PROCEEDINGS OF THE CANADIAN INSTITUTE. 103 



Recent Views Respecting the Constitution of the Sun, Bv Arthur 

 Harvey, Esq., F.R.SC. 



( Read joth November, i()Oi.) 



At the base of a mouutaiu the view is usually limited and obscured, but the 

 horizon widens and the prospect gains in clearness on the upward climb. Still, 

 when the Alp is scaled, pealis beyond peaks become visible. So in science, and 

 especially in iistronomy, some new fact or theory is daily added to the general 

 store, but it is only thereby made evident that there is far more beyond our ken 

 than within it, and we are compelled to think of the last words of Laplace : — 

 " Ce que nous savons est peu de choses ; ce que nous ignorons c'est immense ! " 



The sun is the orb of which, in comparison with its importance, we know 

 least, and its various phenomena are almost all, as yet, mere riddles. What was 

 thought fifty years ago to be assured knowledge has not held firm, while even 

 modern views as to his constitution are uncertain and indefinite, notwithstanding 

 the array of new facts of which we have become the masters through the aid of 

 the huge telescopes, the perfected spectroscopes and the photographic instruments 

 lately brought into use. 



Changed views as to the sun have been forced upon us by the alteration of 

 our ideas about the earth, in which, too, there has been a revolution within a life 

 time. 



No longer are we told that the height of our air is forty miles. Aurora- can 

 now with reasonable certainty be numbered among atmospheric phenomena and I 

 have proved one remarkable auroral arch to have been over 150 miles above the 

 ground.* We now know that falling stars light up by friction in the air, and in 

 tracing the path of a remarkable bolide seen in Toronto, I learned that it became 

 luminous at the height of 80 or 100 miles. t The trail of that meteor became 

 snake-like before it vanished, the sinuosities having a breadth of half the apparent 

 diameter of the moon. If these were caused by air- waves, such as Mr. Napier 

 Deuison has told us of,. I; these waves had a breadth of at the least 2,000 feet. 

 Laplace, a hundred years ago, said the atmosphere was bounded by a lenticular 

 shaped surface of revolution whose volume is about 155 times that of the solid 

 earth and should reach out to a distance of about 26,000 miles at the equator and 

 17,000 at the poles. Professor Woodward, lately President of the Mathematical 

 Society of America, appears to agree with him.iJ New gases have been discovered 

 in the air, and its constitution is even thought to change as we ascend in it. 

 Carbon dioxide decreases, hydrogen increases and it is thought by some that on 

 the aerial outskirts there is hydrogen alone or with the smallest admixture of the 



* Transactions Astronomical Society of Toronto, 189.1, p. 78. 



t Transactions Astronomical Society of Toronto, i8q8, p. 1 18. 



* Transactions Canadian Institute, February 6th, 1897. 

 § Science. January i^tli, 1900. 



