80 The Astronomer Boyai on the 



others. In the annular eclipse of 1836 observed at Konigs- 

 berg, where the moon's limb but just entered completely on 

 the sun's, and where consequently it grazed along the sun's^ 

 for many seconds of time, the phenomenon appeared to resolve 

 itself simply into points of light seen between lunar moun- 

 tains. The Lecturer expressed himself generally satisfied 

 with Professor Powell's explanation, that the phenomenon 

 originates in that inevitable fault of telescopes and of the 

 nervous system of the eye which tends to extend the images 

 of luminous objects (producing what is generally termed 

 irradiation), and thus enlarges the sun's disk towards the 

 sky, towards the moon or planet, and towards the bottoms 

 of its hollows. 



In describing the total eclipse of 1842 (which perhaps was 

 better observed than any one preceding it) the Lecturer in- 

 sisted on our obligation to M, Arago, who had prepared the 

 preliminary notices, and used his powerful personal influence 

 in inducing persons to make observations at numerous stations 

 in the south of France ; and had afterwards collected and 

 compared the observations. Besides these French observa- 

 tions, and the observations made by astronomers officially 

 located in the path of the shadow, we have the observations 

 of M. Schumacher who went to Vienna, of MM. Otto Struve 

 and Schidlowsky at Lipetsk (the former of whom was sent 

 expressly by the Russian government), of Mr Baily who 

 went to Pavia, and of the Lecturer himself who went to the 

 Superga (near Turin). 



It appears that, with M. Arago's telescope, the whole cir- 

 cumference of the moon was visible when the moon had 

 entered on only about two-thirds of the sun's diameter. 

 Whatever may be the cause of this unusual appearance, it 

 seems to require the use of a telescope with a small number 

 of glasses in the highest state of polish. 



As the totality approached, a strange fluctuation of light 

 was seen by M. Arago and others upon the walls and the 

 ground, so striking that in some places children ran after it 

 and tried to catch it with their hands. 



Of the awful efi'ect of the totality, and of the suddenness 

 with which it came on, it is difficult to give an idea. The 



