ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 



659 



movement of 2 in. gradated to millimetres, vernier reading to • 1 mm. 

 It is fitted with an Abbe stage condenser with iris diaphragm, and a 

 high power dark-ground illuminator. The entire apparatus can be 

 folded up into an exceedingly small space, and is packed in a leather 

 case measuring 11 by 4|^ by 5 in. 



(2) Eye-pieces and Objectives. 



Double Fluorite Objective.* — The firm of E. Leitz has recently 

 introduced a double fluorite objective, a dry 1/8 (3 mm. focal length). 

 Numerical aperture = 0"95. 



(3) Illuminating' and other Apparatus. 



"Rystos" Microscope Platform. f — This platform (fig. 130), made 

 for use with science lanterns, is adjustable so that any ordinary Micro- 

 scope without the draw-tube can be used for projection work ; it can be 



Fig. 130. 



raised or lowered in order that the optical centre of the Microscope may 

 coincide with that of the lantern. 



C. Baker's Miniature Arc Lamp. — This lamp (fig. 131), made at the 

 suggestion of Mr. J. E. Barnard, differs somewhat in design from any 

 other of this type. The hand-feed mechanism is carried on an open 

 frame so that the lamp keeps much cooler when burning than those 

 which are closed in. The carbons are held in V-shape blocks, and are 

 controlled by one milled head made of non-conducting fibre which actu- 

 ates two screws attached to these blocks. By suitable gear wheels the 

 speed at which the carbons are fed is so arranged that the difference in 

 consumption of each carbon is compensated for. 



The lamp is primarily intended for a current of 4 to 5 amperes, but 

 owing to the construction mentioned it may be used for heavier currents 

 up to 8 or 9 amperes. 



* Leitz Catalogue 44a, p. 19. 



t Reynolds and Branson Catalogue, 1912. 



2 Y 2 



