The little camera, with double holder telescopic support for wheel and the case, will weigh about two pounds, which may be carried by means of a strap on the shoulder, or may be buckled to the saddle of the machine.
The detective camera, also, is quite well suited for such a purpose, with the roll-holders or otherwise, as may be desired; but the paper films are more sensitive than the plate, and are, therefore, more suitable for such rapid work as may be required.
PHOTO MICROGRAPHY.
If you place any natural object at a distance from a convex lens, a much smaller image of the same will appear at the focus of the lens. When this small image is reduced to that point that it cannot be seen clearly with the naked eye, and is photographed, it may be called a micro-photograph. On the contrary, if the object is a microscopic one, and is placed at a point very near a convex lens, an enlarged image may be found at a considerable distance from the lens. A photograph of this enlarged image of a microscopic prepared object, is termed a photo-micrograph. p225
Some confusion among so-called authorities on this subject renders their definition of sufficient importance to be given in this connection.
With the former we have nothing to do, as there can be very little interest attaching to the production of pictures of any object on so small a scale as to require a microscope to look at them.
With the latter, however, it is otherwise, for by the aid of photo-micrography we are enabled to place in permanency for closer study those enlargements of natural objects that are revealed to the human eye by the microscope. The secrets of the composition of the drop of water and a knowledge of its "monstrous and terrific inhabitants," are thus made known.
Previous to the introduction of the sensitive dry plate the practice of photo-micrography was confined almost wholly to those possessed of leisure, and ample means to provide the expensive and complicated instruments necessary, or to savants like Dr. Woodward, backed by the resources of a liberal government supplying apparatus and appliances far beyond the means of the ordinary student of natural science.
The advent of the gelatine dry plate placed the workers in this branch of scientific research more nearly on a level, at least as far as the possession of suitable and efficient instruments are concerned, and one of these workers has published for the instruction of amateurs and others a very valuable article on photo-micrography, from which we extract by permission a description of the instruments necessary to the successful practice of this interesting study.
Mr. Walmsley, in the article referred to, says: I will now describe the apparatus I am using at present, p226 passing unnoticed the various stages by which its comparative perfection has been reached. Four essential parts make up the complete outfit.