The effect of the horizontal and vertical swing-back is identical, as is obvious if the camera be placed on its side, for the horizontal swing becomes vertical, and vice versa. If the camera be set up plumb, the effect of using the vertical swing-back to its extreme limits (which are determined by the mechanical construction of the camera) is to lengthen objects in the direction of their obliquity and to sharpen them. What does this mean from an art point of view? It means that as a rule it throws the whole picture out of drawing, the relative positions of the planes are altered, the relative definition in the planes is altered and therefore the relative values, and therefore as a rule the picture, is artistically injured. This rule-of-thumb use of the swing-back arose, no doubt, from the practice of those craftsmen, untrained in art, whose aim was the production of "sharp" pictures. The only legitimate extensive use of the swing-back is when the camera is tilted before an architectural subject, when it is quite correct to have the ground-glass plumb, although for our part we deem the tilting of the camera to be undesirable. The swing-backs can, however, be used, with the greatest caution, in artistic work, and their value can scarcely be overrated, but it requires great knowledge to use them appropriately. The subtle changes in the drawing and composition of a picture which can be obtained by an intelligent use of the two swing-backs, make them, to those who know how to use them, most valuable tools. But if the beginner will take our advice, he will keep his ground-glass plumb, and his horizontal swing-back square, and never venture to alter either until he has thoroughly mastered his technique, and has some insight into the principles of art. The use of these swing-backs seems so easy, as of course it is, when "sharpness" is all the desideratum and embodiment of the operator's knowledge of art, but in reality none but artists know their real value. By their means, the impression of the whole scene can often be more truly rendered, and things can be subdued and kept back in the most wonderful manner; and since we wish to get a true impression of the scene we are interested in, not a realistic wealth of detail, it can be easily understood how invaluable are the swing-backs when used cautiously. Muybridge's galloping horses are in all of their movements true, but many of these are never seen by the eye, so quick are they. On the other hand, the student, if he goes to the British Museum, can see in the Parthenon Frieze that the sculptors in some cases carved the legs of the farthest off of three horses in higher relief than those of the nearer horses, but if he goes off a few paces and views the carving in its entirety, he will see the true impression is gained; the nearest legs look the farthest off, and so the work is true in impression, though not true in absolute fact. And though the use of the swing-back makes the drawing a little false, yet if the lens we shall describe hereafter be used, the falsity is so very slight as to be hardly noticeable, while it is far more correct than any human hand guided alone by a human eye can render it. With art as with science, nothing is absolutely correct, the personal equation and errors of experiment must be allowed for, but the results are true enough for working purposes.

On impression and fact.

Pin-Hole Photography

By perforating a thin metal plate with a minute hole, large enough only to admit a pin's point, and fitting it to the front of the camera in place of the lens, an image will be thrown on the focussing screen, as the piece of ground glass at the opposite end of the camera is called. If the image be received on to a sensitized plate, it will be impressed on the plate, and can be developed in the ordinary way. Were it not for the great length of time required for exposure, it would be a great question whether any lens at all need be used in photography, but since the exposures required to produce pictures without lenses vary roughly from one to thirty minutes, this method cannot be seriously considered here, for, as we shall show, within certain limits, the quicker the exposure the better; nevertheless, the drawing of pictures taken in such way would obviously be correct. In cases where the length of exposure is immaterial, this method would be a worthy field for experiment.

Accidents To The Camera

Test for register.

The student must be careful to see that the inside of the camera is a dead black, and that it keeps so. At times the camera may leak or get out of register, that is, the plate does not exactly take the place of the ground glass, in which case he should at once send it to the maker. Should the student wish at any time to test the register of his camera, he has only to pin up a printed card and focus it as sharply as possible, using a magnifying glass, if one is at hand. Then load the dark-slide with a plate of ground-glass, and after sliding it into position, open the slide (if a double-back) when the image will be seen on the ground-glass plate, and its sharpness can be noted. If perfectly sharp, the camera is in register.