52!) MOONLIGHT. 



reappeared. Sometimes the darkening was less complete, so that at the 

 -Jtime of greatest darkness a portion of the moon seemed eaten out, though 

 mot by a well-defined or black shadow. These phenomena, they would 

 find, only at the time of full moon. And if they were closely observant, 

 they would find that these eclipses of the moon only occurred when the 

 full moon was on or near the great circle round the stellar heavens, which 

 they had learned to be the sun's track. They could hardly fail to infer that 

 •these darkenings of the moon were caused by the earth's shadow, near 

 •whicb the moon must always pass when she is full, and through which she 

 gnust sometimes pass more or less fully; in fact, whenever, at the time of 

 ■full, she ia on or near the plane in which the earth travels round the sun. 

 Solar eclipses would probably be observed later. For though a total eclipse 

 of the sun is a much more striking phenomenon than a total eclipse of the 

 ■^moon, yet the latter are far more common. A partial eclipse of the sun 

 ^anay readily pass unnoticed, unless the sun's rays are so mitigated by haze 

 ''Or mist that it is possible to look at his disk without pain. Whenever solar 

 •iBclipses came to be noted, and we know from the Chaldsean discovery of 

 the great eclipse period, called the Sgros, that they were observed at least 

 'two thousand years before the Christian era, the fact that the moon is an 

 opaque body circling round the earth, and much nearer to the earth than 

 the sun is, must be regarded as demonstrated. Not only would eclipses of 

 "the sun be observed to occur only when the moon was passing between the 

 «8arth and the sun, but in an eclipse of the sun, whether total or partial, the 

 round black body cutting off the sun's light wholly or partially would be 

 «een to have the familiar dimensions of the lunar orb. 



Leaving solar and lunar eclipses for description, perhaps, on another 

 occasion, I will now proceed to consider a peculiarity of moonlight which 

 inust very early have attracted attention — I mean the phenomenon called 

 "the harvest moon. 



The moon circuits the heavens in a path but slightly inclined to that of 

 ~the sun, called the ecliptic, and for our present purpose w^e may speak of 

 the moon as traveling in the ecliptic. Now we know that during the win- 

 ter half of the year the sun is south of the equator: the circle of the hea- 

 ■venly sphere which passes through the east and west horizon, and has its 

 plane square to the polar axis of the heavens. During the other or summer 

 'half of the year he is north of the equator. In the former case the sun is 

 ^bove the horizon less than half the twent3^-four hours, day being so much 

 Hhe shorter as the sun is farther south of the equator; whereas in the latter 

 'Case the sun is above the horizon more than twelve hours, day being so 

 much ttie longer as the sun is farther north of the equator. Precisely simi- 

 •lar changes affect the moon, only, instead of taking plao* in a year (the 

 time in which the sun circuits the stellar heavens), they occur in what is 

 ■called a sidereal month, the time in which the moon completes her circuit 

 of the stellar heavens. For about a fortnight the moon is above the horizon 

 longer than she is below the horizon, while during the next fortnight she 



