PHOTOGRAPHING SEAWEEDS.

FIG. 49. and FIG. 50.

FIG. 51. and FIG. 52.

The slits must be made very exactly; above all, their edgesmust be absolutely sharp, every incorrectness being transferred to the picture. They may be made about one-third of a millimeter wide; if they are too narrow the picture will not turn out sharp. In making the slits it is a good plan to cut them in thin black paper, and to mount the latter on glass plates.

FIG. 53.

In a later description of the apparatus we learn that the discs containing the slits are often made circular in shape and so arranged that they can be revolved as shown in Fig. 53. This, of course, allows of a still greater variety of positions of the two apertures in relation to each other and an increasing number of grotesque effects. Reproductions of some of the pictures obtained are given.[3]See Figs. 48 to 52.

[3]Reprinted fromLa Science en Famille.

FIG. 54.—SEAWEED PHOTOGRAPH.

Of all the glorious creations of nature few are more beautiful than the delicate sea mosses to be found by the sea shore. Many delight in preserving them in a dry state, mounted on cards, but unfortunately they are usually so fragile that after a little while they fall to pieces. The photographer, however, is able to reproduce these beautiful formations and preserve them in a more permanent form bymeans of his camera. It is true that he cannot reproduce their delicate colorings, but the photographs can, if so desired, be lightly printed on platinum paper and colored as well as possible by hand.

Aspecialcamera is sold for making these little pictures.

FIG. 55.—STAMP CAMERA.

FIG. 56.STAMP PHOTO.

It contains a number of lenses all of the same focus. In front is an easel where the portrait is attached, surrounded by a suitable border. The images given are about the size of postage stamps (see Fig. 56), and when the negative is printed on a printing out or developing paper, toned or developed, they can be perforated and gummed at the back. They are very useful for sticking to letters, envelopes, and for business purposes.

There are several different ways of making these. Obtain some Balmain's luminous paint, and coat a piece of cardboard with it. Place this in the dark until it is no longer luminous; place this behind a glass transparency and expose to light, either daylight or, if at night-time, burn a small piece of magnesium wire. Return to the dark, remove the transparency, and aluminous photograph is obtained on the prepared card. A simple plan is to merely expose a piece of the prepared cardboard to the light and place it behind a transparency; then retire to a darkened room. The luminous paint, showing through it, will have a very pretty effect. If no glass transparency is at hand, a silver print can be used, if previously oiled and rendered translucent by vaseline or any other means.

Perhaps the beauties of nature are nowhere better exemplified than in flowers, and nothing can be prettier than photographs of them carefully arranged. When we say carefully arranged we mean, of course, artistically. The secret of arranging flowers—an art in itself—is to hide the fact that they have been arranged.

Among the best pictures of flowers which have appeared in print, are those by John Carpenter, an English gentleman, who has made this particular branch of photography his chief study, and has been awarded many prizes and medals for flower studies.

Some time ago we wrote to him asking for a few particulars of his method adopted, and he has been so very kind as to send the following valuable notes:

Suitable Flowers.—I find that the best colors to photograph are pale pink, yellow, white or variegated colors. Reds, browns, and dark colors generally, donotanswer well.

Flowers of irregular form are most suitable, such, for example, as chrysanthemums, lilies, poppies, etc. These give beautiful gradations of light and shade.

Grouping.—There is great scope here for artistic feeling. All appearance of formal arrangement must be avoided and a natural grouping should be aimed at. This becomes more difficult as the flowers must be somewhat on one plane to get them in proper focus. A round bunch of flowers which may appear very pretty to the eye would probably be utterly wrong to make a picture of.

Fannie Cassidy.FIG. 57.—A BOWL OF ROSES.

Lighting.—I have never worked in a studio, but have a small lean-to glass house in which I work. The top light is softened down by light shades so that the strongest light comes from the side. This gives solidity to the subject and is more pleasing than a flat lighting. Of course, the sun should never shine on the subject.

Plates and Exposure.—If colored flowers are being photographed, orthochromatic plates are a necessity, but for white flowers and light-green foliage ordinary plates may be employed. I generally use a medium isochromatic, stop the lens tof:22 and give exposure of from thirty to sixty seconds in summer and vary according to the season; sometimes twentyminutesis not too much.

Development.—My usual and favorite developer is pyro-ammonia, and in careful hands it cannot be beaten. I commence development with a minimum of pyro and work tentatively.

Using such a solution, for 2 ounces of developer I should commence with 1-1/2 grains pyro, 1 grain bromide, and 2 grains ammonia. If the image does not gain sufficient density add more pyro and bromide, but unless very fully exposed it is difficult to avoid too much density, especially if white flowers are being photographed.

I find a plain gray or dark background most useful, and to avoid flatness it may be set at an angle and not too near the subject.

Flowers should be photographed as soon as gathered, and if possible be placed in water. I have often found a plate spoiled by movement of the leaves or flowers, even with short exposures, although the movement was not perceptible to the eye. This is more especially the case in hot weather.

Take a portrait negative that is no longer of any use, and immerse it in a weak solution of hydrofluoric acid. The film will leave the glass. It is then washed and returned to the glass support. By stretching the film one way or the other, and allowing it to dry in this position, the most amusing prints can be made. Keep your fingers out of the acid!

A curious experiment showing that a photographic dry-plate can be otherwise affected than by light, so as to form an image upon it, is the following:

An image of copper in relief is necessary—a penny will do for this purpose. Place an unexposed dry-plate in a normal pyro developer, and on it lay the copper coin. After about five minutes or so, remove the penny, fix and wash the plate, when a perfect image of the penny will be found on it.

Similar experiments to that described above have been carried out by Prof. Fernando Sanford. He placed a coin on a dry-plate and connected it with the terminal of a small induction coil, capable of giving a spark of three or four millimeters, while a piece of tin foil upon the opposite side of the plate was connected with the other terminal of the coil.

Several negatives were made in this way, the accompanying photograph, Fig. 58, being from one of them. With one exception, they all show a fringe around them, due to the escape of the charge from the edge of the coin, which accounts for the formation of the dark ring observed around the breath figures made upon glass.

Later on he undertook to photograph in the same way objects insulated from the photographic plate, and has sincemade negatives of coins separated from the plate by paraffine, shellac, mica, and gutta percha. The accompanying photograph, Fig. 59, was made with the coin insulated from the photographic plate by a sheet of mica about 0.04 mm. thick. The mica was laid directly upon the film side of the plate, and the coin was placed upon it and connected to one terminal of the small induction coil already mentioned. A circular piece of tin foil of the circumference of the coin was placed upon the glass side of the plate directly opposite the coin, and was connected to the other terminal of the induction coil. The little condenser thus made was clamped between two boards, and was covered up in a dark room. Two small discharging knobs were also attached to the terminals of the induction coil, and were separated by a space of less than a millimeter, so that, when a single cell was connected with the primary coil, the spark between the knobs seemed continuous.

FIG. 58.

FIG. 59.

The plate was exposed to the action of the waves set up in this condenser for one hour, when it was taken out and the negative image developed upon it by the usual process.

These are reversed vignettes, that is to say, the margins round the portrait instead of being white as in the ordinary vignette are black. A method of making them was recently described by "Teinte" inThe Photogram. This was as follows:

Two methods can be adopted. The first of these about to be detailed, though entailing, perhaps, in the first place a trifle more trouble, produces the best results. We require a black background, preferably of black velveteen, large enough for a head and shoulders. As the material is not usually obtainable of a width greater than twenty inches or so, there will have to be a seam, and this must be very neatly done. The seamed velveteen is then stretched taut on a frame, which should preferably be covered first with calico, to prevent "sagging." Always, before use, dust the velveteen with a soft brush—say, a hat brush—to remove any adhering dust or fluff. Instead of velveteen, a good paper background can be used, only it must be seen that the surface is smooth and free from cracks or creases, and isdead black.

FIG. 60.—MAGIC VIGNETTER.

We require also a vignetting mask suitable to the subject, with a serrated edge. This has to be fixed inside the camera between the lens and plate.[4]The proper position can be found by trial; the further the card is away from the plate the softer and more gradual the vignetting. No special arrangement for holding this is required beyond what can be prepared by any one who can use his fingers. We take a piece of stout card,the outside of which will just fit into the folds of the camera's bellows, and by a little twisting it can be sprung in between the folds which will hold it. There is an opening in the center, square in shape, about quarter plate size. This acts as a frame to hold the vignetting mask, which has the opening of proper size and shape. By using a frame as described the vignetter can be moved about up and down and from side to side, and when the correct position is found fixed by drawing pins. The frame and vignetter should be blacked all over. For this purpose take some lampblack ground in turps, and mix with it a little gold size sufficient (found by trial) to prevent the lampblack from rubbing off when dry, but not enough to cause the paint to dry shiny.

[4]A vignetter for the purpose, as shown in Fig. 60, has been placed on the market.

A good distance to fix the vignetter is about one-third the extension of the camera when the object is in focus, measuring from the lens.

We adjust the camera so that the image of the figure falls in the correct position on the screen, and the vignette is made of such a size and shape as to give the amount required.

The shadow of the mask protects the edges of the plate surrounding the image, and in development we obtain a negative in which the image is vignetted into clear glass, and on printing from such the margins print dark. The printing of such a negative should be prolonged until the margins of the picture are quite lost, or they are apt to show after toning.

The sketch shows the arrangement of vignetter inside camera.

The other plan consists in making an ordinary negative, using preferably a dark background. From this is made a vignette in the ordinary manner. When this comes from the frame it is placed on a piece of clean glass—face up—and another piece of glass free from flaws placed over it. Now cut a piece of card to the size and shape of the vignetted portion of the print, and fix this with glue to a piece of cork. This piece of cork must vary in thickness with various pictures. Now place the cork on the glass so that the mask covers the picture and fix with glue to prevent slipping. Place thewhole out in diffused light, and allow the darkening of the margins to go on until sufficiently deep. The print is then toned.

The height of the card from the print must be such that no abrupt line is produced between the first printing and the darkened margin, but that one will shade into the other without break.

If we have an ordinary gelatine negative, say, of half-plate size, and require to enlarge it to a whole plate, the simplest plan is to thoroughly wash it and immerse in a solution composed of citric acid, 2 ounces; hydrofluoric acid, 1 ounce; acetic acid (glacial), 1 ounce; glycerine, 1/2 ounce; water, 20 ounces. The action of the hydrofluoric acid will be to detach the film from the glass, while the other acids will cause the film to spread out considerably; the action being even all over, the image is completely enlarged. It is then carefully removed and washed in plenty of clean water, after which it can be transferred to a larger piece of glass. The action is sometimes to weaken the negative in density; it is therefore occasionally necessary to intensify it.

Curious as it sounds, very good moonlight effects can be procured on a bright sunshiny day. A photograph is made of a landscape in dazzling sunlight, a small stop and rapid exposure being given. The plate should, if possible, be backed with any of the substances recommended to prevent halation. Choose a landscape, with the reflection of the sun's rays in water, and include this and the sun itself on the plate. It is best to wait, however, until the sun just disappears behind a cloud. Shade the lens so that the rays do not shine on it direct, and expose rapidly. Use an old or weak developer. The sun and its reflection will, of course, make their appearance first. Continue the development until the detail in the under-exposed parts is just visible, and fix. Print very darkly, and slightly over tone. If printing is done upon green developing paper, and a little re-touching with Chinese white, the effect is very good.

Photographed from Nature by Fred. Graf.FIG. 61.—MOONLIGHT PHOTOGRAPH.

There are few photographers who appear to be aware of the many beautiful phenomena of nature that can be studied by the aid of photography. Under the title of "Schnee Crystalle," Dr. G. Hellmann has published[5]a book on this subject profusely illustrated with engravings and photo-micrographic collotypes from direct photographs by Dr. R. Neuhaus.

[5]Rudolph Muckenberger, Berlin.

FIG. 62.—SNOW CRYSTALS. PHOTO BY DR. NEUHAUS.

Dr. Neuhaus describes his method of photographing snowflakes in Dr. Eder's Jarbuch, from which article we extract the most important and interesting paragraphs: Were we to attempt to photograph snow crystals in a perfectly cold room, the temperature is still higher than that out of doors; moisture at once precipitates upon the carrier of the object; the crystals would melt and evaporate after a short time. The work must be done in the open, and perfect success can be expected only when the temperature is near zero.

FIG. 63.—SNOW CRYSTALS. PHOTO BY DR. NEUHAUS.

Snow crystals evaporate rapidly even in low temperature, and the work requires to be done rapidly and with caution. Freshly fallen snow only will give a good photograph, and as we are compelled to work in the midst of the snow storm, the task becomes still more complicated and difficult. Snow crystals but a short time after falling break, the broken pieces freeze together and crystallization is destroyed. For the illumination of snow crystals, transmitted light only can be used; reflected light destroys the shadows, and injures the highlights, and the result is necessarily but a very imperfect picture of the object.

Photo by Martin.FIG. 64.—A NATURAL PHENOMENON IN ICE.

Diffused light, especially that of a dark winter's day, and during a snow storm, is not fit for this kind of photo-micrographic work, and we must resort to artificial light, preferably to that of a petroleum lamp. To prevent heat action emanating from the illuminating ray cone, an absorptive cell of alumsolution should be interposed. As alum solution freezes at about 20° Fahr., chloride of sodium is added. With Hartnark's projection system, at 31 mm. focus distance, from 5 to 7 seconds upon an erythrosine plate is ample.

FIG. 65.—PHOTOGRAPH OF FROST CRYSTALS.BY JAS. LEADBEATER.

Dr. Neuhaus has made photographs of more than 60 different ice and snow specimens. The pictures of ice crystals much resemble those of hoar frost, deposited after a cold winter's night. Of snow crystals, the doublets are highly interesting, two crystals merged into one, and those having passed througha moist stratum of air, when microscopic drops of water will freeze into the hexagonal form, giving the picture an appearance very much resembling cauliflower.

FIG. 66.—PHOTOGRAPH OF FROST.BY JAS. LEADBEATER.

The most difficult question of all remains, the cause of the various forms of the hexagonal crystals, which frequently change in the same snowfall. Instead of advancing a new hypothesis, says Hellmann, it is better to acknowledge that we know nothing positively in regard to this. In our knowledge of the form and structure of the snow we have made great advance since the time of Kepler, but after nearlyfour hundred years, we cannot give a satisfactory answer to his question, "Cur autem sexangula? Why six-sided?"

We do not know the special conditions which determine the formation of one or the other form of snow crystals. We have found that a low temperature favors the formation of tabular crystals; a higher temperature the star shaped crystals; these groups show such multifarious forms that it is necessary to seek for other causes which influence the formation of snow figures. There is offered here a broad field for new investigation and study.

We give a reproduction (Fig. 64) of a photograph of a curious group of crystals. Some water had been left in a 10×8 dish on a winter day, and a film of ice was seen floating on the surface. The formation of the crystals and the floral design were so beautiful that it was taken out and photographed. The delicate lace-like edging of the glacial tracery is the result of the deposition of hoar frost while draining off the water from the ice leaves and flowers and fixing the image in the camera.

Quite recently Mr. Jas. Leadbeater has favored us with some account of his beautiful work in this fascinating branch of photography, some samples of which are here given. He first makes his windows perfectly clear and waits for a keen frost. The camera is inside the room and a dark cloth-covered board is placed on the outside, leaning against a low balcony of wood. The exposure varies with the thickness of the crystals, from two to ten seconds, principally with a very small stop. Two reproductions of his pictures will be found on pp. 76-77.

The study of crystallization is undoubtedly an interesting and fascinating one, and photography may be made to play an important part in securing permanent records of these curious formations. If a drop of water containing a salt be allowed to drop upon a glass plate, it will, upon evaporation, deposite crystals of various kinds. In a recent article inLa Nature, by Dr. E. Trouessart, a description is given of thebeautiful crystallic forms deposited by a drop of ink on evaporation. The article is translated in theLiterary Digest, from which we make extracts:

"Take a sheet of glass, deposit on it a drop of ink and spread the drop a little, uniformly; let it dry for a few minutes; then examine with a microscope, magnifying from 50 to 200 diameters, and you will be able to see the flowers of ink in process of formation under your eyes; that is to say, regular white crystal particles which detach themselves from the black or violet medium, and arrange themselves so as to form regular figures.

"If you are pressed for time, this beautiful result will easily be obtained by passing the sheet of glass over a spirit lamp or a candle to evaporate the moisture. The crystals will then be smaller and more numerous, presenting the appearance of a dark firmament densely sprinkled with bright silvery stars. But if you have patience to wait for evaporation without heat, you will obtain larger crystals of more varied forms, arranging themselves as crosses, flowers, etc.

"These crystals may be varied indefinitely by modifying the compositions of evaporation, adding more ink, etc. But it is quite possible that different inks will give different results. The inks I use, like all the other inks in use, have a basis of sulphate of iron and gallic acid.

From "The Literary Digest."FIG. 67.—INK-CRYSTALS, AS SEEN THROUGH A MICROSCOPE.

"By allowing the evaporation to proceed slowly, it is quite easy to watch the formation of the crystals. The geometrical figures are more or less perfect cubes, pyramids, lozenges, crosses, needles, etc., the pyramids being formed by cubes superposed one on the other, as in the pyramids of Egypt. Theflowersin our illustration are formed by the union of crystals, each of which represents the petals or sepals of a flower. The Maltese cross—the crucifer or four-leafed flower—is the normal regular form, but multiples of four frequently occur, by the formation of new crystals in the intervals; and also by the accidents of crystallization, we get flowers of three and five petals, resemblingRubiaceae, lilies, orchids, violets, etc."

Although a lens is the most important part of the photographer's apparatus, it is not absolutely necessary for the production of photographs. Very good pictures can be made by means of a pinhole. Remove the lens from the camera, and insert in its place a sheet of thin, hard cardboard. In the centre make a tiny hole with a fine-pointed needle made red-hot. Another method is to make a large hole in the cardboard, and paste over it a piece of tinfoil and make the pinhole in this. The essential point is that the hole be perfectly round without any burring at the edges. The most perfect arrangement can be obtained by getting a watchmaker to drill a fine hole through a piece of sheet metal. The diameter of the hole should not be greater than one-fiftieth of an inch. Whatever is used, cardboard or metal, it should be blackened all over to prevent the reflection of light in the camera. The focusing glass should be brought within about 6 inches of the hole. Owing to the small amount of light admitted, focusing is very difficult. It can be done by pointing the camera towards the sun and focusing its image. For the same reason the exposure is very long, ranging from ten minutes to half an hour; it is, in fact, difficult to overexpose.

Negative by F. C. Lambert. From Anthony's International Annual, 1894.FIG. 68.—PINHOLE PHOTOGRAPHY.

(Photograph made through a slit without a lens.)By Roland Briant. FIG. 69.—THE WHITE ROBE OF NATURE.

It is usually stated that no focusing is required, the larger the plate the wider the angle, but according to Prof. Pickering, 12 inches is the maximum distance for sharp work.

Peculiar diffused effects can be obtained by using a fine slit in place of the pinhole. The picture shown on page82is an example.

We have already described the various remarkable photographic pictures which may be taken by successive exposures with the same individual in different positions against a perfectly black and non-actinic background. This, however, is not easily obtained, and a French photographer, M. Bracq, has invented an ingenious attachment to a camera by which the same effects may be obtained with any background and under the ordinary conditions of amateur photography. The following description is fromLa Naturetranslated in thePopular Science News.

FIG. 70.

The apparatus, Fig. 70, is attached to the back of the camera, and consists of a frame suitable for holding the usual ground glass, or plate holder. Directly in front of the plate holder is placed an opaque screen perforated with a horizontal slit the width of the photographic plate used. By means of a screwand a crank the screen with its opening may be made to move up and down before the plate, thus allowing all parts of it to be successively exposed. A pointer connected with the screen shows the position of the slit at any time when it is covered by the plate holder.

The operation of the apparatus is evident from the above description. To take the picture illustrated in Fig. 71, for instance, the table with the boy upon it is placed in the proper position and supported by planks, another table, or in any convenient way. After properly focusing it on the ground glass, the screen is screwed down till the opening is at the bottom of the camera, and the plate holder being placed in position, the slide is drawn and the handle turned till the indicator shows that the opening has reached a point corresponding to the image of the bottom of the table on the plate. The slide is then replaced in the plate holder, the table and its support removed, and the boy placed in the second position, and the exposure continued by screwing up the screen until the entire plate has been impressed with the double image, which, upon development, appears as shown in the illustration.

FIG. 71.

The perforated screen may also be made to move horizontally as well as vertically across the plate, and by a combinationof the two directions the same individual may be taken four or more times in different positions in the same photograph. Many amusing and astonishing effects may be obtained by the simple means which will readily suggest themselves to any practical photographer.

By the use, or rather the abuse, of a lens having a very wide angle, say, 100 degrees, some very amusing effects can be obtained by apparent exaggeration of perspective. We say apparent advisedly, for if a view made with one of theselenses, say of 5 inches focus, be viewed by the observer at a distance of 5 inches from the eye, the perspective will appear correct; but, of course, this is never done under ordinary circumstances. Every person, unless extremely short-sighted, will hold a photograph at a distance from the eye of about 12 or 14 inches.

FIG. 73.—A WIDE-ANGLE STUDY.

The effect of using a wide-angle lens under ordinary conditions is to make objects in the foreground appear ridiculously large, while those in the background have a diminished appearance. Fig. 72 is an example of this; it is hardly necessary to observe that the gentleman's pedal extremities were not so gigantic as represented in the photograph. Fig. 73 is another and scarcely less painful example of this exaggeration.

In thePractical Photographer, some time ago, it was humorously suggested that sportsmen could, by means of the camera, bring home apparently indisputable evidence as to their skill or prowess. Thus, for instance, you and your friend Jones have been out fishing together, and realized the truth of the old saying about anglers—i.e., "a worm at one end of a rod and a fool at the other." You have, however, managed to catch a fish (any sort will do) about the dimensions of a good-sized sprat. It is the usual custom of anglers, I believe, to view their captures through magnifying-glasses before discoursing upon them. A better plan, however, is to photograph your fish, and then there can be no dispute whatever, because it is the popular belief that photography cannot lie. However, all that is necessary is to hang the fish in front of the camera to the bough of a tree, we will say, with a piece of black thread. You then retire several paces behind it, holding up your arm as if you were holding up the fish. Your friend will then adjust the camera so that the fish just comes under your hand, focuses, places a very small stop on, so as to get everything sharply defined, and makes the necessary exposure. Thus it is possible, with a little trouble, to obtain everlasting records of your marvelous day's sport, for you can easily make yourself appear to be holding a fish of gigantic proportions—say, 5 ft. long, or so. Fig. 74, 75.

FIG. 74. and FIG. 75.

Our illustrations are from "Photographic Pastimes" by Herman Schauss.

With a very wide-angle lens it is also possible to make a photograph of a little suburban garden, and it will appear to resemble a park or palace grounds. This is a trick often adopted by auctioneers and estate agents, so that in viewing photographs of property, it is really impossible to form any safe idea regarding the place itself.

Amusing caricatures may be obtained by deforming the sensitive surface of the negative. The accompanying conical portrait is one.[6]

[6]From "Les Recreations Photographiques."

FIG. 76.

To depict the features of a person on a paper cone is not an easy matter; whilst to obtain them by photography is a tolerably simple operation.

FIG. 77.

FIG. 78.

Having glued on the interior face of a plate-holder (the slide being drawn), in the place of a sensitive plate, a cone made of strong cardboard, superpose on it an unexposed film which has been cut to the form of the development of the cone (as shown in Fig. 77). The film is secured by means of two or three pins. Having focused on a point of the subject in a middle plane, the ground glass is afterwards drawn back a distance equal to half the height of the cone, taking care not to derange either the subject or the objective. To obtain a sharp image a very small diaphragm must necessarily be used, but with a rapid plate and good light that is of little moment. The camera should be placed in the dark room, the lens being inserted in a hole in the partition just its size, and the subject in the adjoining apartment opposite the lens—this because the cone will not allow the plate-holder to be closed by the slide.

Fig. 76 shows the arrangement of the camera and holder. The exposure made, the film is developed, as usual. The negative gives a print deformed as shown in Fig. 76. The original, if not grotesque appearance of the head disappears when the print is rolled into a conical form and the observer places his eye in the prolongation of the axis of the cone. Fig. 78 shows the head as seen under these conditions.

Prepare a saturated solution in water of the crystals of thiosinamine, and add from two to eight minims of it to an ordinary pyro or eikonogen developer. Expose rather less than usual. The effect of this addition to the developing agent is an entire reversal of the image, a positive instead of a negative being obtained. Ammonia will assist the reversal. Colonel Waterhouse, the discoverer of this process, recommends in some cases the plates being subjected to a bath of 5 per cent nitric acid and 3 per cent potassium bichromate before exposure, followed by a thorough washing.

In the very earliest days of photography this term was applied to what would now be considered very slow work indeed. We now usually apply this term when the exposure does not exceed one second. In some cases this only amounts to the one-thousandth part of a second. This exceedingly brief exposure is usually given to the plate by means of a suitably constructed shutter.

The immense strides that have recently been made in instantaneous photography, owing chiefly to the advent of the dry-plate process, have caused photography to become useful to almost every branch of science.

To Muybridge and Anschutz we are greatly indebted for the strides made in instantaneous photography. These gentlemen have succeeded in photographing moving objects hitherto considered impossible to be photographed. Galloping horses, swift-flying birds, and even bullets and cannon balls projected from guns have been successfully photographed, showing even the little head of air driven along in front of the bullet.

FIG. 79.

Both Muybridge and Anschutz also succeeded in making series of twenty-four or more photographs of a horse during the time it makes a single leap, and thus illustrated its every movement. The value of these and other possibilities with the camera for artists cannot be overestimated. Its aidto meteorologists in photographing the lightning, to astronomers in stellar, lunar and solar photography, and to all other sciences would require a work as large as this to describe.

By Lt. Joachim Steiner.FIG. 80.—INSTANTANEOUS STUDIES.

For the making of instantaneous pictures a large number of suitable cameras have been devised. In most of these the lens is a very rapid one, and in some cases so arranged that all objects beyond a certain distance are in focus. With an instantaneous camera a secondary image is necessary, so that the right second can be judged for making the exposure. This is usually produced by a finder. In making instantaneous exposures the following tables may be useful:

Approximate distance

A man walking 3 miles per hour moves4-1/2Feet per secondA man walking 4 miles per hour moves6Feet per secondA vessel traveling at 9 knots per hour moves15Feet per secondA vessel traveling at 12 knots per hour moves19Feet per secondA vessel traveling at 17 knots per hour moves28Feet per secondA torpedo boat traveling at 20 knots per hour moves35Feet per secondA trotting horse36Feet per secondA galloping horse (1,000 yards per minute)50Feet per secondAn express train traveling at 38 miles an hour59Feet per secondFlight of a pigeon or falcon61Feet per secondWaves during a storm65Feet per secondExpress train (60 miles an hour)88Feet per secondFlight of the swiftest birds294Feet per secondA cannon ball1,625Feet per secondAn object moving—1 mile per hour1-1/2Feet per second2 miles per hour3Feet per second5 miles per hour7-1/2Feet per second6 miles per hour9Feet per second7 miles per hour10-1/2Feet per second8 miles per hour12Feet per second9 miles per hour13Feet per second10 miles per hour14-1/2Feet per second11 miles per hour15Feet per second12 miles per hour17-1/2Feet per second15 miles per hour22Feet per second20 miles per hour29Feet per second25 miles per hour37Feet per second30 miles per hour44Feet per second35 miles per hour51Feet per second40 miles per hour59Feet per second45 miles per hour66Feet per second50 miles per hour73Feet per second55 miles per hour80Feet per second60 miles per hour88Feet per second75 miles per hour110Feet per second100 miles per hour147Feet per second125 miles per hour183Feet per second150 miles per hour220Feet per second200 miles per hour257Feet per second

With these tables it will be very easy to find the distance that the image of the object will move on the ground-glass screen of the camera. To do this, multiply the focus of the lens in inches by the distance moved by the object in the second, and divide the result by the distance of the object in inches.

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