1874.] The Saturnian System. 5 
system. Jupiter | is indeed easily first, seeing that he 
surpasses about 2} times (in Mars) all the other members of 
the family, including Saturn, taken together. But Saturn 
is as easily second, seeing that he in turn surpasses all the 
other members of the planetary scheme, taken together, 
nearly three times. 
Still it is, when we compare either Jupiter or Saturn with 
the members of the terrestrial family of planets, or rather 
with that family as a whole, that we perceive most clearly 
that those giant planets belong to another order of bodies. 
Our earth does not to the same degree surpass the family of 
asteroids regarded as a whole. It is indeed rather surprising 
that the asteroids should so readily have been recognised as 
belonging to a distiné& order, while the giant planets, which 
differ fully as much from the terrestrial family of planets as 
these planets differ from the asteroids, should be regarded 
as though they were members of one and the same 
family. 
It may be urged, perhaps, that the asteroids by travelling 
altogether within a comparatively small region of the sun’s 
domain seem marked out as forming a distinct family. But 
in truth, the region within which the asteroids pursue their 
path is very much larger than that occupied by the members 
of the terrestrial family of planets—certainly twice as large, 
if we leave altogether out of account the great range of the 
asteroids in distance from the mean plane of the solar 
system. The orbital range of the terrestrial family of 
planets is indeed so small, compared with that of the outer 
family, that the two sets of orbits cannot be properly 
represented in the same diagram. If a diagram includes 
the orbits of the giant planets properly drawn to scale, then 
the path of Mars, the outermost of the terrestrial planets, 
is represented by a circle considerably smaller than that 
commonly used to represent the sun in ames of the solar 
system. 
Let us endeavour, then, to picture to anrSEInee the giant 
globe of Saturn pursuing its career so far from the central 
orb that the region girt round by its orbit exceeds more than 
ninety-fold the region which the earth circuits in her annual 
revolution. Let us remember that in precisely the same 
degree the solar light and heat are reduced at Saturn’s 
distance, and (also in the same degree) the attractive 
influence of the sun, and singularly enough, in the same 
degree, Saturn’s own attractive influence exceeds the earth’s. 
For the former relation was a necessary consequence of the 
law according to which light, heat, and gravity diminish 
