126 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



stands with substagcs,* sbowu in figs. 15 and IG (for 1'40 N.A.). 

 Here the condenser slides into the substage, and can be accurately 

 centered by the substage adjusting screws. It is, however, very heavy. 



Fig. 15. 



Fig. 16. 



Swift's Cone and Achromatized Immersion Paraboloid Con- 

 denser. — Mr. J. Swift, referring to Dr. Wallich's condenser described 



Fig. 17. 



Fig. 18. 



at p. 963 of Vol. IV. of this Journal, claims priority in the construc- 

 tion of such a condenser, and sends us the diagram, fig. 17, of the 



* See also this Journal, ii. (1882) p. 411. 



