222 Notice of some Recent 



little from zero, in place of being, as lias been generally 

 calculated below the temperature of the coldest regions of 

 the globe. The variations in the temperature of space 

 may, however, be very considerable, and they ought to pro- 

 duce corresponding variations in that of the earth, which 

 will extend to depths dependant on their extent and degree. 

 " If we suppose for example, a block of stone to be carried 

 from the equator to our latitudes, its cooling will have com- 

 menced at the surface and extended into the interior, and 

 if it has not reached the whole mass because the period has 

 been insufficient ; this body when it has arrived in our cli- 

 mate will present the phenomenon of a temperature increas- 

 ing from the surface. The earth is in the condition of this 

 block of stone ; it is a body which proceeds from a region 

 whose temperature was superior to that of its present situa- 

 tion ; or, if we wish, it is a thermometer, moveable in space, 

 which has not time, in consequence of its great dimensions 

 and its degree of conductibility, to take in through its whole 

 mass the temperature of the different regions which it tra- 

 verses. At present, the temperature of the globe increases 

 below its surface. The contrary has already, and will again 

 take place. At other periods, besides at epochs separated 

 by numerous ages, this temperature ought to be, and will 

 be, by consequence, much higher or much lower than it is 

 now, which prevents the earth from being always habitable 

 by the human species, and has, perhaps, contributed to the 

 successive revolutions of which its external layer has pre- 

 served the traces."* 



2. Theory of heat and light. — Ampere, in stating his views 

 in reference to a theory of heat, sets out with defining par- 

 ticles, molecules, and atoms which he considers to enter into 

 the constitution of matter. A. particle is an infinitely small 

 portion of a body, and of the same nature with it, so that a 

 particle of a solid body is solid, that of a liquid body liquid, 

 and that of a gas aeriform. The particles are composed of 

 molecules kept at a distance : 1 . By what remains at this 

 distance, of the attractive and repulsive forces peculiar to 

 the atoms ; 2. By the repulsion which the vibratory motion 

 of the interposed ether establishes between them : and 3. 

 By the attraction directly proportional to the masses, and 



* Bibliotheque Universelle, June, 1855. Ann. de Cliimie, lix. 71. 



