606 
JJR. J. T. BOTTOMLEY ON THEBMAL 
cation of this paper. The operation of soldering up the enclosure so thoroughly as to 
withstand the high temperature required for heating up the hanging globe and to 
remain perfectly air-tight for the Sprengel pump was at all times difficult. But 
when the enclosure contained the silvered globe, in the highest state of polish, it 
became almost impossible to perform the operation without tarnishing the globe. 
The experiment of April 14 was satisfactory, except for the somewhat variable state 
of the vacuum ; which was, however, very high throughout. The numbers quoted 
show the eflect of this variableness. A new experiment was tried on April 17 ; but 
the result was less satisfactory; the globe turned out to be tarnished when the 
enclosure was opened ; and the rapidity of loss of heat corresponds. 
Unfortunately, the time at which these experiments were tried was the very end 
of the Glasgow winter session. Indeed at this time I had already become involved 
in the heavy University work belonging to this period of the year. Before we could 
resume experimenting, my friend Mr. Tanakadate was obliged to leave Glasgow for 
Berlin ; and I have not since then found the time and circumstances necessary for 
repeating these last experiments with an enclosure slightly modified to make the 
soldering more easy and more sure. 
Table II.—Copper globe sooted. (Apparatus fig. 1.) 
October 22, 1889. Vacuum. 
Pressure M.* 
Temperature of bath surrounding enclosure, 
17°-5 0. 
October 24, 1889. Air. 
Pressure 75 centims. 
Temperature of bath surrounding enclosure, ' 
16°-4 C. 
Excess of temperature 
of globe above tempera¬ 
ture of surroundings. 
Loss of heat per sq. 
centini. per second 
per 1° C. of excess. 
Excess of temj^erature 
of globe above tempera- 
tui’e of surroundings. 
Loss of heat per sq. 1 
centim. per second 
per 1° C. of excess. 
7y'G 
1-37 X 10-1 
O 
72-1 
2-76 X 10--1 
74-0 
1-36 „ 
62-3 
2-69 „ ' 
08-9 
1-34 „ 
54-1 
2-62 
64-2 
P32 
47-2 
2-55 
69-9 
1-30 
41-3 
2-48 
5o'9 
1-29 
36-2 
2-41 
52-2 
1-27 
31-9 
2-34 
48-8 
1-25 
28-2 
2-27 
45-7 
1-23 
25-1 
2-20 
42-8 
1-22 
22-4 
213 
40-1 
1-20 
20-0 
2-06 
37-7 
1-18 
18-0 
1-99 
36'4 
1T6 
16-2 
1-92 
31-3 
1T3 
27-8 
1-09 
24-8 
1-06 
22-2 
1-02 
20-0 
0-989 
18-0 
0-954 
1 
1 
M clsnotcs a pi6Sh>urG equal to (uic-iuillioiith of au atiuospliere. H'lie lucasurenieut, towevci', is not 
of the TOTAL pressure in the enclosure; but only of the pressure of the gas not collapsible in the MacLeod 
gauge. 
