beneath the surface of the Earth. oa 
the city of ‘Tours in the basin of the Loire.* The spring ceasing 
to flow so freely, it became necessary to draw out the tube to within 
twelve feet of the surface. Immediately the water gushed out one 
third more plentifully, and continued so for several hours, carrying 
with it a large quantity of fine sand, and many remains of plants and 
shells. Among these were twigs of several inches in length blacken- 
ed by the action of the water; fresh stems and roots of marsh plants, 
—of one species in particular so fresh, that they could not have lain 
more than three or four months in the water ; seeds of five or six dif- 
ferent species; and fresh water and land shells, (Planorbis margi- 
natus, Helix:rotundata and striata.) All these are such remains as 
are found after a flood on the banks of small streams. 
The water in this remarkable case, therefore, must proceed’ from 
some subterranean stream, the source of which is to be sought for at 
a distance among the higher grounds of Auvergne and Vivarais, and 
from the temperature of such sources, it is evident we can infer 
— regarding the interor temperature of the earth. 
_ 'M. Magnus} has made some observations on the a ofa 
boring at Rudensdorf, about five German miles from - which 
seem entitled to some confidence. It passes through jietiestiones, gyp- 
sum, and sandstone, alternating with clay-slate, to a depth of sixty five 
English feet. "The mean temperature of the place on which no ex- 
periments have been made is assumed to differ very little from that of 
Berlin, 49.1° F., and the results are as follows: 
Temper. Diff. from mean. For 1° F. 
At 675 feet 67.66 +18.56 36.3 feet. 
516 63.95 414.85 34.7 
392 62.82 13.72 28.5 
The first of these results is the only one to which we can Jook for 
any approximation to the truth. And it comes very near 36.81, the 
result of Kupffer. The other determinations, however, are not with- 
out their valye, they all indicate a more rapid increase of temp 
than the truth, as we should naturally expect. For though the water 
‘as it gushes from the bottom of the tube must undergo considerable 
cooling on its way to the surface, yet it must still retain a considerable 
excess over the temperature of the strata through which it passes, and 
thus indicate a less distance for each degree of the thermometer, as 
* Pogg. Ann. xxi. p. 353 1 Pog. Ann. xxii. p. 146. 
Vou. XXIIT—No. 1. 
