THERE

HERE is no problem in photography that presents to the tyro such a perplexing uncertainty as does the question of exposure. The purchaser of a camera receives therewith a book of instructions, describing minutely every detail-from the loading of the plate-holder to the adjustment of the swing-back-but on the subject of exposure the directions are painfully brief. The instructions accompanying the cheaper grades of cameras usually recommend “snap shots" in strongest sunshine only, while for cloudy days the "time" is stated to be from 5 to 15 seconds, and from 5 seconds to 2 minutes for interiors. Then, as though these vague statements were not sufficiently discouraging, the directions wind up by saying, "Nothing but long experience and many failures, accompanied by patience and perseverance, will enable the novice to correctly time his exposures." In consequence of this, snap-shot cameras and instantaneous exposures are made in every possible case, simply because the inexperienced "camerist" thinks time exposures more uncertain.

Now, let us consider this: If, with a given amount of light, an exposure of of a second on a fast plate is correct for a certain subject, then, in the same light, of a second would be an overexposure of 100 per cent., and of a second would be a corresponding underexposure. How are you going to distinguish between these extremely small intervals of time? Again, supposing the shutter were of a constant speed-say of a second-and everything was ready to "press the button" with the sun under a cloud, and just as the shuttersnapped the sun came out full strength. Then the subject would receive twice the illumination expected, and the plate would be overexposed.

Now, suppose we go to the other extreme, and take a very slow plate-in fact, the very slowest, which requires about 20 times the exposure that should be given the fastest. The above subject and conditions would require on this plate an exposure of 1 second, which even a wild guesser at intervals of time

could not overdo 100 per cent.; and, if the f lens were well "stopped down"-say to making the proper exposure 8 seconds, an error of 10 per cent. would be almost impossible, and, even if it were made, would do no appreciable harm.

From this we see that time exposures give more latitude within the safe limit than does the snap shot, and at the same time are much more readily controlled.

If, then, we can ascertain, within 10 or 15 per cent., what should be the proper time for any given subject, we can start out on a kodaking trip in any kind of weather, with the assurance that our successful pictures will run pretty nearly 12 to the dozen

exposures.

In these days of "you-press-the-buttonand-we-do-the-rest" cameras, comparatively few of the alleged amateur photographers know anything about time exposures. Many owners of high-grade cameras seldom use a diaphragm smaller than will admit of a snap shot. Not one amateur in fifty appreciates the value of a real slow plate; and the use of color screens and isochromatic plates is considered by many to be confined to experts or cranks.

Now, if you were able to secure the exact exposure for any subject, on any plate, and in any kind of weather, would you experiment a little with the slow and isochromatic brands? If you would, you could learn something at every attempt you made, and if you wouldn't, it shows you are not destined to become a thoroughbred camera crank. It is quite generally known that it requires a shorter exposure for an open landscape than for one possessing considerable foreground, and that an outdoor portrait needs more time than the foreground of a landscape, all other conditions being the same.

This is all very good so far as it goes, but even if we know the ratio of exposures for these different subjects, it is of little value to us, unless we also know the exact exposure for at least one of them. The experienced

photographer exposes according to his judgment, the careless amateur makes a rough guess, the kodaker presses the button and trusts to providence, or luck, or some other uncertainty, and all three go into their several dark rooms expecting to get satisfactory results. The amateur and the kodaker (if he develops his own work) may endeavor to augment their chances of success, by developing their plates in a clothes closet, where there is no running water, and where the light is furnished by a candle in a cigar box, the front of which is covered by a piece of yellow post-office paper; while the hypo is conveniently placed in a soup plate on a soap box near by.

By a strange irony of fortune, such workers as these occasionally secure quite passable results, while the careful operator often fails in his undertaking. This, however, is no argument against careful work, and it is for the careful man only that the following remarks are intended.

A piece of Solio or Albuma paper will show a change of color, after an exposure of 5 seconds to the full sunlight, while an exposure of 20 to 60 seconds will render it a reddish-brown color. Now, if the strength of light that will turn Solio to a given shade in 5 seconds will properly impress a landscape on a fast plate in % of a second, it stands to reason that an intensity of light that fails to turn the Solio to the given shade until 50 seconds exposure, will require of a second to impress the above landscape on the plate, all other conditions being the

same.

Upon this principle are based a number of instruments with different names, but all intended to present to the photographer a royal road to correctness of exposure. The simplicity of the instruments not infrequently leads the user to become careless, and to blame his apparatus for his own blunders; but, carefully and judiciously used, an exposuremeter, or photometer, is a valuable instrument and a reliable instructor.

In Fig. 1 is shown a form of photometer, which can be easily made, is reliable to use, and costs next to nothing. It is intended to be pasted on the face of a watch, but can be printed on celluloid or on a piece of cardboard, if desired. The easiest way to make one would be to photograph Fig. 1 with an ordinary camera, thus reducing it to the size of the watch dial, and pasting a print of it on the crystal, as hereafter described.

First tack or pin this page against the wall, near a window, where it will be evenly

illuminated by a strong north light; then place your camera on a table, in such a position that the center of the lens is on a line with the center of the dial in Fig. 1, making sure that the camera is level, as otherwise the resulting negative may show an elliptical dial instead of a circular one, which would not do at all. Focus to get the figures sharp, and then stop the lens down to Expose on a slow plate (Seed 23) for 30 seconds, or on a fast plate for 12 seconds; develop with a hydroquinone developer containing at least 3 grains of potassium bromide to each ounce. The resulting negative should come up slowly, and present perfectly transparent lines on a dead, opaque ground. Carry the development forward until the plate is nearly black; then wash, fix, and dry as usual.

Now make two prints from this negative, and after fixing them (they need not be

toned), carefully cut out the two dials with a sharp knife. On the larger, outside dial, the heavy figures from 8 to 64 correspond to the focal values marked on the lens stops, and the light figures from 2 to 640 are the experimental exposure figures explained below. The figures on the inside disk are the exposures in seconds or minutes, according to circumstances.

Carefully cut the disks apart, and mount them upon the face of your watch as follows: Paste the outer ring on the dial of the watch so that the figure 40 of the exposure table is over the XII of the dial, and the number 22 of the top-scale is over the VI of the dial. Then cut the segment ab ce out of the smaller disk, and paste this disk to the inside of the crystal of the watch, so that the figures show through the glass, being careful to get

the point e exactly in the center, over the hand pinion, in order that, when the crystal is revolved in the basil, the radial lines of one circle will correspond to those of the other. If desirable, the dial, Fig. 1, can be cut out of the page and used, instead of photographically reproducing it.

Now, take a piece of yellow post-office paper or heavy Manila wrapping paper, and cut out a piece 14 inches wide and 4 inches long, as shown at a bed in Fig. 2. Just below the top-about inch-cut a rectangular hole e, which shall be inch wide by inch long. Then fold the paper over on the

the tint b. The watch crystal is now revolved in the basil so that the figure on the experimental exposure scale, corresponding to the number of minutes or seconds the paper was exposed, is opposite the general title of subject of which the photograph is to be takenthen, on the opposite side, under each size of stop, will be found the correct exposure for that stop in minutes or seconds.

For instance, suppose we are photographing an open landscape, with no foreground within a hundred feet; we find, on consulting our photometer, that it required 40 seconds to turn the silver paper to a shade between a and b. We then set the 40 of the upper scale opposite the subject Landscape with distance; and over 8, on the lower scale of stops, we find the exposure would be of a second, or, with a small stop, we find under 64 the time required would be 14 seconds. This would be with the fastest plates, while the slower ones would require proportionately longer exposures, according to the table given below.

Now, to determine the proper tints for a and b, it is necessary to work backwards, so to speak. Set up your camera on a dull or cloudy day, and focus on a fence or some foliage not more than 25 feet distant; close your shutter, put in stop, and, after placing your plate-holder in the camera, withdraw the slide 1 inch, and expose the plate for 1 second; close the shutter, and withdraw the slide another inch, and again expose for

described further on. One of these strips b is darker than the other a, in order to establish a reliable comparison.

Now, before using the instrument, a piece of Solio, Albuma, Aristo, or any other printing paper, is cut into strips inch wide, one of which is inserted in the envelope, as shown at d in Fig. 3. When the instrument is to be used, and it is desired to determine the proper exposure for a given subject, you take out your watch, and pull the printing paper out a trifle, so that a fresh spot comes under the opening e, and note the number of minutes or seconds required to turn the paper a shade darker than the tint at a, but not so dark as

1 second. Repeat this operation five times, and carefully develop the plate. Select, from the five 1-inch strips, the one that is the best quality of negative, and use the time of its exposure as the key to the situation. Suppose the strip that received 2 seconds' exposure were to be the best of the five. Turn the 2 of the exposure scale to the 64 of the stop-dial, and on the outside scale opposite Landscape with foreground will be found 30 seconds as the time required to turn the paper the desired color. Expose a piece of the paper you are to use, for 30 seconds to the same light which fell upon the object you were photographing, and then, in a subdued

light, tint b a little darker and a a little lighter than the shade to which your paper has turned. The closer these two tints approach the color of your paper, the more accurate will be your instrument.

In photographing through a color screen, it is simply necessary to use the screen with the photometer in estimating the exposure, in order to determine how much time is required to offset the color of the light. With orthochromatic and isochromatic plates this is not so important, but it gives a basis to work on in any case.

If it is not desirable to use the photometer

as an appendage to your watch, a very neat instrument can be made by printing the two dials on Seeds positive films, and fastening them together with an eyelet at the center. In this case, the outer circle can be printed on a square piece of film, on the front of which the smaller disk is fixed to revolve, while on the back can be copied the table from the preceding page, which shows the relative speeds of different brands of plates.

In using any of the plates given in the table, multiply the time, as found on the photometer, by the number at the head of the column in which the brand of plates is named.

OR

NCE upon a time, as the story books say,

foolish" was engaged as helper in an English machine shop. Everybody knew he was foolish, for it was written all over his face. His mouth was always open, he never thought of such a thing as breathing through his nose, and his eyes looked everywhere and nowhere. He talked with a "thlight lithp," leaned forward as he walked, grinned when spoken to, and went about his work with as much apparent intelligence as a somnambulist. They called him "Billy."

When he had nothing particular to do himself, Billy had a habit of staring vacantly at others; in fact, he was always present where work was being done, and at all shop conferences he seemed to resolve himself into a silent investigation committee. Whether or not he added to his slender stock of knowledge, at these conferences, or mentally criticized what the "wise men" said, will never be known, but something that occurred at one of them is our present excuse for writing about him.

There had just been brought into the shop a new belt pulley, bored and key-seated, ready to slip on the end of the shaft. The pulley was lifted up and an attempt made to put it on the shaft, when it was discovered that the bore was too small-that the pulley would not go on. By this time, of course, Billy was around, all eyes and mouth, gazing at the pulley as if he thought it was alive, and was expecting it to get up and walk out of the shop.

The two men who were handling the pulley were nonplused. They put it down, and

sending Billy to bring the foreman, stood waiting. The foreman and Billy soon returned. The men, after explaining the trouble, were told to try it again. They did so, but it was of no use. The bore was evidently too small. "Did you send them a gauge to bore it by?" asked the foreman.

"Yes, sir," said one of the men, "and I'm quite sure the gauge was right.”

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Well,' ," said the foreman, "I don't know what to think of it. Billy, go find the superintendent, and ask him if he can come around for a minute or two."

In due time the superintendent appeared, and for his special benefit they tried the pulley once more. Then, as they put it down for the third time, the Boss happened along-wanted to know what the trouble was-had the matter explained—and then, along with the foreman, superintendent, and others who had gathered around during the conference, looked very serious. It was at this moment, when all was still and silent, that Billy, who had been staring about, looking more bewildered than usual, drawled out these remarkable words:

"Doant ye think it maat goo on, if ye wuth to turn it tother way raound?"

For a moment the "wise men" were too astonished to utter a sound. Then the Boss laughed; then they all laughed; then they "roared," because it was such a capital joke. But Billy didn't say a word. He just waited; and in a little while he got his reward. At a sign from the Boss, his suggestion was tried; then they all stopped laughing, for, sure enough, when the pulley was reversed, it went on all right.

DIDA

ID IT occur to you when reading the above title that you were at that moment holding in your hands, looking at with your eyes, nay, even touching with the sensitive tips of your fingers, an excellent sample of the very material which the writer has chosen as the subject of an article? Probably not. Indeed, it would have been remarkable if it had, for you are naturally so familiar with the general appearance of the finished article, and so accustomed to reading what is printed upon it-without regard to the material itself-that the mere holding of a quarter of a pound or so of it in your hands has become a trifle of absolutely no significance. For all that, however, paper is an exceedingly interesting material, and, as we shall see, of great importance industrially.

As every one knows, certain spans of time in the world's history are known as the stone age, the bronze age, and the iron age, the reason being that these materials were the principal ones employed in the manufacture of the various tools and implements that were used during those times. The present age may possibly be referred to by posterity as the paper age-so numerous and varied are the purposes to which paper is now applied in the industrial world. And yet, comparatively few people know what paper is, or how it is made.

Paper is a thin felt of interwoven fibers, which have first been finely divided, then mixed into a pulp, and finally rolled into thin sheets and dried. The earliest form of paper used for writing purposes was probably the papyrus of the Egyptians; this was used at least 4,000 years ago. The Chinese made paper from artificially prepared pulp as early as the beginning of the Christian era. It is thought that in its manufacture they used cotton, the bark of trees, and similar materials. The Arabians learned the art from the Chinese, and about 12 centuries ago built a paper factory. It is believed that the manufacture of paper was introduced into Spain by the Moors, and from there spread to the rest of Europe.

As we have said, paper is a thin felt of

interwoven fibers. Many fibrous substances, both vegetable and animal, have, at different times and places, been employed in its manufacture; but animal fibers do not make a good grade of paper, as bleaching agents do not readily act on them; they are also difficult to prepare in other respects. Cotton was one of the first substances used in paper making, and it is fitted for this purpose by the ease with which the fibers can be prepared. The paper made from cotton, however, is rather loose and spongy in texture, unless it contains some linen.

At a very early date, cloth, which is largely composed of interwoven fibers, was used, and for a long time rags formed the principal raw material in the manufacture of paper. Rags from hemp, flax, and cotton are still employed, but woolen and silk rags can only be used in making a cheap grade of paper, as the bleaching agents do not act on the animal fibers. In the manufacture of the finest grade of writing paper, linen rags play a very important part, but during the past half century, the quantity of paper manufactured has so largely increased that the supply of rags obtainable does not nearly meet the demand; for this reason, various fibrous substances have been introduced to take the place of rags. Among these are esparto grass, jute, straw, corn stalks, and wood.

In choosing a material from which to make paper, several things must be considered. The substance should contain a large percentage of fibrous matter, and should be easily freed from other materials; the fibers should be strong, and should knit well, forming a close, compact felt. Straw, when treated to free it from silica, yields a fiber which makes an excellent paper, but the loss of material and chemicals is so great that it has never been very largely used. The root cuttings of jute, and the waste from rope making, are rich in fibrous matter, but the paper made from them is of an inferior quality.

In 1840, F. G. Keller obtained a pulp from wood, by grinding it under millstones, but pulp thus prepared has the fibers so ground