AN EVENING WITH THE TELESCOPE. 115 



equator of Saturn is much larger than in our earth ; in 

 fact the elliptical form of Saturn is so evident as to be 

 at once detected without any delicate telescopic measure- 

 ments. The surface of the globe presents but few 

 features of interest, and indeed there is little on it which 

 can be depicted in a drawing. It is of a nearly uniform 

 whitish yellow colour, occasionally, however, marked over 

 with faint bands. It is obvious that what we see is merely 

 the outside of a great casing of cloud, in which the entire 

 planet is shrouded. In fact it seems very doubtful 

 whether Saturn bears any resemblance to a solid body at 

 all. Our first impression might perhaps be that the 

 planet was a sort of rigid globe like our earth, covered by 

 a coating of cloud, much deeper and denser, and more 

 uniformly distributed than the somewhat intermittent 

 clouds of which we on the earth have so often to complain. 

 But it is not easy to see how far the interior of Saturn 

 can, with propriety, be likened to a dense globe like ours, 

 and for the following reason : our earth is composed of 

 rocks and metals, and the entire weight of the globe is 

 above five times the weight that a globe of equal bulk of 

 water would have. It may seem a very difficult problem 

 to weigh the planet Saturn, and so to compare its mass 

 with that of an equal globe of water, but the task is not 

 beyond the resources of the practical astronomer. When- 

 ever a planet is provided with satellites, or little attendant 

 moons, it is possible to put the great globe into the weigh- 

 ing scales and to determine how heavy it is. I cannot 

 here delay to explain fully the details of the process ; suf- 

 fice it to say that it can be done with great accuracy, 

 and the result in the case of Saturn is truly astonishing. 



