288 Mr. Walker's Observations on the 
holding two pints ; b, the tube, holding five ounces, which, 
together with the lid c, forms a cover to take off and on the 
vessel. 
N. B. This vessel may, if preferred,* be used instead of fig. 1. 
the parts corresponding with it, except in not being open 
at bottom, and the continuation of the tube upwards just suf- 
ficient to serve for a handle. 
Fig. 3. is a vessel in one piece, open at the bottom, hold- 
ing when inverted two pints ; b, the tube, holding four ounces 
and a half. 
Fig. 4. a vessel open at bottom, holding inverted one pint. 
Fig. 5. a cover to fig. 4. a, a, the body, fitting exactly over, 
and b the cup-part (holding three ounces), fitting exactly 
within, the corresponding parts of fig. 4. 
Fig. 6 . the instrument for grinding the ice into powder ; 
it works upon a short centre point, and has the edge bevilled 
contrary ways on each side the point, so as to follow. The 
fineness of the powder is regulated by the degree of pressure 
used. The handle is wood, the rest metal : a, is a sliding co- 
ver, fitting on the tube in which the ice is ground, to exclude 
the external air, and to keep the instrument steady ; b, is the 
shoulder or guard, to prevent the point of the instrument 
from touching, so as to endanger injuring' the bottom of the 
tube. It should be made so as to fit, without grating the in- 
side of the tube in using. 
The tubes of each of the vessels should be somewhat shorter 
than the vessel, so as not quite to reach the bottom of it. 
Fig. 7. a thermometer glass, with the bulb three-fourths 
full of quicksilver. 
