ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
105 
power. As the accompanying figures (4 and 5) show, the instrument con- 
sists of a double tube, supported on a stand, consisting of a base-board A 
and two vertical pillars B B'. The objectives are so adapted that the 
lines of vision unite exactly on the object. The true field of vision has, 
with a magnification of 25 diameters, a diameter of 10 mm., the distance 
between the objective and the object being 40 mm. The double tubes 
alter their position in a vertical direction’ by means of the cylinders L, 
Fig. 5. 
which work in the tubes G, and they are balanced by the weight 0. 
Horizontal and transverse movements are imparted through the cylin- 
ders N N', which are connected with the pieces K K'. Owing to this 
mobility, an object of 17 X 9-5 cm. = 161-5 qcm. can be examined, 
hence the name Perimicroscope. The instrument is adapted to the 
examiner’s eyes, or rather, the distance between two pupils, by pulling 
out the oculars until a single image is seen. The instrument is 
focused with one hand, and owing to its mobility, obliquely lying 
surfaces can be examined. The object to be examined is placed on a 
black, white, or green glass plate placed on the stand A, which will, of 
course, receive a small vessel or any other object-holder. 
Lantern Microscopy.* — The following correspondence has appeared 
on this subject: — “Permit me to say a few words in connection with 
* English Mechanic, liv. (1891) pp. 309-10, 332. 
