240 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



effected by means of a helical rackwork and pinion of a new design, 



and the fine adjustment by the rotation of a direct-acting screw. The 



stage and body are of brass, and the height of the instrument when 



placed vertically is lOf in. All the fittings are of the universal size, 



and compensating screws enabling the working parts to be adjusted are 



provided (fig. 28). 



Hitchcock, R. — The ideal projecting Microscope. 



Joum. New York Micr. Soc. Annual, 1902 (1904) pp. 19-23. 



(3) Illuminating' and other Apparatus. 



•?v-Heele's Heliostats.* — These are shown in the accompanying illus- 

 trations. Fig. 29 is of Silbermann's construction with accurate clock- 



Fig. 29. 

 * Catalogue, pp. 21-3, Nos. 83-6. 



