143 



less than - or whether the horizontal motion 

 ? 



of the moon in latitude, have to the sum of the ho- 

 rary motions of the moon and sun in longitude, a 

 less ratio than the sum of the semidiameters of the 

 moon and shadow has to the latitude of the moon 

 at the time of the conjunction. 



When the moon merely touches the shadow, that 

 is, when the nearest approach of the moon to the 

 shadow is just equal to the sum of the semidiame- 

 ters of the moon and of the section of the shadow, 

 we have what is called an Appulse. 



To derive as much advantage from the knowledge 

 of the ecliptic limits as possible, it is necessary to 

 observe, that when the mean opposition is 12 Q 36' 

 distant from the node, there can be no eclipse 5 

 and that when it is less than 9 distant from it, 

 there must be an eclipse. Between these limits 

 12 36' and 9, the matter is uncertain, and must 

 be decided by the calculation of the true place of 

 the moon, &c. These are the limits given by DE 

 LAMBRE 5 WOODHOUSE'S Astron. p. 34?2, The 

 limits are differently assigned by other writers, 

 VINCE, Astron. vol. i. 545. 



145. The moon seldom disappears entirely in 

 lunar eclipses ; even the spots may be distin- 

 guished 



