Curiosities of Science. 23 



the atmosphere is calculated to be fifty miles in altitude ; the 

 loftiest mountain peak is estimated at five miles above the level 

 of the sea, for this height has never been visited by man ; the 

 deepest mine that he has formed is 1650 feet; and his own 

 stature does not average six feet. Therefore, if it were possible 

 for him to construct a globe 800 feet or twice the height of 

 St. Paul's Cathedral in diameter, and to place upon any one 

 point of its surface an atom of 45 ' 6(j th of an inch in diameter, 

 and ^th of an inch in height, it would correctly denote the 

 proportion that man bears to the earth upon which he moves. 

 When by measurements, in which the evidence of the method ad- 

 vances equally with the precision of the results, the volume of the earth 

 is reduced to the millionth part of the volume of the sun. ; when the sun 

 himself, transported to the region of the stars, takes up a very modest 

 place among the thousands of millions of those bodies that the telescope 

 has revealed to us ; when the 38,000,000 of leagues which poparate the 

 earth from the sun have become, by reason of their comparative small- 

 ness, a base totally insufficient for ascertaining the dimensions of the 

 visible universe ; when even the swiftness of the luminous rays (77,000 

 leagues per second) barely suffices for the common valuations of science; 

 when, in short, by a chain of irresistible proofs, certain stars have re- 

 tired to distances that light could not traverse in less than a million of 

 years ; we feel as if annihilated by such immensities. In assigning to 

 man and to the planet that he inhabits so small a position in the ma- 

 terial world, astronomy seems really to have made progress only to 

 humble us. Arago. 



MEAN TEMPERATURE OF THE EARTH'S SURFACE. 



Professor Dove has shown, by taking at all seasons the 

 mean of the temperature of points diametrically opposite to 

 each^ other, that the mean temperature of the whole earth's sur- 

 face in June considerably exceeds that in December. This re- 

 sult, which is at variance with the greater proximity of the 

 sun in December, is, however, due to a totally different and 

 very powerful cause, the greater amount of land in that 

 hemisphere which has its summer solstice in June (i. e. the 

 northern) ; and the fact is so explained by him. The effect of 

 land under sunshine is to throw heat into the general atmo- 

 sphere, and to distribute it by the carrying power of the latter 

 over the whole earth. Water is much less effective in this 

 respect, the heat penetrating its depths and being there ab- 

 sorbed ; so that the surface never acquires a very elevated 

 temperature, even under the equator. Sir John HerscheVs 

 Outlines. 



TEMPERATURE OF THE EARTH STATIONARY. 



Although, according to Bessel, 25,000 cubic miles of water 

 flow in every six hours from one quarter of the earth to another, 

 and the temperature is augmented by the ebb and flow of every 



