232 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
A camera, as will be seen from tbe fig., slides over tbe top of the 
body-tube. The tripod feet of the Microscope are provided with levelling 
screws, while the movements of the stage are effected by a White lever, 
which is made of extra length so that it may be close to the milled 
heads of the coarse-adjustment. A special support for the lever is attached 
to the cross-arm. A small electric incandescent lamp is attached 
beneath the stage. 
The small fig. on the left is the focusing glass (shown in position 
by dotted lines on the top of the camera). The fig. on the right is the 
ground-glass plate, which is divided into spaces. 
The instrument is also made with the photographic part independent, 
and mounted on a slide fitting, supported by a strong cast-iron base.* 
Lehmann’s Microscope for heating objects at definite tempera- 
tures, j* — Dr. O. Lehmann has found the Microscope shown in figs. 17 
and 18 very serviceable where it is desired to heat an object at definite 
temperatures, a regular stream of hot liquid being kept up through the 
vessel containing the preparation by means of a pump. Dr. Lehmann 
Fig. 17. 
first made use of an ordinary air-pump, in combination with a spacious 
reservoir, which was put in motion by a gas motor, but in the later form 
a centrifugal pump is used, as represented (somewhat diagrammatically) 
in fig. 17. A is the Microscope, whose stand is fastened to the wall in 
order to avoid oscillations due to the action of the pump ; B is the 
reservoir for the liquid, and C the centrifugal pump. Out of the 
reservoir B, in which equal distribution of temperature is effected by 
* Cf. La Lumiere Electrique, xix. (1886) pp. 217-9 (2 figs.). 
t ‘ Molekularphysik,’ Band i. (1888) pp. 151-2 (2 figs.). 
