Photographic Enlargement of Small Solid Objects

IN NATURE of Aug. 18, p. 239, Mr. A. Mallock makes the admirable suggestion that the required magnification should be obtained, not directly, but by ordinary enlargement from a negative showing the object on some lower scale-the intermediate negative being of course taken to such a standard of sharpness as will permit of the subsequent enlargement. This seems to be the only way by which the great difficulties of this kind of work can be overcome. The most troublesome business of all is that of focusing, and this could be entirely eliminated if a simple form of enlarging camera were carefully and permanently registered to give perfect focus on some one fixed intermediate scale, and means were provided for measuring exactly the depth of the object about to be photographed, and for putting the object in its proper position in front of the lens.