142 Professor T. E. Thorpe [June 9, 



WEEKLY EVENING MEETING. 



Friday, June 9, 1893. 



Hugo Muller, Esq. Ph.D. F.K.S. Vice-President, in the Chair. 



Professor T. E. Thorpe, D.Sc. F.R.S. M.B.I. 



The 'Recent Solar Eclipse.* 



Most people who take any interest in those larger problems with 

 which men of science are nowadays concerned are aware that there 

 are certain questions relating to the chemistry and physics of the sun 

 which, at present, can only be solved by observations made during the 

 fleeting moments of the total phase of a solar eclipse. Thanks to the 

 action of the Nautical Almanac office in this country, and of similar 

 institutions in other countries, we have not only ample warning of 

 the advent of an eclipse of the sun, but we are furnished with such 

 details concerning the time of its occurrence, the direction of the path 

 of the moon's shadow on the earth, and the duration of the various 

 phases, that we are enabled to decide whether it is expedient to at- 

 tempt to seize the precious seconds during which the sun is obscured 

 by the moon, in order to get further light on those questions which, 

 as has been said, can only be at present solved, or at least studied, at 

 such times. 



During the eclipse of last April the moon's shadow swept over 

 a considerable expanse of land. It touched the coast of Chili in 

 latitude 29° S. at about 8.15 a.m. of local time, passed over the high- 

 lands of that country, across the borders of Argentina and Paraguay, 

 and over the vast plains and forests of Central Brazil, emerging, at 

 about noon of local time, at a short distance to the north-west of 

 Ceara on the North Atlantic seaboard. Crossing the Atlantic, at 

 about its narrowest part, it struck the coast of Africa north of the 

 river Gambia, and finally disappeared somewhere in the Sahara. It 

 would seem, therefore, there was ample choice in the selection of 

 stations. But all situations were not equally good or equally avail- 

 able. There were, indeed, special reasons why every effort should be 

 put forth to observe this eclipse as completely as possible. To begin 

 with, it had an unusually long totality — upwards of four minutes at 

 places at or near the central line of the shadow. Next, it occurred 

 at about a period of maximum of solar energy, and hence we had an 



* A full report of the discourse is given in the • Fortnightly Keview,' July 

 1893. 



