666 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
pinion motion. In its socket fit the various illuminating apparatus, 
which can he centered by slide pieces provided with screws. Arrange- 
ments for obtaining convergent and parallel light can be inserted. 
The mechanical stage (fig. 72, p. 669) is similar to that of the larger 
model, but has no micrometer measuring arrangement. 
All the special eye-pieces and other accessories of the model No. I. 
can be used with this instrument. 
