A. MATHEMATICS AND ASTRONOMY. 43 



Jupiter, the Earth, and Venus, can produce on its surface the 

 great phenomena that it presents to iis. 



6. According to Sir John Herschel, the sun is a nucleus, 

 solid and cold, surmounted by many gaseous envelopes : in 

 the exterior envelope, under the influence of trade Avinds, 

 there form cyclones that penetrate perhaps into the interior 

 envelopes that is to say, into the photosphere and into the 

 region of the iDenumbra. By the admission of such impossible 

 hypotheses science is much injured. 



7. According to Mayer and Waterston, the sun is a body 

 heated by the incessant collision of aerolites that fall upon 

 its surface. This seems to be the germ of a grand idea, but 

 fettered by the use of hypotheses. 



Finally, Mr.Vicaire proposes to consider the sun as a com- 

 bustible body, that has been burning since a certain ej^och in 

 an oxidizing atmosphere. 



As for himself, Faye says that he has endeavored to avoid 

 all hypotheses, to simply study the movements of the spots, 

 and establish from them such laws of nature as may result 

 therefrom. 6 B, 1873, 301. 



THE TEMPERATURE OF THE SUN's SURFACE. 



On this subject Zollner, some three years ago, published 

 some interesting investigations, in which he sought to de- 

 termine the minimum limit which we must ascribe to the 

 temperature of the sun. As the result of his very critical 

 calculations, he found, for the temperature of the glowing 

 fluid surface, 13,230 degrees Centigrade. On the other hand, 

 the temperature at a depth, below his surface, of one-fortieth 

 part of the sun's radius, he concluded must be something 

 over 1,000,000 degrees Centigrade. DiflTering from him, 

 Secchi comes to the result that the temperature of the sur- 

 face must amount to 5,000,000 degrees or more, and that 

 this is the lowest limit that we can possibly adopt. These 

 two results are so discordant with each other that Zollner 

 has undertaken, in a second investigation, to arrive at the 

 desired temperature by an entirely different method of rea- 

 soning. It is evident that any method for the determination 

 of any physical peculiarity of the sun, based on measure- 

 ments and principles derived from our experience on the 

 earth, w^ill yield the more probable results in proportion as 



