106 Tue Microscope. 
cient for all modern objectives of the largest angular aperture. 
The light is concentrated to practically one point, where it is 
sufficiently strong to give good illumination with the highest 
amplification, but its intensity may be decreased by proper 
stops or the light may be distributed over quite a space by vary- 
ing the distance from the slide. It may be used both dry and 
with the various immersion fluids. 
We furnish it with two styles of mountings, with which the 
same results may be gained as with almost all the various sub- 
stage illuminating apparatus. 
No. 2 consists of the substage adapter and condenser with 
a swinging diaphragm ring between them. This ring receives 
the various stops. and these latter may be changed without dis- 
turbing the condenser—diaphragms with various sizes of cen- 
tral stops are furnished, which give dark ground illumination, 
others which cut off peripheral rays, to decrease the amount of 
light, and still others with circular openings placed at different 
distances from the center, to give different degrees of obliquity. 
A stop is provided for the diaphragm ring when it is in central 
position. 
No. 1 is intended to give the different degrees of oblique 
illumination, from central to that of the utmost possible limit. 
It is provided with a circular opening, +inch in diameter, which 
may be decreased if desired, and which is caused to move 
slowly from center to the edge of the mounting by turning the 
outside milled edge. 
Both of these mountings are adapted to substages attached 
either to the substage bar or fixed to the bottom of the stave. 
The condenser is also furnished with plain substage adapter 
only. 
