64 ECLIPSE*. [Lesson xiv. 



from them ; till they become only partial ones, and 

 at last not at all. 4. The Moon, even in the 

 middle of an eclipse, has usually a faint appear- 

 ance of light, resembling tarnished copper; which 

 Gassendus, Ricciolus, and Kepler, attribute to the 

 light of the Sun, refracted by the Earth's atmos- 

 phere, and so transmitted thither. Lastly, she 

 grows sensibly paler and dimmer before entering 

 into the real shadow; owing to a penumbra which 

 surrounds that shadow to some distance. 



In addition to these circumstances, some astro- 

 nomers observe, and it is here added, that no 

 eclipse of the Moon can last above 5| hours, from' 

 the Moon's first touching the Earth's penumbra, 

 to its last leaving it : but an eclipse of the Moon, 

 by the Earth's shadow, perhaps never lasts above 

 3| hours; nor when total, above If hours. 



An Eclipse oj the Sun is an occultation or 

 hiding of the Sun's body from our sight, occasion- 

 ed by an interposition of the Moon between the 

 Earth and Sun. 



. Shorn of his beams, the Sun 



In dim eclipse disastrous twilight sheds, 



MILTON. 



It is by several considered and called an Eclipse 

 of the Earth, since the light of the Sun is hid from 

 the Earth by the Moon, whose shadow involves a 

 part of the Earth. The manner of a solar eclipse 

 may be conceived by imagining a small part near 

 the vertex of the Moon's conical shadow, travel- 

 ling over a part of the earth's surface, and making 



a com- 



