1901) | MICROSCOPICAL JOURNAL 169 
to the numerical aperture of the objective is used, the ne- 
cessity for a slow and precise movement by fine ad diste 
ment becomes overwhelmingly apparent. 
In a previous article we referred to the fact that many 
new substage condensers yielding large cones of illumin- 
ation had been recently introduced, and as the supply of 
such articles must indicate a demand, it necessarily fol- 
lows that the people who have used them have discover- 
ed the weakness in the fineadjustments of their instru- 
ments, have called for something better, and response is 
_ being made by manufacturers to meet this fresh demand. 
There are four new fine adjustments which I propose to 
review, as follows :—The Continental pillar fine adjust- 
ment with levers, designed by Reichert, of Vienna; the 
new fine adjustment fitted to their photo-micrographic 
stand, by Zeiss ; the “Ariston,” by Swift and Sons; and 
Stringer’s fine adjustment, by W. Watson and Sons. 
REICHERT’S Fine ADJUSTMENT.—The great weakness of 
the Continental pillar form of fine adjustment has been 
consequent principally on the difficulty of producing a suf- 
ficiently slow rate of movement witha direct-acting screw 
that would stand wear and tear. The problem has been 
met by Reichert’s device, which consists of a screw, hav- 
ing a point which engages two lever arms, the upper 
pressing upon the lower, and being mounted from the out- 
er sides of the pillar. To the under sides of these levers 
is attached a piece of hemispherically shaped metal,which 
has on its curved side a point which communicates the 
motion. A reference to the illustration in his catalogue 
makes this otherwise obscure description quite clear,and 
it will be further seen that the rate of movement is di« 
minished by the proportions of the lever arms, which are 
about 24:1. This would mean that if a screw of the or- 
dinary kind were used, the rate would be reduced to 1- 
250 in. for each revolution instead of 1-100 as in the old 
pattern. 
