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This “ proof,” like the others, is exceedingly loose and inexact. We are not told at what distance the eye is to be placed, or at what height above the level of the table. As a matter of fact, if the position of the eye is such that the coins come near together in the field of vision, there is no doubt about it their relative proportions are seen, and the smaller coin does not appear relatively larger than it really is. When the level of the eye is much raised, so that the penny is not near enough for comparison, and when it comes far from the limit of distinct vision, it is easy to assume disproportionateness. If, now, the first and leading proposition of Messrs. Emerson and Goodall is a true one, the object seen on the upper part of the retina—the lower half of the eye, they call it—appears smaller in scale than those projected on the lower half, and the penny, on this account, seems smaller than it really is. Then, if the image of the penny is made to fall on the lower half of the retina, by making it a raised fore ground object, it should appear as much larger in the second case as it did smaller in the first. It seems strange that the authors of the paper under discussion should not have thought it worth while to make this experiment, which is simply the complement of the other. I have here an appliance with which it can be done. There is a horizontal bar lying on the table, fitted with three vertical arms. From the vertical arm at one end of the horizontal bar a halfpenny projects. At a distance of eighteen inches in front is a second vertical arm, with niches in which pennies are fitted above and below the height of the half penny. Eighteen inches, again, in front of this is the third vertical arm, in which an eye-hole is bored, level with the halfpenny. A large sheet of white card is placed behind, so that we are not confused by seeing different backgrounds to the different coins. If the halfpenny is looked at direct, I cannot find that the one penny appears to differ from the other in size, nor has anyone else to whom I have shown it found it to be the case. It may seem to some to be a waste of time to fit up even such an appliance, and it certainly might rather be expected that Messrs. Emerson and Goodall would have done it themselves before announcing their propositions; but, when it is remembered how many people were mystified by the quasi-scientific theories put forward not long since on the subject of definition or focussing, it may not be wasted time after all. It is remarkable that Messrs. Emerson and Goodall deal with near objects only as below, and distant objects as above. The experiment with the two pennies shows the near object both as above and below. If their proposition is true, that the lower half of the eye sees things on a smaller scale than the upper, and for this reason a perspec tive drawing surprises us by making the foreground objects look large, then such foreground objects as are above the distance should surprise us by appearing too small in the perspective drawing or photograph. Perhaps one of the most familiar instances of a near object above the central distance is that of a chandelier depending from a ceiling when the interior of a room is photographed. It may bo enough simply to ask the question whether such an object really does surprise us by appearing too small in the picture. A point, however, that it seems very strange should have escaped the notice of the writers, is that we see the photograph or perspective drawing with the same eyes that we see the objects of nature. If, therefore, it were a fact that a natural object, when at the bottom of the scene, appears smaller to our eye than it comes in mathe matical perspective, then the same object in the lower part of the drawing, falling on the same diminishing part of the eye as the original object would, suffers a like reduction also, and the true effect will still be produced. The lines from the various points in a drawing in mathematical per spective or in a photograph, seen at a proper distance, fall upon the same parts of the eye as the lines from points in the natural scene would do, and both would suffer alike from the want of equality of vision assumed by the authors. The case is very similar to that of the supposed necessity for the lens to simulate the defects of the eye, which was for some time maintained by Dr. Emerson and a few followers. Is there any difference between photographic and true mathematical perspective and perspective used by painters ? Sometimes there is ; painters allow themselves licences. If an interior has to be represented, a photo grapher must photograph it from a distance limited by that to which he can remove his camera. A painter will often represent the interior, as far as the leading lines are concerned, as it would appear if the observer were so far removed as to give what is called less violent perspective. There is no difficulty in doing this to anyone acquainted with the rules of perspective. If, however, the drawing is to be true throughout to what would be seen at the selected distance, care must be taken to obliterate such objects—as, for instance, a side window—which at a greater distance would be hidden by a pillar, and, in some cases, to show objects covered in the near view, but which would be exposed to view farther off. Again, in painting figures, they will generally be repre sented as they would appear (with regard to comparative size of advancing the retiring portions) at such a distance as not to make these differences of size conspicuous. Sometimes, indeed, they are painted rather with the know ledge of the equality of the retiring and advancing portions of a figure than with the effect which perspective has in enlarging or diminishing them. Are these things passing conventions, and will photography cause any change in them, as it has done with other conventions ? Time will show. We have recently tried the improved sulphokinone developer sent to us by the Fry Manufacturing Company. Thedeveloper is in two solutions, which for a normally exposed plate are mixed in equal parts. In our hands the developer gives very fine results, especially for lantern slides. Several plates can be developed in the same mixed solution before it shows any sign of exhaustion. | Photographing the DEAD.—It appears that a somewhat morbid custom exists among .the Viennese of having the dead bodies of children and other persons dear to them photographed, and for this purpose the corpse used to be taken to the photo grapher’s studio. The attention of the sanitary authorities having been drawn to the danger of the dissemination of infectious disease by this practice, a decree has been issued by the Austrian Minister of the Interior absolutely forbidding the photographing of corpses in studios open to the public, and the photographing of bodies of persons who have died of any infectious disease by professional photographers, even in private houses. Exception is made of cases in which such photographs may be required for police or medico-legal purposes. In the case of persons who have died of non-infectious disease, the corpses may be photographed at the private residence of the deceased, subject to the approval and on the responsibility of the medical official whose duty it is to verify deaths. This ordinance came into force on April 1st.—British Medical Journal.
