114 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



The first is the introduction into the body-tube of a second analyser c, 

 which is sujiported on a hinged arm so that it can be rapidly inserted 



Fig. 5. 



and removed. This arrangement was adopted by M. Nachet for the 

 Microscope which we described in 1881.* 



* See this Journal, 1881, p. 934. 



