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- 



