et Oe ee 
‘ 
tion of the drum. Each af 
_ With the figures 1, 2, 3 and 15. 
2 Work, it 
ele left half of the drum, a 4, "e: 
-~ in position by the screw, $, and may 
l 
1883.] Microscopy. 1313 
the rod compels the sections to pass between itself and the knife. 
The parallel position of the rod in the vertical plane is obtained 
by rotating it about the axis, x, which turns in the hole c or c'; 
the parallel position in the horizontal plane is reached through 
the screw æ and a’ ; and the vertical distance of the rod from the 
edge of the knife is regulated by the screw, 6. The entire appa- 
ratus is slipped on at the end of the blade, and held fast by two 
springs that press upon the under surface of the blade. The rod 
and its holder, which rotates on the axis, dd, can be lifted up 
from the edge of the knife by the aid of the handle, 7, and turned 
back far enough to admit of cleaning the rod and the knife. The 
apparatus includes three interchangeable rods, differing in thick- 
hess in adaptation to sections of different sizes. 
Tue REGISTERING MICROMETER-SCREW.—In the “ Microscopy” 
So closely opposed that the 
dividing ‘line (dotted in the 
gure) is scarcely visible. The 
Periphery of each half is com- 
Posed of two zones of unequal 
radii. The larger zones, 4 and 
» are in apposition, and to- 
Sether form the graduated por- 
th 
€ smaller zones are marked 
‘hen the drum is in order for 
Fic. 2.—Drum of the new ernest 
be rotated indepen- 
