1819.] and on the Laws of the Communication of Heat. 333 
Total velocities of|/Total velocities of 
Excesses of temp. cooling of the naked|couling of the sil-) Values of V. 
of thermometer. 
bulb. vered bulb. 
260° 24-42° 10-96° 810° 
240 21°12 9°82 TAL 
220 17:92 8°59 6°61 
200 15°30 TRAY 5:92 
180 13°04 6°57 519 
160 10°70 5°59 4-50 
140 8°75 4-61 3°73 
120 6°82 3°80 Pash | 
100 567 3°06 2°53 
80 4:15 2°32 1:93 
The second and third columns contain the total velocities of 
cooling of a thermometer with a naked and silver bulb for the 
excesses of temperature contained in the first column. _ The last 
column contains the corresponding values of v; that is to say, 
the losses of heat, which the contact of air alone produces in 
both thermometers. But the law which these losses of heat 
follow is expressed by the following equation : 
by ie 
in which n must be determined in each particular case ; for the 
one which we are considering x = 0°00857. By giving suc- 
_ cessively to ¢ all the values for every 20°, from 80° to 260°, 
we shall have the corresponding values of v, which will differ 
but little from those deduced experimentally. To make this 
comparison more easy, we have united in the following table 
the observed and calculated values of v. 
Excesses of temp. Observed values of V. Calculated values of Y. 
eae. class ech hie LIE nies Hhadsiac met nina 8-14° 
on! UR, SRE is a a eae 1 8 7°38 
ED Ce Naiowccip S's w/asa'a wh a, Oy Riera Mere janie: Claes 
BU nee Sex ats arabes ial ERE 2: RU A RN De ys 5°87 
Oiler ges Rete era Ae ED ON ae oe AP, Mee 5:17 
BY | sste coreg ota vee 236) Ree PAS. .. 447 
OR Re Be tet ea ONS! © raid sua blcaaioyn, s\n 3°79 
glee bby Stink dips SE oe ee mache siaie 3°14 
Ere ils pope DAS «Ns, abla neki aleisinh ols 2°50 
ne et or De GRE) ns, ohne ania ers ee 1:90 
Thus the losses of heat by air are confirmed when we extend 
our observations to greater excesses of temperature, The results 
already stated will likewise furnish us with the means of verify- 
ing the law of cooling in vacuo. It is sufficient for that to 
subtract from the total velocities of cooling those which are 
due to the sole contact of air; that is to say, the successive 
