Optical projection: a treatise on the use of the lantern in exhibition and scientific demonstration (1906)

APPENDIX 435 A lantern for laboratory work of very great usefulness, though more expensive than the preceding instrument, is shown in fig. 246. As will be seen from the illustration, it is practically a combine 1 lantern and optical bench; the body is of ribbed aluminium, and the various optical parts slide on an accurately planed lathe-bed base, thus ensuring exact centring. This base makes a very rigid support for a microscope, polariscope, or other optical instrument. The lantern, however, from its nature is not very portable. Another science lantern deserving of mention, though its size and FIG. 246.—Lathe-Bed Lantern price render it almost prohibitive, is Messrs. Zeiss's ' Epidiascope.' This is a powerful instrument for direct, vertical, opaque, or microscopic work. Any opaque object up to nearly a foot square can be easily shown, the current required being 40 to 50 amperes. Instruments of this size and price, however, are only likely to be /required in very large institutions. Other firms are also experimenting with somewhat similar apparatus, so that shortly it is probable there will be choice of patterns in these expensive instruments. Colour Photography. —Examples of nearly all methods of photography in natural colours are now obtainable as lantern-