PLATE VII. 



MOON'S AGE 21 DAYS, 5 HOURS. NOVEMBER 3, 1 890. LICK OBSERVATORY. 



In this plate the moon is entering on the fourth quarter. The rays of the Tycho system have 

 nearly disappeared. The two that are nearly parallel remain illuminated. So, too, the system of 

 Copernicus and that of Kepler to the southeast of it remain in nearly full glow. 



The vulcanoids near the south pole are better shown in this picture than in any other of the 

 series. That with several craters on its floor is Playfair. Note the craters on the inner face of its 

 wall. The same features can be observed in other like structures in this neighborhood. 



The Alps near Plato are fairly well shown, as are also the Apennines that border the western 

 side of the mare. The ruined craters about the M. Humorum are fairly well shown, but are faint. 



The tendency to form a crater or cone in the centers of the larger vulcanoids is fairly well 

 shown in those structures about the south pole. 



