ASTRONOMY. 



moon, and that nearly in the ratio of 3 to 2 ; but 

 fewer eclipses of the sun are observed in any given 

 place than of the moon, as a lunar eclipse is visi- 

 ble to a whole hemisphere ; but a solar only to a 

 part. 



151. The general phenomena of the eclipse 

 being calculated to the time of a given meridi- 

 an, the phenomena, as they will be observed at 

 any particular place, may also be determined, 

 by calculating the altitudes of the sun and moon, 

 and the effects of their parallaxes for different 

 instants of time, and then employing the me- 

 thod of interpolation, to determine the time of 

 the beginning and end, and the quantity of the 

 greatest obscuration. 



a. Let the places of the sun and moon be found for 

 an instant, far from the beginning of the eclipse, 

 and from thence let their altitudes for the given 

 place be computed, as also the effects of parallax 

 in longitude and latitude. 



Let the difference of the apparent longitude of the 

 two bodies thus found be called , and the latitude 

 of the moon A. If the sun's parallax is included, 

 let his parallax in latitude be applied to the moon, 

 taking notice, whether it increases or diminishes 

 the difference of latitude. Then ACB, fig. 15. be- 

 ing an arch of the ecliptic, A the place of the sun, 

 D of the moon, as just computed, P the pole of 

 the ecliptic, and PDC a circle of longitude, AC 



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