ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 



349 



permit the use of the observing prism and vertical illuminator at the 

 same time. This is especially provided for in Stand No. 1154 (fig. 57), 

 which has coarse and fine adjustments, inclination joint, and stage with 

 mechanical motion in both directions. Rack-and -pinion adjustments 

 are provided for raising and lowering the stage. The snbstage has rack- 

 and-pinion focussing and centring adjustments. The same firm adapt 

 their " Imperial " Microscopes for metallurgy by providing an adjust- 

 ment for racking down the whole stage a distance of 2 in. u 



Fig. 58. 



Bausch and Lomb's Continental Microscope, BB Model. — This 

 instrument, which was exhibited and described by Mr. Rousselet at the 

 March meeting (see p. 244), is shown in fig. 58. 



(3) Illuminating' and other Apparatus. 



Koristka's Large Reflecting Mirror. * — This adjunct, which is 

 shown in fig. 59, is intended to be used as a heliostat. It is then fixed 

 outside the shutter of a dark room and the plane of the mirror so turned 

 as to reflect the light through the tubular mount into the room. The 

 screw-heads allow the slope of the plane to be corrected, from time to 



* F. Koristka's Catalogue, Milan, fig. 65, p. 77. This mirror was originally 

 invented by John Cuff, of Fleet Street, in 1743. 



June 17 th, 1903 2 a 



