Miscellaneous. 473 



3,300 B. C, thus assigned to these structures, accords with Bun" 

 sen's determination, according to which king Cheops reigned in 

 the thirty-fourth century before our era. It also agrees with the 

 tradition of the Arabs, according to which they were constructed 

 three or four centuries before the deluge ; which they assign to 

 the year 3,716 before the Hegira. — {Le Cosmos, JVov.21st, 1862.) 



T. .S .H. 



ON THE CAUSE OF ATTRACTION. 



The Rev. Father Secchi, the learned director of the Roman As- 

 tronomical Observatory, has just published an essay, in which he 

 discusses from an advanced point ' >f view the theory of attraction 

 After having shown, in accordance with the views so ably ex- 

 pounded by Mr. Tyndal in his paper on Force, published in the 

 Naturalist, (p. 241,) that all the physical forces or movements of 

 which we are cognizant come to us from the solar centre, the 

 learned Jesuit inquires, " But how does this movement or se- 

 ries of movements return to the sun ? Who knows but what that 

 part of the heat thus emanating from the sun, which is not lost 

 by radiation into space, is converted into an impulsion of the 

 mass of the earth towards the sun ? I do not pretend to give a 

 theory, but only to propose a conjecture, which it will be suffi- 

 cient for me to show not to be absurd." 



" We see that the intensity of heat, like that of gravity, dimi- 

 nishes inversely as the square of the distance. We know also 

 that a prodigious quantity of molecular movements come from 

 the sun by luminous and calorific radiation, and under the form 

 of vibratory disturbances, remain, apparently destroyed, at the 

 earth's surface, instead of being lost by radiation towards the 

 planetary spaces. In fact, heat coming from sources of a very 

 high temperature (that is to say, heat of short undulations,) when 

 brought to a lower temperature, (or to long undulations,) can no 

 longer traverse the terrestrial atmosphere and radiate into space. 

 A certain quantity of motion coming from the sun must thus rest 

 imprisoned in terrestrial bodies, by the chemical force to which it 

 gives rise. So that in reality the vis viva, and the quantity of move- 

 ment in the terrestrial globe, and its surrounding mass of ether, 

 must increase indefinitely, if there were not some way of escape 

 or discharge. Why may not this discharge be the incessant fall 

 of the earth towards the sun, a fall expressed by the linear dis- 



