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notwithstanding they require several days' preparation in the lathe, owing to their hardness, yet, under a compression load of 100 tons per square inch, shorten .25 inch, and the harder kind (manganese, 15 to 20 per cent) .1 inch to .13 inch. Chilled iron or hardened steel would stand this test without any alteration. A cast specimen, No. 24 B (manganese, 14.75 per cent), not forged, made into a standard Whitworth test-piece, took nearly a fortnight to tool and finish.

The test-bar of the specimen (12.75 per cent) tested by Mr. Wellman, of the Otis Iron and Steel Company, Cleveland, O., was a day and a half in the lathe, as against half an hour for ordinary mild steel.

Owing to this peculiar hardness, its general application to castings has been limited by the difficulty of machining them, no method having yet been perfected by which the heads or runners can be cut off, or the castings otherwise tooled to shape. Tool steels from the best makers have been tried, including self-hardening kinds and tools made of manganese steel, but without success. The tests and applications, therefore, have necessarily been confined to castings, where the runners could be broken off cold or pared off hot.

Water-Quenching, and the Effect of Heat upon Manganese Steel.

Naturally one of the questions asked, when examining a new material said to be steel, or possessing the properties of steel, is, 'What effect has water or other cooling medium on it when plunged therein in a heated condition; in other words, will it harden?' Again: the behavior was found to be quite different when compared with ordinary carbon steel, no hardening action taking place. Water certainly causes the material to become stiffer, but in an entirely different degree to hardened carbon steel; for a piece of manganese steel, after such treatment, is slightly more easily touched by a file: therefore, for the following reasons, the process now described is termed 'water-toughening.' The increase in stiffness is most marked, the tensile strength rising from 40 to 60, and in some cases over 70, tons per square inch; but this is not a mere stiffening or hardening effect in the ordinary sense of the term, for in all carbon steel such rise is invariably accompanied, when the cooling medium is water, by a considerable decrease in the ductility or elongation, whereas in this material just the opposite effect is produced. In specimens Nos. 22 B and D2 the tensile strength of the bar as received from the forge was only 36 tons per square inch, with 1.56 per cent elongation. This latter is exceptionally low, usually being 6 to 8 per cent. After water-toughening, it rose to the extraordinary amount of 67 tons, with 44.44 per cent elongation; and even then the specimen was not fractured, as at this point it was considered worthy of being retained unbroken. The same result occurs if the piece under treatment be dipped when at a welding heat, though the carbon be as high as I per cent or more. With regard to those samples containing below about 7 per cent manganese, this treatment seems to exercise little or no influence, and the material is comparatively valueless where toughness is requisite. While touching upon this point, the results obtained by the Terre Noire Company of France with high manganese steel (1.75 to 2.25 per cent) should be referred to. It is stated that it was not possible to obtain test-bars when dipped in water or oil, as they either cracked or broke into pieces. Strange to say, not a single bar in these experiments has behaved so. Take, for example, No. 4 B, with 6.95 per cent of manganese, which may be termed comparatively low, and more approaching to the Terre Noire material: the test-bar, when heated to a white heat, could be safely plunged into either water or oil without being water-cracked.

After a large number of tests with regard to the action of heat and sudden cooling upon this material, generally speaking, it has been found that the higher the heat of the piece treated, and the more sudden and rapid the cooling, the higher will be the breaking load, and the greater the toughness or elongation. Six of the bars were heated as uniformly as possible to a yellow heat, and plunged into water of 72° F. These gave breaking loads varying from 57 to 63 tons per square inch, and elongations of 39.8 per cent to 50 per cent. As a comparative test, another test-bar of the same material, heated in precisely the same way and to the same de

gree, but plunged into water at a temperature of 202° F., gave only 53 tons and 32.8 per cent. The more rapid cooling of the other test-bars was evidently the cause of their superiority, the chemical composition of all being the same.

It was also thought that sulphuric acid, being a rapid conductor of heat, might give good results as a cooling medium. The experiment was therefore made with a bath consisting of equal volumes of water and of sulphuric acid, and on 8 inches the extraordinary elongation of 50.7 per cent was reached with a breaking load of 65 tons, the bar being thus drawn cold 4 inches before fracture. Another specimen on a 4-inch length gave 56.75 per cent. The operation of merely heating the forged test-bar to a yellow heat and cooling it in air has a very beneficial effect, the elongation in most instances being increased to 15 and 20 per cent, the tensile strength also rising 8 or 10 tons per square inch.

As before pointed out, the temperature to which the bar is subjected has a marked influence. Although good tests result when the specimens are treated at lower temperatures, the best are obtained with as high a temperature as possible, the bars being thoroughly soaked, and plunged into cold water. Care, of course, must be taken that they are not burnt, or heated beyond a welding heat. In those specimens where the alloy is not so pure a mixture of iron and manganese, and the material cannot be heated so hot without crumbling, lower temperatures also give good results, viz., 40 to 46 per cent elongation. The best tests have been obtained with material containing 12 to 14 per cent of manganese, though those with 10.83 per cent are also good, considering their high breaking loads as compared with mild steel. However, special attention is drawn to the peculiar fact that an increase of 4 per cent in the manganese causes such a considerable rise, both in tenacity and elongation. The cause of this is very obscure, the only explanation offered being that the peculiar crystallization in the cast ingots seems to disappear gradually after passing about II per cent, and the fibre noticed is not so much a cause of weakness. This is only surmise, as to the eye the fibre in even the lower percentages entirely disappears in the hammered bar.

It is not easy to understand the action of the water-quenching process. As so ably explained by Chernoff, the effect of oil-tempering on ordinary steel is to produce a metal of fine grain, which possesses much greater strength than open, coarse-grained steel. If, however, forged manganese steel possesses any real difference of structure, after being heated and water-toughened, it is rather in the direction of a more open than a closer grain. But the most puzzling case in the author's experience is that of the cast-toughened 9-per-cent specimens, at which percentage, as before pointed out, the crystallization is very peculiar. An ingot 2 inches square and 2 feet long was cast in an iron mould. When cold, a piece was broken off, requiring four blows under a steam-hammer. The fracture showed the usual peculiar form of the 9-per-cent material, a form which, to outward appearance, is unchanged by any heats short of the actual melting-point. The other piece was reheated to a yellow heat, and water-quenched. In this the toughness was increased in a remarkable manner, ten blows of the steam-hammer being required to break the bar. The appearance of fracture was unchanged. What caused the increase of toughness? In this case, certainly, it was not owing to structural changes, the pronounced form of ingot not being to the eye in any way altered. It will therefore be understood how difficult it is to offer any satisfactory explanation of these peculiarities.

Considering the effects of water-toughening, special attention is drawn to a specimen containing, carbon, 1.85 per cent ; manganese, 9.42 per cent. Ordinary steel with this amount of carbon would be excessively hard if water-quenched even at a dull-red heat; in fact, it is questionable whether it could be hardened at all without being water-cracked. Yet the above specimen was heated to a high heat, plunged into cold water, and the bar was not water-cracked, and, if changed at all, slightly softer. Carbon seems, therefore, entirely deprived of its usual hardening properties, and it is probable that manganese must be partly considered as the cause of the high tensile strength of this material, that is, unless iron itself possesses the property of taking some other form not hitherto suspected. Further, iron so combined with manganese is rendered capable of elongating 50 per cent on 8 inches, against about 30 per cent in

the best brands of wrought iron, which contain about 99.5 per cent of iron, against 84 per cent in the manganese steel.

Electrical Properties.

This material possesses the peculiar property of being almost entirely non-magnetic. Rinman mentioned in 1773 that manganese diminishes, and in the end destroys, the magnetic properties of iron. This was also noticed in some specimens of manganese alloys made by Mr. David Mushet about 1830. This is especially curious, seeing that iron is present in amounts eight or nine times greater than the manganese itself. An approximate idea of the amount of manganese contained in the steel may be formed by passing a magnet over specimens. As the percentage of manganese increases, the magnet's power decreases. Upon reaching about 8 per cent, there is no attraction in the bulk, though fine drillings are influenced; but even this diminishes, as, when 20 per cent is reached, a magnet capable of lifting 30 pounds of ordinary steel or iron will only lift pieces weighing a few milligrams. On this point the material behaves in the same manner either in its forged or cast state, water or oil quenching making practically no difference. Some interesting experiments with regard to the physical properties of manganese steel have been made by Sir William Thomson, Mr. Bottomley of Glasgow, and Professor Reinold of the Royal Naval College, Greenwich. Prof. W. F. Barrett, of the Royal College of Science, Dublin, has also experimented respecting its nonmagnetic character and electrical properties. His experiments were carried out upon a sample containing, carbon, .85 per cent; manganese, 13.75 per cent; the wire being drawn to No. 19 British wire gauge. The author first attempted to draw direct from the rods, but with little progress; the wire, owing to its hardness, breaking into short lengths when being pulled through the wortles. Ordinary annealing was tried, but with no better results. As exceedingly good bending tests have been obtained with bars from the same steel, when heated to a yellow heat and plunged into cold water, the rods were treated in the same manner. These were coiled up, heated to whiteness, and plunged into cold water. The material was then easily drawn; but, after every reduction through two sizes, its ductility was again lost, and the operation of heating to whiteness and quenching in cold water was again necessary. A specimen has been subjected to white heat no less than five times, and is yet uninjured, as will be seen from the remarkable tensile tests obtained from it by Professor Barrett, viz., 110 tons per square inch, in its hard state. A similar result was obtained by the manager of the wire department at the Barrow Steel Works, the report being "that it would stand any tensile load up to 100 tons per square inch, according to the temper, and the elongation was extraordinary." The density, according to Professor Barrett, was 7.81, which is somewhat lower compared with the specific gravity obtained at the Hecla laboratory; viz., 7.83 on the same wire. The electric conductivity was found to be very low; No. 19 British wire gauge wire, .96 millimetre in diameter, having a resistance of 1.112 legal ohms per metre, or 75 microhms per cubic centimetre at 15° C. Ordinary iron wire is only 9,800, and German-silver 21,170; so that use might be made of the manganese steel for resistance-coils in electric-lighting. This has since been successfully applied by Dr. E. Hopkinson, in Messrs. Mather & Platt's electric department. Its high specific resistance, and capacity to stand heating, make it very useful for resistance-boxes. A length of 1,180 yards No. 8 British wire gauge (No. 634, manganese 13.95 per cent) was cut into three lengths, coupled parallel, the conductor consisting of three strands No. 8, then coiled into a box 3 feet by 2 feet by 2 feet, and gave a resistance of 6.5 ohms, carrying 80 ampères without over-heating. It was therefore capable of absorbing 55-horse power. To produce the same resistance with iron wire, 5,000 to 8,000 yards would be required, or, of expensive German-silver wire, 4.780 yards. Professor Barrett also finds that its increase when heated is only .136 per cent for each degree carbon, as against iron .5 per cent.

In the same way it is a bad conductor of heat. A rough test was made at the Hecla works by putting a bar of this material and one of ordinary wrought iron into a smith's fire. The latter became too hot to handle in about half the time required for the former. From this will be seen the importance of thoroughly 'soaking' this steel when forging it, or the outside only may be heated.

As regards its non-magnetic properties, a small piece of the No. 552 wire was not attracted in the slightest degree by the most powerful electro-magnet capable of lifting a ton; but, suspended by a thread, it behaved like a paramagnetic body. Professor Reinold found that the water-quenched or softened wire acquired slightly more permanent magnetism, but that with both a most sensitive galvanometer-needle was required to show that the material was not copper or other non-magnetic body. The exact amount was determined by Professor Barrett after most careful experiments. In comparing this with ordinary steel, he states that it was like weighing hundredweights and grains on the same balance. The magnetism of ordinary iron being represented by the figure 100,000, manganese steel is 20, and its susceptibility, i.e., the induced magnetization, is about as low as zinc or other non-magnetic metal. It is somewhat extraordinary to find no sensible attraction exerted on this steel by the most powerful magnetic field that could be obtained, this agreeing with Dr. Hopkinson's experiments. If other difficulties can be overcome, this peculiar quality should make it suitable for dynamo bed-plates. Ships built of such steel would have no sensible deviation of the compass. Magnetic influence, while not affecting this material, passes through it, so that a needle placed upon a flat sheet of manganese steel can be readily moved by a magnet placed underneath. The same thing occurs if brass or sheet copper be substituted, but not with ordinary steel or iron. Further interesting experiments have also been lately made (September, 1887) by Profs. J. A. Ewing and William Low. The former concludes his experiments by stating, that, even under magnetic forces extending to 10,000 C.G.S. units, the resistance which this manganese steel offers to being magnetized suffers no change in any way comparable to that which occurs in wrought iron, cast iron, or ordinary steel, at a very early stage in the magnetizing proOn the contrary, the permeability is approximately constant under large and small forces, and may be therefore concluded as being only fractionally greater than that of copper, brass, or air.

cess.

MUSICAL BOXES.

MUSIC, both as a science and an art, has reached a stage of development so far advanced that further improvement in any department must necessarily seem slow and insignificant. Yet improvements are being made in many directions, seemingly small, but really great enough to demand more than a passing notice. A good instrument is, of course, necessary to the production of

FIG. 1.

good music; but upon even the best of such instruments as the violin or piano, for instance, good music cannot be produced without the aid of a good musician. Of musicians, as musicians go, there are plenty, — ordinary every-day musicians, not born to the art, but bred to the business, working at music as a trade, not as an art; but of good musicians, with a heritage of genius supplemented by a lifetime of labor spent in study, there are few.

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Most people are lovers of good music, or at least of melodious and harmonious sounds. Among these are many who are not musicians themselves, and by whom the services of a good musician are not at all times procurable, nor perhaps desirable. There is but one among the innumerable instruments in vogue to-day to which such persons can turn, an instrument in which more or less successful attempts have been made to combine not only the parts to be played upon, perfect of their kind, but also as close an approximation to the executive talents of a musician as mechanical skill will give. This instrument is known as the musical box, not the crude mechanism of a few decades ago, but the improved instrument of to-day.

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trade in musical boxes, but a visit to the establishment of M. J. Paillard will convince the most sceptical that automatic musical in

FIG. 6.

struments play an important part in satisfying the musical demands of the public.

MENTAL SCIENCE.

The Illusions of Drawing and Painting.1

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THE arts of drawing and painting depend upon the possibility of presenting to the eye a result in two dimensions of space which it will readily transform into one of three dimensions. In this process there is a large element of illusion of conscious, designed illusion. The chief factor in this process is perspective. If the spectator take, whether in imagination or reality, the position of the artist when making the design, the image on his retina will be the same as that on the artist's retina, and the design will be recognized as the counterpart of the reality, provided the spectator knows in general the nature of the object represented. If the facsimile is to be more exact, color must be imitated, light and shade introduced, and the retinal effect copied with all the skill of eye and hand. In order to have an æsthetic effect, the picture must represent known objects: the interpretation of two-dimensional objects into three-dimensional must be rendered easy by the knowledge of the three-dimensional. The artist must not create entirely new forms: exceptions are apparent only, and prove the rule. The poetic monsters are either conventionalized, or unite incongruous but existing forms, half man and half beast. This is especially necessary when the object of the drawing is purely intellectual, to make clear something not easily expressed in words, such as designs for houses, mechanical constructions, and the like. Here a more or less exact knowledge of the type of object represented is needed. To the layman such designs have little meaning.

In artistic painting, however, it is not the most detailed and exact drawing that produces the best result. Photography excels all manual art in this, but its effect is of a lower order. The same can be said of those clever productions by which a bas-relief appears drawn in two dimensions, or the objects of a panorama to stand out in three. One admires the skill, but it is a curiosity rather than a piece of art. But the object of art is not servile imitation, not to give the spectator an absolute illusion, but to arouse certain feelings, certain thoughts; and those details must be chosen that bring to mind the appropriate sentiments.

The spectator of a painting never loses entirely the sense of viewing a painted surface: for (1) the drawing is strictly accurate only for one point of view; every change of position vitiates the perspective; (2) the phenomena of binocular vision prevent the illusion (the points of the canvas are seen at the real distance of the eye from the canvas, and not at the various distances required by the perspective; while, furthermore, the real object would form different images on the two retina, and the painting gives two nearly alike); (3) even in viewing objects monocularly, we get impressions of distance, for the eye constantly moves, while these changes are quite different in viewing a painting with one eye (the illusion of a painting is no doubt increased by regarding it monocularly through a hollow tube); (4) color and light can be imitated, but their mental effect is recognizably different from that of the real objects.

A picture placed in a horizontal position produces the illusion nearly as well as in a vertical position. If it be a marine view, the water does not seem vertical in the former case, though in the latter it seems horizontal. If it be an architectural design, it is not displaced, any more than we confuse directions when we gaze at 1 By M. J. L. Soret, in Revue Scientifique, Nov. 3, 1888.

an object in a reclining position. This is the result of much practice in seeing the form of representations irrespective of their position, and in transforming the actual retinal image into the one that the artist intends. If you dispense with all light and shade, with all color, with all perspective, and leave simply a bare outline, then we can see in such an outline all the various designs which it can physically represent. If you draw one square within another and join the corners, you can see such a figure either as the description just given, or as the picture of a shallow trough looking into the bottom, or as a view of the same object from the bottom; and so on. Light and shade, familiarity with the design, decide what we shall see. This does not mean that the artist may neglect perspective, but only that the object of the perspective is to make easy the mental apperception of the spectator. Cases occur in which a painter violates the rules of perspective, if by following them he would produce a scientifically accurate but apparently unnatural result.

canvas.

In the perception of distance the objects touching the lower edge of the canvas are, as a rule, meant to be seen as in the plane of the This gives the spectator his point of view, while the framing of the picture by supplying a vertical and a horizontal, aids very materially his conception of position. If in a landscape we have the ground touching the lower end of the canvas, and the sky the upper, we can judge distances best. If a prominent object is cut at the edge of the canvas, it increases the difficulty of distance perception. Of course, the size of the painted objects need bear no approximation to the actual size. Our eye is trained to perceive form relations independently of size; and, if the real size of the object is familiar, we involuntarily suppose a more distant point of view. So, again, we generally underestimate the size of colossal figures, because we allow too much for our distance from them.

A more complete proof that imitation is not the artist's chief aim is that he attempts to represent motion in a single view, which physically is impossible. When a tree is represented in a wind, its branches are shown bent and strained in the direction of the wind; and this gives us at once the picture of a wind, of motion. So in a figure the attitude characteristic of a series of motions stands for the motion itself. It is not so much the fidelity as the suggestiveness of the attitude that is important. So, again, when objects move very rapidly, they become indistinct to our vision, and by painting them as indistinct the illusion of rapid motion is aided. If the motion is too rapid for the eye to follow, as in the rotation of the spokes of a carriage-wheel, the peculiar appearance can be imitated on canvas, and suggests extreme speed.

In the walk or run of an animal, although one position follows another with great rapidity, the eye selects certain positions as typical, and these the artist uses as the presentation of movement. Generally the position at the beginning or the end of a step is chosen. Instantaneous photography shows the great variety of positions in passing from one step to another; but many of these have an unnatural appearance to the eye, and the artist cannot utilize them.

A very distinctive illusion is shown in many portraits in which the eyes seem to follow the eyes of the spectator. This occurs when the model's eyes are facing the artist's. We assume the position of the artist, and so have the eyes in the picture looking at ours. If we move to one side, we get the illusion of the portrait's turning about, because the eyes still suggest direct vision, and the rest of the pose does not strongly contradict it. This lateral displacement, brought about by a change of position, is very slight in a painting, while very marked in a three-dimensional object. Paintings of animals frequently show similar effects. The true artist must understand and utilize such illusions, for they make the difference between what is lifelike and what is artificial.

THE HOMING INSTINCT. — Dr. George M. Gould (Progress, October, 1888) has collected authentic cases of animals finding their way homeward over long distances. Dogs, even when carried away in a blindfolded or drugged condition, find their way home over distances from five to five hundred miles; and in one case, when the dog was taken off along the two sides of a triangle, he came home by the third side. The exquisitely trained instinct of the flying pigeon, and similar capabilities of most animals, show the

great importance of this faculty. By way of explanation, Dr. Gould suggests, that, without the faculty of finding the way homeward, the sphere of an animal's life would be very narrow. The maintenance of the species would develop the power of seeking new fields and the power to turn homewards. The ordinary senses cannot account for this homing instinct, as actual experiments have shown. Dr. Gould sees here the true sixth sense, and regards it as a sensibility to changes in electric and magnetic tension, due to position on the earth's surface. The home is the animal's north pole. By habit, it is accustomed to the magnetic conditions there, but when away is restless, and finds its way homeward by this mysterious compass. Dr. Gould connects with this some fanciful speculations as to the import of the pineal gland as a possible magnetic organ, and some hints as to the physical nature of homesickness in mankind.

The

a report on any line that was a complete financial success. system in Brussels has not given perfect satisfaction, although improvements have been made that will reduce the cost. The road is on a small scale, however, and it does not necessarily follow that it would not pay, even now, if it was on a larger scale. The road, too, is a difficult one, with long grades of over three per cent. A careful study was made of the different types of accumulators in use at present, and an estimate is made of the comparative cost of storage-battery traction, as compared with that of horses. As a result, the commission advised that electric cars be tried, and states that it would be an honor to Milan, which was one of the first cities in the world to adopt electric-lighting on a large scale, to be also one of the first to utilize electricity for the propulsion of its

tramcars.

ELECTRICAL NEWS.

A Novel Telephone.

WE take the following from a recent issue of the New York Electrical Review: "The Lowth stettio-telephone hails from Chicago, and is a combined transmitter and receiver. A hollow extension about four inches long is attached to the receiver, from the end of which a small button protrudes slightly. The button is placed against the throat near the vocal chords, and the receiver is held against the ear in the usual manner. When the operator speaks, the vibrations of the throat are transmitted with, it is said, distinct clearness. The instrument is operated by the muscular vibrations that accompany the utterance of words. The inventor, James Lowth, is said to have been experimenting and working on this instrument for over ten years. When he first applied for a patent, three years ago, the authorities at Washington thought him a crank, and refused to issue one. He attached the instrument to wires in the office, and asked over it, What do you think now?' Back over the wire came, I give in. It works perfectly.' Our Chicago informant says it has been successfully operated between that city and Milwaukee, and in Pittsburgh it worked over a line seventy-five miles in length, on which were twenty-five Bell instruments." While, if the evidence is correct, this instrument certainly works, yet it is difficult to see how sounds produced by changing the relative positions of the tongue, teeth, and lips, such as go to make up a large part of the human voice, are accurately transmitted by this telephone. Never having seen one of these instruments, we do not yet "give in."

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FAURE'S NEW SECONDARY BATTERY. - In this battery M. Faure uses finely divided metals pressed together in a self-supporting mass, or metal plates are used having combined with them finely divided particles of the same metal. Each plate is surrounded by a sheet of prepared asbestos, the sheet being a thirty-second of an inch thick, dipped first into some soluble salt, and then into a solution of a soluble silicate capable of producing with the first an insoluble compound. In his cell M. Faure uses zinc combined with finely divided zinc, and copper combined with finely divided copper. The solution used is phosphate of potash. On subjecting such a cell to the action of the electric current, phosphate of copper is formed on the surface of the copper element. M. Faure then substitutes a fresh solution of phosphate of potash, and, upon discharging the battery, phosphoric acid is transferred from the solution to the zinc, and from the copper to the solution; so that the solution remains unchanged as regards its constituent elements. The preliminary preparation would be avoided if phosphate of copper were placed upon the copper element in the first instance; but phosphate of copper is not easy to obtain and manipulate, and the process described is said to accomplish the desired object.

AN ITALIAN COMMISSION ON ELECTRIC TRACTION. - The Società Anonima degli Omnibus of Milan some time ago selected three engineers to travel through Europe, inspect the various electric-traction roads in operation, and report on the adaptability to the tramways in Milan. The main part of the report of the experts is taken up with the description and discussion of storage-battery systems; overhead, underground, and rail conductor systems being only incidentally mentioned. The commission was unable to make

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coast of California, the central line passing near Punta Arenas. The space within the lines marked northern limit' and 'southern limit' indicates that in which the eclipse will be total. The duration of the eclipse will be about two minutes.

-During the past week the Society of Amateur Photographers of New York has been holding at its rooms, 122 West 36th Street, an informal exhibition of prints, the work of members of the society. The exhibition has proved very successful; so much so, that, at the request of many visitors, the exhibition will continue until Saturday, Dec. 15. About six hundred pictures are exhibited, and include views in many parts of Europe, China, Japan, Corea, the United States, historical buildings in this city, flash-light pictures, etc. The rooms will be open from 10 A.M. to 6 P.M., and from 7 to IO P.M. every day and evening this week, except Tuesday evening. There is no charge for admission, and non-members of the society wishing to see the exhibition can obtain tickets by writing to the secretary of the society.

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