Zi3 On Heat £? Cold produced ly Mechanical

thermometer seemed very well to accord withthe supposition of great heat or cold acting uponit for a few seconds only.

EXPERIMENT a.

Pursuing this idea I imagined that if twothermometers whose bulbs were very unequal inmagnitude were inclosed together, the smallerbulb ought to give the greater variation : ac-cordingly I inclosed two, the diameters of theirbulbs being .35 and .65 of an inch respectively ;and having exhausted the air and restored itagain repeatedly in succession, and found amean of the variations, that of the small bulbwas 2 0 . 8, and that of the large, 2°. 2.

EXPERIMENT 3.

Repeated the exhaustion with the small ther-mometer inclosed in three different circum-stances successively; tst with the bulb in thecentre of the receiver; 2d with the bulb restingon' the wet leather of the plate; and 3d with thebulb resting against the side of the receiver.

ist Case—Reduced by exhaustion .2°.45

2d Case—.2 .15

3d Case— .1 .2

ist Case—Raised by restoring the air .4 .05

sd Case—...2 .25

gd Case— ......-.2 .8