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282 THE PHOTOGRAPHIC NEWS. [June 12, 1868. Fi7. i. Fig. 2. A disregard of this rule has spoilt the effect of many otherwise good pictures. In some photographs we see the figure walking almost out of the picture, for the sake of showing the last coils of the long caudal—almost prehensile —appendages with which ladies sweep the dust, thus sacri ficing the head for the tail. The apparent height of the person represented depends almost entirely on the position of the figure on the plane of the picture. The taller the person, the nearer to the top COMBINATION NEGATIVES. BY J. B. MIDDLETON. I think all persons who are interested in the develop ment of photography as a fine art will admit the vast importance of the possibility of employing parts of two or more negatives in the production of one picture, for it affords the artist more ample scope for the exercise of his inventive faculties, and enables him to obtain results which would be impossible by other means. Hitherto, I believe, this has always been done in the printing process, whereby, in spite of the greatest care and skill, many proofs are spoiled by the unequal printing or imperfect joining of the parts. Thinking on this matter some time back, it occurred to me that it might be possible to obviate much of this difficulty by the production of what may be called a compound nega tive in the copying camera by means of converging lenses thus:— The copying camera must be large, and have a front con structed to carry as many negatives as may be required (perhaps four would be the largest number that could be conveniently used), which should be placed as closely together as possible; of course all parts of the negatives which are not requ ired in the picture must be carefully stopped out. The lenses inside the camera, of which there must be one for each negative, should be mounted in such a manner as to have free motion in all directions (similar to that of a ball and socket joint), and should be provided with screw or other mechanical adjustments, so that they could be readily arranged in any position. Then, by causing the lenses to converge in various degrees, the image of the required part of one negative could be brought to fall exactly on the part of the focussing screen occupied by the corresponding “ blocked out” part of another, and a transparent positive could be taken (which, if required, could be improved by hand “touching ”), and from that any number of compound negatives might be obtained in the ordinary way. By em ploying lenses of long focus the angle of convergence would be diminished, and the risk of distortion from using the lenses obliquely would be less. I do not know whether this idea is new or not, but if there should be any novelty or practical value in it, the photographic world is perfectly at liberty to make the best of it. diamond is esteemed equal to that of a similar rough crystal of twice the weight, exclusive of the cost of workmanship. The weight, and consequently the value, of diamonds is estimated in carats, one of which is equal to four grains ; and the difference between the price of one diamond and another, ceteris paribus, is as the squares of the respective weights. Thus the. value of three diamonds of one, two, and three carats’ weight is as one, four, nine. The average price of diamonds that arc worth working is about two pounds Stirling for the first carat, and consequently in wrought diamonds, exclusive of the cost of workmanship, the cost of the first carat is eight pounds. The largest known diamond was in the possession of the Groat Mogul; it weighs upwards of 279 carats, and is in size and shape equal to about half a hen’s egg. Diamonds were more rare, and of course dearer, than they have been since the discovery of the Brazilian mines. The uses of the diamond are principally in ornamental jewellery. It is also employed by glaziers for cutting glass ; by lapidaries, for cutting and engraving upon the hardest gems ; and in the finer kinds of clockwork. The mineralogical situation of the diamond is not very well ascertained. It occurs in India in detached crystals, in a kind of indurated vitury gravel, not far from the surface of the ground; but whether or not this is its native bed is unknown. The diamond mines of India extend throughout the whole chain of the Ghauts, from Bengal to Cape Cor- morine. Many of them are totally abandoned, the chief that are now worked being situated between Golgonda and Musulipatam. PICTORIAL EFFECT IN PHOTOGRAPHY; Being Lessons in Composition and CILaRoscURA Fon PHoTOGRAPHERS. BY II. p. ROBINSON. Chapter XX. tl Thus bad begins, and worse remains behind !"—SHAKESPERE. " If there be no room, thrust away the meaner parts, and give praise that thou retaineth the chiefer portion.”— LAIRESSE. Portraiture—continued. A great deal of the effect of a portrait will depend on the position the figure occupies in the picture. A glance at the illustrations will show this. As a general rule, if the head be not equidistant from the sides of the picture, there should be more space allowed before the face than behind, as in Fig. 1. The awkward effect of the reverse of this will be seen in Fig. 2.