( 404 ) 
USEFUL PROJECTS. 
Experiments on the Causes of the 
Warmth of warm Clothing, by 
Major General Sir Benjamin 
Thompson, Knt. F R.S. 
Extracted from the Philosophical 
Transactions, Part I, Page 60. 
AVING found that the fine- 
ness and equal distribution 
of a body or substance made use of 
to form a covering to confine heat, 
contributes so much to the warmth 
of the covering, I was desirous to 
see the effect’ of condensing the 
covering, its quantity of matter re- 
maining the same, but its thick- 
ness being diminished in propor- 
tion to the increase of its density. 
The experiment I made for this 
purpose was as follows:—I took 
sixteen grains of common sewing- 
silk, neither very fine nor very 
coarse, and winding it about the 
bulb of the thermometer in such a 
manner that it entirely covered it, 
and was as nearly as possible of the 
same thickness in every part, 1 re- 
placed the thermometer in its cy- 
linder and globe, and heating it in 
boiling water, cooled it in ice and 
water. The results of the experi- 
ment were as may be seen in the 
following table; and in order that 
it may be compared with those 
made with the same quantity of 
silk differently disposed of, I have 
placed those experiments by the 
side of it. 
5 “= ~ oS 
re c. 7 5 =. oe 
LY) a. we i a5 2 =~ 
3 = fo | ape |5ea8 
= af ae: aoe | w22e 
E 3 fil Bes Veece 
es z a een | ghee 
Pe = ate) =3s 
Exp. No. 4./Exp. No.14.)Exp. No.15.|Exp. No.19. 
70° _ —_ — _ 
60° gi" 90” 67" 46" 
50° 110 106 79 62 
40° 133 128 99 85 
30° 185 172 135 121 
20° 273 246 195 191 
10° 489 427 342 399 
Total times| 1284 1169 917 904 
It 
