temperature of the interior of the earth. 113 



The number of mines subjected to these experiments are 

 more than forty : the number of experiments amount to about 

 three hundred. Many observations of less importance, made 

 not expressly, but accidentally, in mines and caverns of other 

 countries, are omitted. They generally relate to the tempe- 

 rature of the au', and the results are analagous to those made 

 more carefully elsewhere. 



It is necessary to examine with much care experiments in 

 a small way, when we mean to draw conclusions from them 

 affecting the heat of the great mass of the globe. Suppose, 

 for mstance, the error to be one degree in excess for each 

 one hundred metres, (three hundred and twenty-eight feet,) 

 it would cause in the calculation an error of five hundred 

 metres too near the surface in settling the depth at which 

 water boils. 



*'With these precautions in view," says M. Cordier, "1 made 

 experiments for myself, at the mine of Littry^ near Bayeux, De- 

 partment of Calvados, where the shaft opens sixty metres above 

 the ievel of the sea: at the mine of Decise, to the north of the 

 town of that name, in the Department of Nievre, elevated one 

 hundred and fifty metres above the sea : at the mine of Carmeaux^ 

 Department of Tarn, north of Alby, two himdred and fifty me- 

 tres above the level of the sea. These experiments were made 

 in 1822 and 1825, with a mercurial thermometer, carefully com- 

 pared ; and with the aid of M. M. Arago and Matthieu, the de- 

 grees were all reduced to the centigrade division of the standard 

 at the Observatory at Paris. In the present memoir, the centi- 

 grade division has been employed throughout." 



M. Cordier then enters into an elaborate investigation of 

 the sources of error, arising from the circulation of air from 

 the bottom of the mine toward the top ; from the intermix- 

 ture of the external air ; from the changes produced in the air 

 by the infiltration of water into the mine from above ; from 

 the corrections required for the effect of candles, the pre- 

 sence of workmen, and the heat of their bodies and their 



In Peru arid Mexico. Ann. de Chim. et de Phys. torn. 13, p. 207. 



The British experiments may also be found in their philosophical periodicals, 

 for these twelve or fifteen years past. Some are more, some are less exact. 

 Most of them liable to objections, noted by Cordier, in the progress of the 

 present memoir ; but all tending to the same conclusion, that the globe of our 

 earth, under the crust forming its surface, has always bem, and novo is, in 

 a state of igneous fusion. 



Vol. XV,— No, 1. 15 



