410 Miscellanies. 



The author considers the preceding inferences as a legitimate in- 

 duction from the observed and recorded facts ; and proceeds to sug- 

 gest an explanation of the gradual sinking and subsequent elevation 

 of the ground on which the temple stands. From some experi- 

 ments of Col. Totten, Am. Jour. Sci. and Arts, Vol. xxii, p. 136, 

 he has calculated a table of the expansion in feet, and decimal parts 

 of granite, marble, and sandstone, of various thicknesses from one 

 to five hundred miles, and produced by variations of temperature of 

 1°, 20°, 50°, 100°, 500°, of Fahrenheit— and he finds from this 

 table, that if the strata below the temple expand equally with sand- 

 stone, and a thickness of five miles were to receive an accession of 

 heat equal only to 500°, the temple would be raised twenty five 

 feet — 'a greater alteration of leve.l than is required to account for the 

 phenomena In question. An additional temperature of 50° would 

 produce the same effect upon a thickness of ten miles, and an addi- 

 tion of 500° would produce it on a bed only a single mile in thick- 

 ness. 



Mr. Babbage then adverts to the various sources of volcanic heat 

 in the immediate neighborhood ; he conceives that the change 

 of level may be accounted for by supposing the temple to have been 

 built upon the surface of matter at a high temperature, which subse- 

 quently contracted by slowly cooling down, that when this contraction 

 had reached a certain point, a fresh accession of heat from some 

 neighboring volcano, by raising the temperature of the beds again 

 produced a renewed expansion, and which restored the temple to its 

 present; level. The periods at which these events happened are 

 then compared with various historical records. 



The second part of this letter contains some views respecting the 

 possible action of existing causes, in elevating continents and moun- 

 tain-ranges — w hich occurred to the- author in reflecting on the pre- 

 ceding explanation. He assumes, as the basis of this reasoning, 

 the following estabhshed facts. 



1. That as we descend below the surface of the earth at any 

 point, the temperature increases. 



2. That solid rocks expand by being heated ; but that clay and 

 some other substances contract under the same circumstances. 



3. That different rocks and strata conduct heat differently. 



4. That the earth radiates heat differently, or at different points 

 of its surface, according as it is covered with forests, with mountains, 

 with deserts, or with water. 



