Appendix B.
MICRO-PHOTOGRAPHY.
Owing in some measure to the more complete knowledge of the subject gained by the experience of years, and the extreme value of micro-photography in the delineation of bacteria, and perhaps in a measure to the advent of the perfected dry-plate process, photography is being rapidly pressed forward in conjunction with the microscope. In the course of the year [1898] no less than six, more or less, new forms of micro-photographic apparatus have appeared; two are simple, one for daylight, one for lamp, one for electric, and one for lime-light illumination. Passing over the simpler forms, for a notice of which I am unable to find room, there is one piece of new apparatus, that of Mr. E. B. Stringer, which is not only new, but is in every way adapted to the work of micro-photography. It is in fact a well-arranged camera, fitted with a powerful condensing arrangement, each portion of which is capable of being independently centred and controlled. Indeed, the specially interesting feature of the apparatus is the control of the gas and the beautiful and uniformally illuminating disc of zircon, about a quarter of an inch in diameter.
Fig. 446.—Mr. E. B. Stringer’s Improved Micro-photography Apparatus.
B. Oxyhydrogen jet with zirconium cylinder, covered by the cowl A when working.
C. Doublet parallelising condenser, with centering screws.
D. Iris diaphragm.
E. Holder for trough and light-filtering media.
F. Plano-convex lens, 41⁄4ins. diameter, with centering screws G
H. Plano-concave lens, with iris diaphragm T.
K. Connecting pulleys between focussing rod of camera and fine adjustment of Microscope.
L. Triangular frame in which Microscope feet are placed.
M. Flap shutter.
N. Door through which image is observed on card screen, etc.
O. Solid block of mahogany on which camera body is fixed and supported.
P. Dark slide.
This efficient photo-micrographic apparatus ([Fig. 446]) is made by Messrs. W. Watson & Sons, under the instructions of Mr. E. B. Stringer. The illuminating condensing system is mounted on a square brass bar, the illuminant being oxygen-hydrogen light burning on zirconium. Immediately in front of this is a condenser, c, four and a half inches diameter, with an iris diaphragm, D, immediately in front of it. The holder, E, carries the light filtering media through which the beam passes and enters the condenser, F. It then goes through a tank of water contained in the cone, F to H, and emerges a practically parallel beam of great intensity through a plano-concave lens, h, of such a diameter as to exactly fill the back lens of the substage condenser. There is an iris diaphragm, T, for cutting off stray light.
The whole of the apparatus is fitted with centring screws and clamps, and after having been once adjusted it is ready for use at any moment without preparation. By means of this apparatus, instantaneous pictures can be taken of living rotifers, so brilliant is the illumination, while photographs of such fine objects as the flagella of bacteria cannot be secured with the same amount of certainty by any other microphotographic apparatus with which I have made myself acquainted.