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July 24, 1868.] THE PHOTOGRAPHIC NEWS. 353 inflow; and then it would remain, running in at one end and out at the other without ever starting the syphon at all, but for a very curious and important point, viz. this—that the long leg of the syphon, by going down far below the level of the water in the apparatus itself, gives the water confined in it a very considerable speed in its transit through the pipe, so that the water which only ran quite slowly over the bend of the syphon pipe comes out with quite a rush at the bottom, when it has fallen through some three or four feet. But when water goes through a pipe in this manner—namely, beginning quite slowly as at the top, and running with increased rapidity all the way down—it naturally follows that, the air in the pipe gets entangled with the water and carried down with it. The moment this occurs the pressure of the air on the surface of the water in the washing trough sends up some more water into the short limb of the syphon, and so more and more comes down the longer limb, till in about thirty or forty seconds after the first few drops come over, the syphon is at full play, and emptying the trough as quickly as possible. To ensure the success of this plan, one thing only is necessary, as far as my experience goes ; viz., that the longer limb of the syphon must be as straic/lit as possible; it must have no eccentric bends or curves to cheek the progress of the water which comes over first, for it is on the speed of the first few pints that the success of the whole depends. In setting up an apparatus of this kind not long ago, I found that a bending of the tube only once at right angles, and then carrying it out straight for a few feet, so much took off from the efficiency of the arrangement, that not only would a small influx of water into the tank not start the syphon, but even it did not start when the tank was filled up two or even three inches above the level of the bend ; this I quite account for by the peculiar shape of the longer limb of the syphon, which allowed the air to enter freely at the bottom at the same time that the water was running out, thus requiring main force to setup the proper action, and not, as it should be, the gentle influence of the small but rapid flow of water to begin with. I find that the inflow of the water into the machine is sufficient to cause enough motion in the prints ; this refers to only a moderate number, however; when very large quan tities of prints have to be washed at once, the ingenious apparatus used in Mr. Bedford’s establishment, and de scribed some time ago in the News, is most efficient in keeping up a constant agitation of the water and prints ; it consists of a flapper kept in constant motion in the water by means of a waterwheel turned by the inflow water. When the water is draining out of the washing machine, the prints should not lie on the bottom of the trough, but should be provided with a perforated zinc false bottom on which to drain ; this should be kept from the real bottom by slips of wood, or otherwise, so as to be about half an inch clear of it. I find that nothing can be better than three coats of Bates’s black varnish to preserve the prints from injury by contact with the metallic zinc. This var nish should, it seems, be renewed every three months or so, as it may require it. I remember some time ago seeing au account of some experiments with zinc for washing trays unprotected by any coat of varnish; though, in the particular instance referred to, the prints may not have been marked by the metal, I cannot but think that, in all cases, it must be much better to use a coating of varnish to protect the surface of the paper from the metal. PICTORIAL EFFECT IN PHOTOGRAPHY ; Being Lessons in Composition and CHIAROSCURO fob PHOTOGRAPHERS. by h. p. ROBINSON. Chapteb XXVI. " The vocabulary In use relating to light and shade is utterly inadequate to convey that knowledge ot its phenomena that a painter requires. It com prises merely the terms light, shade, reflection, hall-light, and half-shade. Now all lights—with the exception of those belonging to objects self-lumin ous, as lire, the sun, &c.—are either the reflections ot light from the surfaces of bodies, or transmission of light through those that are transparent or partially so ; the focus of light on a globe is, therefore, as much a reflec tion as that appearance on its shadowed side which, in ordinary language, is called the reflection; and as to the terms half-lights and half-shades, they but express, if literally understood, single degrees among the endless grada tions from light to dark.”—Leslie. CHIAROSCURO —(continued). Although there are, between white and black, an infinite variety of gradations, it will be convenient to divide them into light (I), half-light (2), middle tone (3), half-dark (4), dark (5). if a picture were composed of light and half- light only, the effect would be weak and flat. In photo graphing distant views, which consist principally of light tones, it will be necessary to introduce some dark object in the foreground to give force and consistency to the whole. Turner has carried this principle to perfection. Many of his most beautiful pictures, full of air and space, consisting chiefly of delicate greys and blue, are brought into focus by the introduction of the dark foliage of the stone pine, sup ported by some dark spots in the foreground, which is gene rally light, the darks being united to the lights by delicate and infinitely varied half-tones in the middle distance. Rembrandt’s method was exactly the reverse of this, but the same in principle; his pictures are composed of half dark and dark, having one small focus of brilliant light, united in a magical manner to the darks by half-tone. The marvellous effect of his pictures is due, in my opinion, more to the judicious management of the half-tones than to the strong contrasts and forcible effects of his light and shade. In his pictures and etchings will always be noticed a wonder ful transparency in the shadows, which is almost entirely due to the half-tones with which they are associated. Claude, Turner, and Rembrandt were alike in their manage ment in one respect: they always forced the brilliance of their lights by the opposition of the strongest darks. When Claude and Turner represent the sun, they place near it their darkest dark. This effect will always be seen in nature ; if the sun is setting behind a tree, the tree will be darker than any other object in the scene. In Rembrandt’s portraits the head is often covered with a black velvet cap to increase by contrast the brilliancy of the face, and it will be observed that the other parts are, although dark, in half- light in comparison. This principle is carried out to a great extent in the pictures of Adam-Salomon, where tho dark velvet so often introduced plays a most important part in the economy of light and shade. Light and shade varies so much with the subject to be re presented that it can scarcely be reduced to anything like a system. But there are a few general arrangements which the photographer would find valuable to have always before him, and they are only, as it were, duplicates of the laws that govern composition. In chiaroscuro, as in the composition of lines, the centre is the weakest -part of the picture. Neither the principal object nor the chief light should be situated in that place where lines drawn from the opposite corners would intersect. A position either immediately above, below, or at the side of this point would better satisfy the requirements of pictorial effect. In a portrait the head, which is the principal object, and light, would be above this position, in a more or less degree, according to the stature of the individual. When the light spreads through the picture it should never be allowed to form either a horizontal or vertical line. This refers to the general mass of light. The horizontal bars of light seen at twilight are often very beautiful, and their formal straightness give a grandeur and a sentiment of repose to be produced in no other way. This rule, in
