ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



811 



the lamp is provided for on top of the spherical casing, and the whole is 

 mounted on a china pillar with liase. 



In the cylindrical mount attached to the spherical metal casing an 

 aplanatic condenser of short focus is mounted with a slot arrangement 

 in front to receive ground glass or colour screens. The lamp is fitted 

 to the base in an inclined position, and the aplanatic condenser, which 

 is a fixture, is so arranged that at a comparatively short distance from 

 the lamp an enlarged image of the rod is projected, filling the entire 

 aperture of an average Microscope mirror. The small glass tube 



Fig. 93. 



mounted to base is a wire resistance for the lamp. The lamp burns at 

 1 ampere, and can be supplied suitable for either continuous or alter- 



nating current. 



For high voltage an auxiliary resistance is supplied. 



Winkel's Drawing Microscope.* — This excellent Microscope, says 

 E. M. Nelson, although described nine years ago, is still so little known 

 that a second and more particular account of it is necessary. Until it 

 had been in use, the writer had no idea what a valuable instrument it 

 was. Several naturalists and science masters who have seen it were very 

 much struck with it, and expressed astonishment that it had not come 

 into more general use. 



Fig. 94 shows the instrument by itself — a non-inclinable Microscope 

 upon a horseshoe foot. It is a stage focuser, and the stage, 2*9 in. 

 square, carries on the same bracket a concave mirror 1 "8in. in diameter. 



* English Mechanic, xciv. (1911) pp. 257-8 (3 figs.). 



