THE PLANET SATURN IN JULY 1869. 
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scopes, will avail themselves of every interval of good observing 
weather to scrutinise the Saturnian system. The spectroscope, 
too, which has already afforded singular and interesting infor- 
mation respecting the rings, will probably be brought to bear 
afresh upon the question of their structure. We propose now 
to consider some of the discoveries which have been recently 
made respecting Saturn and his system, and to suggest some 
processes of observation which, if well carried out, might afford 
valuable information on the subject of the rings. 
I shall assume a knowledge on the reader’s part of all those 
features of the Saturnian system which are usually described in 
treatises on astronomy. Nor shall I enter at any length into the 
circumstances which have led astronomers to recognise, in the 
system of rings, the presence of a multitude of discrete particles 
or minute satellites, revolving for the most part in one plane 
around the globe of the planet. I must make one or two pre- 
liminary remarks on this interesting hypothesis, however, lest 
some portions of what follows should not seem intelligible to 
those who may not happen to be familiar with the views now 
received. 
It had been shown, by Laplace, that the stability of the 
motion of such rings as were supposed to surround Saturn 
could only be maintained by a considerable over-weighting of 
one portion of each ring, and an equally remarkable eccentricity 
of position. Later astronomers, admitting this view as the 
basis of their inquiry, came to the conclusion that the disturbing 
action of the satellites might cause a balancing motion in the 
ring-system, sufficient at least to secure stability, somewhat as 
the slight motions by which a rod is balanced in an upright 
position, although these motions are severally opposed to the 
rod’s stability, yet by their united effect give to the rod a com- ^ 
parative fixity of position which the most perfect quiescence of 
the support could not secure. These views maintained their 
ground until the discovery of the dark ring, and of the strange 
fact, that the planet’s body could be seen through this forma- 
tion without apparent distortion. The discovery of this ring 
led to a renewed examination of the problem ; and finally 
Professor Maxwell of Cambridge proved, liy a most convincing 
process of mathematical demonstration, that no solid ring 
could by any possibility continue to exist as an attendant 
upon a planet. Either the ring would crumble into frag- 
ments under the influence of the forces to which it would be 
subjected, and these fragments would continue to revolve as a 
broken ring round the planet ; or the ring would be more com- 
pletely destroyed, and would be brought to the planet’s surface. 
Hence we are forced to conclude that the rings, though con- 
