ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
605 
L 2 are for the admission of air. The tube L of the arm A is in con- 
nection with a reservoir of compressed air, which effects a quick cooling 
when necessary. 
To connect this apparatus with a Microscope, the lower part of the 
screw-piece fits into the aperture of 
the Microscope-stage, so that the 
stage can he rotated while the arm 
A with the tubes remains fixed. 
For heating up to 360° a drum 
(fig. 7 6), which carries a thermometer 
and the preparation, is added to the 
apparatus. This consists of two 
parts T and T x . The lower part T, 
carrying the thermometer, is con- 
nected with the stage B by a screw 
K, while the upper part T! can be 
turned to one side about the axis N 
by means of the lever H. The 
preparation is placed on a ring in 
the drum, and is kept at the same 
height as the thermometer. 
The apparatus was exhibited at 
the Exhibition of the Heidelberg 
Naturforscher - Versammlung, and 
has been described in the ‘ Ab- 
theilung fiir Instrumentenkunde.’* 
It has already met with considerable 
success and is particularly suitable 
for mineralogical-petrographical in- 
vestigations. 
Bolting Gauze.f — Mr. Charles 
M. Yorce writes that he has “done 
no microscopical work lately that 
has any novelty in it, unless it may 
be the measurement of an assortment 
of bolting gauze and other goods 
used for sieves, to ascertain the 
average and maximum sizes of the 
particles which pass through the same, and the relation of such size to 
the rating of the goods which is always by the number of meshes to the 
inch or centimeter. Bolting gauze of ‘ 200 meshes to the inch ’ will not 
pass particles of approximately globular form larger than about 1/400 
in., and the average size of the particles passed will be considerably 
less, about 1/450.” 
A Simple Turn-table.:]: — Mr. A. S. Elliott describes a simple turn- 
table. “ Procure the frame and running gear of any cheap clock. Fifty 
cents will cover cost of all materials. Remove the main spring from its 
place and make the wheel carrying it firm on the shaft. Remove all 
* Cf. Zeitschr. f. Instrumentenk., 1889, pp. 359 and 478. 
f Amer. Mon. Micr. Journ., xi. (1890) p. 106. X T. c., p. 117. 
