98 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Watson's "Simplex" Dissecting Microscope.*— This stand (fig. 10) 

 is adapted for the firm's aplanatic magnifiers mounted for dissecting. 

 For focusing it is supplied with a spiral-screw adjustment, and it is 



Fig. 10. 



fitted with a glass disk for stage, a plane mirror and matt opal reflector, 

 and hand-rests. 



03) Eye-pieces and Objectives. 



Bifocal or Multifocal Lenses.f — Under the title of " An Interesting 

 Lens " the English Mechanic describes an improved method of manu- 

 facturing bifocal lenses. It will be seen that the method may be applied 

 to multifocal lenses. The process consists in so uniting two or more 

 bodies of glass, differing in index or kind, while both bodies are in a 

 molten state, and in so shaping the united bodies, while molten or 

 plastic, that bifocal, achromatic, and compound or toric lenses can be 

 produced by simple grinding. By uniting white and coloured glasses of 

 tie same or different indices a lens may be produced having a coloured 

 and a clear portion. By joining the different kinds of glass in such a 

 manner while both are in a molten state the blank, from which the 

 tinished lens will be subsequently formed, may be blown, pressed, rolled, 

 or otherwise shaped into spherical, cylindrical, or curved shapes, as may 



* Watson and Sons, Ltd., Catalogue 1909, p. 70 (1 fig.). 



t English Mechanic, lxxxviii. (Nov. 20, 1908) pp. 367-8 (6 figs.) 



