OUTLINES OF NATURAL PHILOSOPHY. 



Number of Eclipses. 



a. In the space of eighteen years, there are usually 

 about 70 eclipses, 29 of the moon, and 41 of the 

 sun. These numbers are nearly in the proportion 

 of 2 to 3. 



b. Seven is the greatest number of eclipses that can 

 happen in a year, and two the least. 



c. If there are seven, five must be of the sun, and two 

 of the moon. If there are only two, they must be 

 both of the sun ; for in every year there are at 

 least two eclipses of the sun. 



d. There can never be more than three eclipses of the 

 moon in a year ; and in some years there are none 

 at all. 



c. Though the number of solar eclipses is greater 

 than of lunar in the ratio of 3 to 2, yet more lunar 

 than solar eclipses are visible in any particular 

 place, because a lunar eclipse is visible to an entire 

 hemisphere, and a solar is only visible to a part. 

 VINCE'S Astron. 588. 



f* Central Eclipses are comparatively rare phenome- 

 na , for though there are about 28 such eclipses 

 in every cycle of eighteen years, yet the space over 



which 



