USEFUL P 
It is not alittle remarkable, that, 
though the covering formed of sew- 
ing silk wound round the bulb of the 
thermometer in the 19th expe- 
riment, appeared to have so little 
power of confining the heat when the 
instrument was very hot, or when it 
was first plunged into. the ice and 
water, yet afterwards, when the heat 
of the thermometer approached much 
nearer to that of the surrounding 
medium, its power of confining the 
heat which remained in the bulb of 
the thermometer, appeared to be 
even greater than that of the silk 
in the experiment No. 15, the time 
of cooling from 20° to 10° being 
in the one 399", and in the other 
342”. The same appearance was 
observed in the following expe- 
riment, in which the bulb of the 
thermometer was surrounded by 
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my 00 tl! 79" 83” | 45” | 80” 42" 
50° 95 63 95 60 93 62 56 
4u° | 118 89 | 117 83 | 115 83 74 
80° | 162 126 152 115 150 117 108 
90° | 93g | 200 | 221 | 179 | 218 | 180 | 168 
“ 10° | 4296 | 410 | 378 | 370 | 376 | 385 | 338 
tec 1118 | 934 |1046 | 852 |1032 | 873 | 783 
Cc3. 
Exp. 5, |Exp. 20.| Exp.6. |Exp. 21.) Exp.7. Exp. 22./Exp 23 
ROJECTS. 
threads of wool, of cotton, and of 
linen, or flax, wound round it in 
the like manner as the sewing-silk 
was wound round it in the last ex- 
periment. 
The following table shows the 
results of these experiments, with 
the threads of various kinds; and, 
that they may the more easily be 
compared with those made with 
the same quantity of the sane sub- 
stance ina different form, I have 
placed the accounts of these ex- 
periments by the side of each other. 
I have also added the account of 
an experiment, in which sixteen 
grains of fine linen cloth were 
wrapped round the bulb of the 
thermometer, going round it nine 
times, and being bound together at 
the top and bottom of it, so as 
completely to cover it. bY 
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That 
