ighly probable that there are still more.' Whewell, also, in his
'Bridgewater Treatise,' says, 'that though it no longer appears probable
that Uranus has a ring like Saturn, he has at least five satellites
which are visible to us, and we believe that the astronomer will hardly
deny that he' (Uranus, not the astronomer), 'may possibly have thousands
of smaller ones circulating about him.' But in this case Sir W.
Herschel, anxiously though he endeavoured to guard against the
possibility of error, was certainly mistaken. Uranus may, for anything
that is known to the contrary, have many small satellites circulating
about him, but he certainly has not four satellites (besides those
known) which could have been seen by Sir W. Herschel with the telescope
he employed. For the neighbourhood of the planet has been carefully
examined with telescopes of much greater power by observers who with
those telescopes have seen objects far fainter than the satellites
supposed to have been seen by the elder Herschel.

The third of the Herschelian myths was the lunar volcano in eruption,
which he supposed he had seen in progress in that part of the moon which
was not at the time illuminated by the sun's rays. He saw a bright
star-like point of light, which corresponded in position with the crater
of the lunar mountain Aristarchus. He inferred that a volcano was in
active eruption because the brightness of the point of light varied from
time to time, and also because he did not remember to have seen it
before under the same conditions. There is no doubt something very
remarkable in the way in which this part of the moon's surface shines
when not illumined by the sun. If it were always bright we should
conclude at once that the earth-light shining upon it rendered it
visible. For it must be remembered that the part of the moon which looks
dark (or seems wanting to the full disc) is illuminated by our earth,
shining in the sky of the moon as a disc thirteen times as large as that
of the moon we see, and with the same proportion of its disc sunlit as
is dark in the moon's disc. Thus when the moon is nearly new our earth
is shining in the lunar skies as a nearly full moon thirteen times as
large as ours. The light of this noble moon must illumine the moon's
surface much more brightly than a terrestrial landscape is illumined by
the full moon, and if any parts of her surface are very white they will
shine out from the surface around, just as the sn