery is simple, and consists, as shown in the accompanying figure, of a Clark's magneto-electric apparatus inclosed in a box, which is placed within easy reach
of the driver or rider. A conducting wire running through the reins connects the apparatus with the bit. By turning a handle attached to the electro-magnet, a current is formed which affects the horse's mouth, and so surprises him that he stops and stands still. The most dangerous horse may be subdued in a short time by the application of the electric current, combined with a soothing manner and caresses. M. Bella ​has described experiments which M. Defoy tried with his apparatus upon some vicious and dangerous horses at the stables of the Omnibus Company. An Hungarian horse, which was considered unsafe to shoe, was brought up to the forge, making evident manifestations of his perversity. In a few minutes after the current was applied to him he allowed himself to be caressed on the shoulders and back, then let his legs be touched and his hind-feet raised; and, finally, suffered the workmen to change his shoes without being restrained or showing any further opposition to the proceedings. A trial of the apparatus was also made in the presence of the director of the Cab Company of Paris upon some horses which it had till then been impossible to shoe. They all yielded to its influence. One of them was accustomed to roll on the ground, strike out, and resist in every possible way. On the first application of the currents, says the director in his report, "To my astonishment they lifted his feet without any great difficulty; at the second, he was as easy to shoe as if he had never opposed the least resistance. The animal was conquered." M. Defoy exhibited before the editor of "La Nature" a dangerous horse, which he arrested instantly after it had sprung into a gallop, by turning the handle of the magneto-electric apparatus. The result is not obtained by any violent or painful action. The current is not strong enough to stupefy the animal; it rather produces in him astonishment, and a disagreeable but not painful sensation of an electrical pricking. The editor of "La Nature" has received the current from the apparatus without experiencing inconvenience. There is nothing in the process to recall the barbarous methods formerly used to subdue animals by force or violence, which hurt them in body and temper. M. Defoy has also invented an electrical stick or switch, which is not less ingenious than his bit. It is a riding-whip containing two conducting wires, which are insulated by leather. The wires terminate in two points set perpendicularly to the whip, and are put in connection, as in the case of the bit, by means of a magneto-electric apparatus. If the horse is in the habit of rearing, it is enough to jog him with the legs as he is preparing to rise, and at the same time apply the points of the electric stick to the top of his shoulders. He will immediately subside and let his head down. So, when a horse tries to turn around, the application of the current to that side of his face toward which he is about to turn will cause him to stop immediately. With the help of this little instrument M. Defoy is able in a little while to make a horse obey all his wishes.
Automatism in Portrait-painting.—Dr. Gaetan Delaunay, in a recent article on this subject, writes that he has often observed that a designer making an extemporaneous sketch of a head involuntarily reproduces his own portrait; and that, having made a scientific study of the fact, he has reached conclusions which are curious, though they are not fully demonstrated. He has been informed by teachers of drawing, painters, and designers, of whom he has made inquiries, that a person tracing with a pencil figures of spontaneous conception will always produce the same head unless he is copying from or imitating a model. M. Luys, professor in the Medical Faculty at Paris, states substantially the same principle in his work on the brain, and explains it by a theory of automatism, or habit. It is illustrated in the works of the French caricaturists. A degree of resemblance may be traced between the design and the designer, whether we consider the work as a whole or in its parts. English painters, endeavoring to represent Frenchmen, give them English characteristics, and French painters invest their figures of foreigners with a French air. So painters of every country impart some of their own national features to their pictures of foreign life, to such a degree that we can generally recognize the nationality of the artist from them. We can not explain the fact better than by supposing that all painters are subject to an irresistible tendency to reproduce their own ethnographic type. Sex exercises a similar influence; little girls amusing themselves at drawing will generally be found making female figures, little boys male figures. Dr. Delaunay has also observed that an artist seeking to represent a woman would always draw the same woman, and has learned from designers that the woman who thus persistently came from their pencil was, of the type which they preferred to all others, the one who figured in their dreams. Rubens is quoted as ​saying, "I paint women as I love them." Further, artists appear to embody their constitutional features in their figures, and will design large or small subjects according as they are themselves large or small. The figures of portly and vigorous artists will be distinguished by fullness of muscular development. According to this theory, the resemblance extends even to the different parts of the body. Raphael, who preferred to paint Virgins, had a virginal head; Michael Angelo, who had a virile head, put more virility into his creations. If we should go into the room where a deliberative body had sat, and gather up the figures which the members had amused themselves with composing during the tedium of discussion, we would be surprised by observing that each one had sketched something very like his own likeness. Dr. Delaunay has experimented with artists, and with persons who did not know how to draw, and has always found that they made their own profiles in their off-hand sketches. The sketch of an unpracticed person would of course be rude and ungraceful, and an unfair portrait, but there would be traits of resemblance about it sufficient to reveal the author. A friend who had what is called a square head drew a figure which was imperfect enough, but the line defining the back part of the head made a right angle. A person with curled hair is not apt to draw straight hair, but curled; one with straight hair will give his figures hair like his own; a bearded man will give them a full beard, a beardless man none; and peculiarities in the form of the beard are often found reproduced in the drawings. Finally, in the works of imagination of painters and sculptors we may recognize the productions of artists who have all the time multiplied their likenesses in their figures. The same conclusion is applicable to imitative designs. If we have a drawing class of fifty pupils, having a respectable degree of skill, all drawing at the same head, theoretically we should have fifty heads more or less well executed, but all resembling the model, and consequently one another. This will not, however, be the case. The drawings will differ from each other so obviously that, instead of fifty copies of the same head, there will be fifty different heads. Each pupil executes a different head from the one drawn by his neighbor, and more or less resembling his own head. In proof of this, a letter is quoted from a professor of drawing in a lyceum in Paris, who says: "When our pupils are competing for a prize, they have the same model in view, but each one in copying from it reproduces himself more or less. We may, by simply examining his design, determine whether his face is round, oval, or square, whether it has projecting forms, or a smooth contour with few inequalities." The same is the case with sculptors, and even with costumers, who were found by Dr. Delaunay to be most apt to have figures of their own style in view in fitting their customers.
Echoes in Buildings.—Cords stretched in a kind of network near the ceiling have been recommended for destroying echoes in churches and public halls, and have been tried satisfactorily in St. Peter's Church, Geneva, and in the Assembly Hall of the city offices of Bordeaux, France. When metallic wires are used in the same manner, the resonance is greatly diminished, and is sometimes converted into a musical sound. A remarkable resonance has been noticed in connection with the great staircase of stone in the Walhalla at Regensburg, Germany. The visitor, after going up the first stairs, steps upon a landing from which two other staircases rise in opposite directions. At this point every step calls out a metallic ringing, as if the whole stairs were made of brass. A stamp of the foot on the middle of the landing is answered by a clear, resounding, musical tone. The ringing continues as the visitor goes up the stairs, growing weaker as he approaches the second landing, and finally ceases. The phenomenon is believed to be due to the rapid reflections of the sound-waves between the opposite staircases.
Stammering of the Vocal Cords.—Under this title Dr. Prosser James, of London, describes in the "Lancet" a throat malady, which he says may at times entirely suspend the work of clergymen, lawyers, singers, and others who make professional use of the voice. The disease appears to be due to defective coördination of certain muscles of the larynx, in consequence of which the vocal apparatus fails at intervals to fully ​obey the will; the failure giving rise to sudden interruptions of the voice, while the articulating power may remain unaffected. As in other impediments of speech the harmonious action of the muscles engaged in articulation may be disturbed, in this case the disordered coordination affects the voice only. The movements required for articulating syllables are perfectly performed, but the production of vocal sound is at intervals suspended. The affection may cause the patient to stop speaking, as he is conscious of what he sometimes calls a "catch in the breath"; or he may continue a sentence from which some words will be lost to the listener. Isolated sounds are usually correctly articulated, even by confirmed stammerers; and the same is true in these vocal impediments; but it is in the rapid emission of certain combinations of sounds that the sudden arrest is liable to occur. Dr. James states that after long and patient observation of the action of the vocal cords, aided by appliances specially devised for the purpose, he was able to obtain ocular demonstration of the presence of the affection; and, once distinguished from other impediments of speech, he found it amenable to treatment.
Stature of the Japanese.—Mrs. Chaplin Ayrton, M. D., has recently published the results of nearly three hundred observations of the height and span of the Japanese. She found the average height to be five feet three inches, and the span four feet eleven inches. In the case of twenty-four women, taken at random, the tallest was a trifle over five feet two inches, and the average was four feet eight inches, with an average span of four feet six inches. The shortness of the span as compared with the height is a general characteristic that is especially marked in the case of the women. Sixty per cent, of the persons measured had the span less than the height, and thirty-three per cent, greater than the height, while in only 6·8 per cent, were the height and span equal. Climate can hardly be made to account satisfactorily for the smallness of the Japanese, for they live in a temperate region, though it is subject to sudden and marked changes. The general use of charcoal-braziers for heating may have something to do with it, by causing them to inhale the carbonic oxides. The characteristic of their food is the rarity of meat and the abundance of salt. Many of the additional causes of the smallness of the Japanese may be so remote as to cease to affect the nation except by hereditary influence.
Aids to Hearing: the Osteophone.—The audiphone and dentaphone, which have been extensively advertised as instruments for aiding the hearing of the deaf, have been objected to on account of mechanical difficulties in using them. The audiphone to a certain extent obscures the features of the person using it the dentaphone is held more or less in the line of vision; and both instruments require the constant service of the hands when in use. Dr. Charles II. Thomas, of Philadelphia, has devised an instrument that is intended to obviate these difficulties, which he has named the osteophone. It consists of a large receiving diaphragm attached in an arched form to a rod of wood or metal, which rod is bent in the form of a pipe-stem. One end of the rod is to be held firmly between the teeth as a pipe is held, leaving the hands of the listener free for other occupations, while he is able to hear all the sounds that may be conveyed by the diaphragm. The diaphragm is below and away from the face, and comparatively inconspicuous. The inventor suggests that ornamental fans, coated with shellac and tipped with ivory or hard rubber, may be made to answer fairly well for occasional use, but will be unsatisfactory if depended on permanently. Fuller's cardboard, treated with shellac varnish, and dried, makes one of the best of resounding mediums. A piece of yellow pine turned into a trumpet-shape, and placed in the mouth of the deaf person, will convey a good volume of sound, and even a string connecting the upper teeth of the persons conversing perceptibly aids the sound. A small rod of hard wood, connecting the teeth of the two persons, gives a volume of sound many times exceeding that transmitted either by the audiphone or the dentaphone. Sensible vibrations, produced by and corresponding to those of the voice, are propagated in the hard palate and base of the skull of persons speaking in the ordinary tones; and the rod ​which has just been mentioned will convey the voice distinctly when placed against the skull of the hearer, and will even, according to Dr. Thomas, convey audible speech from the skull of one to that of the other. The efforts to make the audiphone and denta-phone useful as regular instruments of hearing to the deaf have not had satisfactory results. Dr. Thomas acknowledges that the expectations which have been excited on the subject are likely to be disappointed. Those who are able to hear with the aid of the audiphone hear their own voices perfectly without it; while those who are unable to hear their own voices without it can hear nothing with it. Dr. Charles S. Turnbull, of Philadelphia, states in the "Medical and Surgical Reporter" that his experience with these instruments has been as nothing, because the suitable cases were so few and far between. The cases in which they have proved of benefit are cases of acoustic deafness, generally due to middle-ear disease, for which devices of the nature of the ear-trumpet generally afford a more satisfactory remedy than either of the instruments under consideration.
Deterioration of Bookbinding by Illuminating Gas.—Professor William Ripley Nichols publishes an interesting paper on the deterioration of the binding of books in libraries, which is commonly ascribed to the action of sulphuric acid supposed to be generated by burning coal-gas. The agency of sulphuric acid having been disputed by Dr. Wolcott Gibbs and others, Professor Nichols made investigations to determine the question. Having examined a large number of samples of leather in every stage of decay, he found that morocco was but little affected, common sheep binding was attacked, and Russia leather and calf were badly acted upon. An acid taste and an acid reaction were observed that were more marked in proportion as the leather was decayed, and sulphuric acid was found in the extract made from the leather with water, in a similarly increasing proportion. Ammonia was also present, in about such a proportion as in combination with the sulphur would constitute the acid sulphate of ammonia. Samples of fresh leather gave extracts only slightly acid, not enough so to affect the taste, and contained only a minute amount of sulphuric acid in combination. Samples of Russia leather and sheep of good quality yielded from less than a quarter to less than a half of one per cent, of acid, and less than quarter of one per cent, of ammonia. A sample of well-worn but not decayed sheep taken from a Bible more than sixty years old, which had never been exposed to gas, gave 1·42 per cent, of sulphuric acid. Other samples, of very rotten Russia, and of scrapings from a number of books, gave from eight to ten per cent, of sulphuric acid, combined with ammonia. A quantity of rotten leather was carefully extracted with water, and crystals of sulphate of ammonia were obtained from it. It is difficult, in the face of these facts, Professor Nichols urges, to escape the conviction that bindings of Russia, calf, or sheep absorb sulphuric acid when exposed to the products of the combustion of illuminating gas. No other condition to which books are commonly exposed can so well account for the large proportion of acid which was found in the old bindings. It has been objected to this view that sulphurous (not sulphuric) acid is the general product of the combustion of sulphur compounds; but Professor Nichols's analyses of the results of the burning of gas have brought out sulphates with no evidence of the presence of a sulphite. It is admitted to be possible that the disintegration of the leather precedes the absorption of sulphuric acid, and prepares the way for it; and Professor Nichols intends to make experiments for the determination of this question.