284 SrOIlTART OF CURRENT RESEARCHES RELATING TO 



excellent results ; perfect rosettes cf crystals can be readily obtained, 

 giving brilliant effects with polarized light. 



Bausch and Lomb Turntable. — We have no description of this 

 turntable, but so far as we can gather from the drawing (Fig. 59), it 



Fig. 59. 



differs from other turntables in being provided with a hand rest, 

 which can be adjusted to any convenient height. 



Griffith Cell.*— Mr. E. H. Griffith places the slide on a turntable, 

 and with white-zinc cement turns a circle on the centre if for a 

 transparent mount, or a disk if for an opaque one, then centres to the 

 circle or to the disk a common curtain ring, and immediately paints 

 the ring with the cement, taking care not to push it from its position. 

 When dry, the cement will hold the ring very firmly, so that there 

 need be no fear that it will break off. 



If a shallow cell is desired the rings may be flattened easily ; or 

 if a deep one is required, several rings may be securely fastened one 

 above the other by painting each one in succession. If the cement 

 does not flow readily add benzole; and in case the cell becomes 

 rough, dip the brush in clear benzole and smooth it. Use a brush 

 well filled with the cement to secure a smooth background. With 

 a little practice a person may easily make fifty beautiful and practical 

 white cells in one evening, and in a few hours they will be hard and 

 ready for use. When the cover-glass is to be fastened, a little of the 



* Amer. Mon. Micr. Journ., iii. (1882) p. 9. 



