+ er a ae ee. ae —— fg 
Of the interior of the e 115 
“1. Setting aside some of them, as bei too ‘uncertain’and inac- 
‘curate — reasoned from, all the ing oo mer in 
degree, a notable increase of temperatur . 
hcg the surface of the earth towards the interior : this couctee 
= may reasonably be allow 
e results nliskted.. at the Observatory of P. ar 
the only ones which enable us with something like saceaitieg to 
dred and twelve feet Engl 
the rs results furnish numerical expres. 
sions sufficiently approximative of the required law, to be o 
use. ‘These expressions vary from fifty-seven to thirteen me- 
tres for one degree (cent.) of increased heat. The mean of 
admitted. ety concurrence of this testimony to the general 
act, is o ght, i testa as they comprise the result of 
eas series as of local observations. 
. In grouping by countries, the results admissible on what- 
ever ain . 1 incline to think,” says Cordier, “that the results 
collected at the same place, depend upon, and are a 
with, not merely the imperfection of the experim ut 
a real irregularity in ag distribution of subterranean eat from 
ry to ernie 
‘¢ The observati as hither published, possess therefore a Teal 
value, efficient att incontestable. But others are still wanti 
and I proceed to give an account of those that I have sade 
myse 
Xe New and direct experiments on subterranean temperature, gy 
M. Cordier.) I preferred coal mines: because the branching 
excavations are carried to a considerable distance from the shaft : 
eC from the ease of working them, the excavations ad- 
vance tou teh and are not so liable to be affected by external 
circumstances use it ise to make speedily and with 
great ease, deep holes in these mines: in which the tempera- 
ture can be ascertained free from opposing circumstances 
bulbs of the thermometers in these experiments were enveloped 
in seven folds of si ; so, however, as t it the de- 
gree on the scale to be easily come at. They were kept in a 
tin case. They were so constructed, that being immersed in 
melting i re they took but twelve minutes to descen m 15° 
cent. to 5 decimetres in a mass of -givaag sand, in 
a cellar the ey took twenty minutes to arrive at the temperature 
of the cellar, losing eight degrees of their initial tinmperasae 
