520 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
in simplicity and convenience of use to any other. In the plate P 
(figs. 56 and 57), by which the polarizer is connected with the instru- 
ment, is a slide S', which, as soon as the tube II is lowered by the 
pinion T, has the effect of raising the lens C' from the lens C 2 . A pull 
on the arm G is then sufficient to move the lens C' to one side into a 
depression in the plate P, and the polarizer, thus left only provided 
with the lens C 2 , can be again adjusted in height and used for parallel 
light. To change again to convergent light, the tube R is lowered 
and the slide S pushed in, when the two lenses will again be connected 
together by means of the conical piece of the lens-holder C a . To assure 
the correct position of the lens C' in the ring of the slide S, the tube R 
is provided with four slots, in which fit four corresponding projecting 
pieces in the ring. 
Kochs- Wolz Improved Microscope Lamp.* — The modifications 
introduced into the Kochs- Wolz lamp | are declared by Prof. P. 
Schiefferdecker, who describes the improvements, to make it an ideal 
lamp for microscopical purposes. The principal deviation from the 
original consists in a different form and method of illumination. In the 
present lamp a cylinder of zirconium 
is rendered incandescent by the 
combined action of an oxygen and 
coal-gas flame. The essential parts 
are fixed to a stand consisting of a 
heavy base supplied with a grip- 
handle and a vertical upright M S 
(fig. 59), up and down which they 
may be moved by means of a rack- 
work, the milled head of which is 
seen at SS. Within the metal case 
M C is fixed the zirconium cylinder 
L K, against the middle of which 
plays the flame from the burner B. 
The burner is connected with two 
tubes S r and G r, through which 
the coal and oxygen gases pass. 
Both these tubes can be stopped off 
by the cocks S h Gh. The glass 
rod G is fixed in a tube-like pro- 
longation on the front of the metal case M 0, its inner end lying over- 
against the zirconium cylinder, while its outer end, bent to a convenient 
curve, lies underneath the diaphragm of the Microscope. In order to 
intercept any heat or light from the lamp, a blackened screen S ch is 
placed in front, and from the lower end of this a dark cloth T hangs 
down over the glass rod. The correction glasses are cemented on to 
the outer end of the rod. To set the apparatus going the gas-jet is 
turned full on, lighted, and then the oxygen-tap turned on until the 
flame just hisses. When the zirconium is white hot, the tap is turned 
down carefully till the hissing ceases. 
* Zeitschr. f. Wiss. Mikr., vii. (1891) pp. 450-7 (2 figs.), 
f See this Journal, 1889, p. 126. 
Fig. 58. 
