ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
337 
other with steel-blue glass. The cylindrical reservoir is 2 in. diameter, 
and the total height of the lamp is 7 in. A blotting-paper wick is used. 
Simple Instrument for Inclining a Preparation in the Micro- 
scope.* — Mr. T. A. Jagger, jun., has devised an instrument for use in 
petrography, especially in connection with the optical methods of 
Michel-Levy and Fedorow for the determination of felspars ; it will 
also be of use in cases where it is necessary to examine the edges of 
objects in reflected light. The object-holder clip is supported by a 
ball-and-socket joint on a foot-plate, which may be fitted to the stage 
of the Microscope. This allows the object to be turned into any 
desired azimuth, and the various minerals in rock sections can then be 
brought into definite orientations, as is done in the more complicated 
“ universal stage ” of Fedorow. The optic figures seen in convergent 
polarised light may also be brought into the centre of the field of view. 
Modification of the Automatic Gas-Stop for Extinguishing the 
Burner of Incubators.f — Dr. B. Schiirmayer has devised a modification 
of the gas-stop to incubators which prevents the escape of gas and the 
danger of its exploding. The supply tube is fitted with a metal spiral 
lever which acts on a stopcock, so that if there be any fault in the work- 
ing of the apparatus beyond this point, and the gas supplied to the 
burner fail, the lever acts on the stopcock, and thereby prevents further 
access of gas to the apparatus. The most important feature of the in- 
vention is that all the parts of the apparatus are of metal. 
Slide and Cover-Glass Holders.^ — Herr S. Robertson has devised 
holders for slides and cover-glasses, the construction of which may be 
Fig. 29. 
grasped from an inspection of the illustrations (figs. 29 and 30). The 
former is merely a spring-forceps made of nickelled wire, the inside of 
the fangs being grooved for the reception of the slide. The cover-glass 
* Amer. Journ. Sci., iii. (1897; pp. 129-31 (2 figs.), 
t Centralbl. Bakt. u. Par., l te Abt., xxi. (1897) pp. 400-1 (1 fie.X 
% Tom. cit., pp. 589-91 (2 figs.). 
