might have seen the glare of countless volcanoes diffused, lurid and
threatening, over the face of their satellite! How strange the thought
that the once active fires should all have died away, and the Moon have
thus been prepared for the better reception and reflection of the solar
radiance in order to illuminate the nights of Earth!

The planets, needless to say, were the objects of Herschel's assiduous
attention. Mercury was the one which least interested him; but he
ascertained the perfect circularity of its disc. With respect to Venus,
he endeavoured to determine the time of its rotation from 1777. We owe
to him the discovery of the true shape of the "red planet Mars,"--that,
like the Earth, it is an oblate spheroid, or flattened at the poles.
After Piazzi, Olbers, and Harding had discovered the small planets,
Ceres, Pallas, Juno, and Vesta, he applied himself to the measurement
of their angular diameters. His researches led him to the conclusion
that these four new bodies could not properly be ranked with the
planets, and he proposed to call them Asteroids--a name now generally
adopted. Since Herschel's time, the number of these minor planets known
to astronomers has increased to upwards of one hundred.

With respect to Jupiter, our astronomer arrived at some important facts
in connection with the duration of its rotation. He also made numerous
observations on the intensities and comparative magnitudes of its
satellites.

We come next in order to Saturn, the gloomy planet which the ancient
astrologers regarded with so much dislike. Here, too, we find traces
of Herschel's labours. Not only has he enlarged our knowledge of its
equatorial compression, of its physical constitution, and of the
rotation of its luminous belt or ring, but he added two to the number