Mr. Smith on the Planet Saturn. 59 
slightly on the subject, that the ring was constructed for the 
purpose of enlightening the planet in the absence of the sun. 
‘To those who advance this opinion it may be replied, that for 
the purpose of illumination the ring is worse than useless, in- 
asmuch as that it intercepts more of the sun’s light from the 
planet than it reflects towards it. To exemplify this, let us as- 
sume any particular spot on the surface of Saturn. Suppose a 
spot whose latitude is equal to that of London. Now by duly 
considering that the plane of the ring is inclined thirty degrees 
to the plane of Saturn’s orbit, it will be perfectly evident, that 
to the assumed spot the ring can only appear enlightened by 
the sun during one half of the year, and that the summer half; 
to which may be added, that all the portion of the ring which 
at midnight is near the meridian, must be eclipsed by the body 
of the planet. The phanomena actually observed will there- 
fore be as follows; viz. Immediately after sunset an arm of 
the ring will appear in the west,. which will gradually shorten 
and finally set; but before it entirely disappears, another si- 
milar arm will rise in the east, and gradually lengthen until 
the superior brilliance of the ascending sun supersedes its use 
as an object of illumination. About the period of the summer 
solstice these two arms of the ring will unite so as to form an 
entire arch intersecting the horizon in the east and west, and 
inclined thereto at an angle equal to the co-latitude of the 
place, at which time there will certainly by considerable illu- 
mination. Still it may be remarked that the illumination is most 
perfect when least wanted. This therefore, as well as the fact 
that the planet is furnished with seven moons, is demonstra~ 
tive proof that the ring was not constructed for the purpose 
of illumination; and no other supposition remains than that it 
was formed to be a habitable world. It may further be re- 
marked, that although the ring cannot usefully enlighten the 
planet, yet the planet reflects a very strong light on the ring 
for about half of each period of ten hours; and therefore the 
annularians have no reason to regret that the satellites do not 
rise above their horizon, because the planet reflects them, per- 
haps, ten times more light than would be the united effect of 
all the satellites. 
The ring of Saturn is now known to be double, or to be in fact 
two concentric rings ; but this circumstance does not affect the 
justness of any of the foregoing arguments. Perhaps this di- 
vision may be advantageous to the inhabitants, as affording 
them a short cut from one surface of it to the opposite; or per- 
haps the adjustment of centrifugal force before alluded to, may 
require that the velocity of rotation should in a small degree 
differ in the two rings, in order to produce an equilibrium, or 
H 2 counterpoise 
