1874.] The Saturnian System. 23 
the light of the following planets, regarded as light-reflecting 
bodies, indicated the tabulated reflecting powers :— 
Monte acs sls a6 6. i, (CO L720 
Marss (Sis say es Or 2072 
(pILSEa-! cape 2 e) O10Z36 
Satu: .- w4,” us. | 3 MOMOSE 
Uranus 7s). Ve) 0<) ay 5. “OO700 
Neptine Wis ss - a Ort04G7 
The following determinations of the reflecting powers of 
terrestrial substances indicate the significance of Zollner’s 
results :— 
Snow just fallen . . . 0°783 
White paper << =. « (0°700 
White sandstone . . . 0°237 
lag Mae si, eo pis ts ate Y O'L5O 
Ouartz porphyty =. « o-108 
MOISE. SOM: 4s. oe @ +o). 07079 
Dark erey syenite.. . . o078 
I have discussed at some length and in various aspects, 
in my ‘‘ Other Worlds” and Essays on Astronomy, the 
evidence in favour of occasional actual change in the shape 
of Saturn. It seems to me that it may now be desirable to 
quote the ipsissima verba of Sir W. Herschel as to the so- 
called square-shouldered aspect of Saturn. It must be 
mentioned in the first place that no possible question can 
now exist as to the ordinary shape of Saturn’s disc being 
that of an ellipse. Herschel himself was not quite sure 
whether the square-shouldered aspect might not have been 
presented even when he made those earlier measurements 
which seemed to indicate a truly elliptical figure. But as we 
now know from the measurements of Main, Bessel, and 
others that the ordinary figure of Saturn is elliptical, we see 
what interpretation can alone be placed on the observations 
now to be quoted, if accepted. 
It is customary to assign April, 1805, as the first occasion 
on which Herschel perceived any departure from the 
elliptical figure. But he himself quotes the following 
observation, made 17 years earlier :— 
* I may note, by the way, that, considering the enormous difficulty of 
determining the dimensions of the planet Neptune, it may be questioned 
whether the above result might not suggest that the real dimensions of 
Neptune are less than usually stated, and therefore the albedo greater than 
above indicated. Of course it would be extremely rash to assume this on the 
strength merely of the fa& that Neptune has a less albedo than any of his 
fellows among the giant planets. Still the point is worth noting. 
