ASTRONOMY. 153 



which every one of them appears to be central, is a 

 narrow belt, perhaps a mere mathematical line, 

 traced across the enlightened hemisphere of the 

 earth. 



g. A central eclipse is annular, when the angle sub- 

 tended by the sun's diameter is greater than that 

 subtended by the moon's 5 it is total for an instant, 

 or sine mord, when these angles are equal ; and it 

 is total for a portion of time that can never exceed 

 eight minutes, when the angle subtended by the 

 moon's diameter is greater than that subtended by 

 the sun's. 



h. A central eclipse observed at London in April 

 1715, is described by Dr HALLEY. The darkness 

 for a few minutes was so entire, that the stars be- 

 came visible. Though the disk of the sun was 

 wholly covered by the moon, a luminous ring of a 

 faint pearly light surrounded the body of the moon 

 the whole time. Its breadth was about a tenth of 

 the moon's diameter. The longest time that the 

 obscuration lasted any where in Britain, was about 

 3m 57s. Phil. Trans, vol. 29. p. 295., &c. ViNCE, 

 Astron. vol. 1. 585. 



Occupation 



