ed 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
of its satellites. Five only of these were known at the close of the
seventeenth century; of which Cussiric discovered four, and Huygens one.
It was universally believed that the subject was exhausted.

But, on the 28th of August 1780, Herschel's colossal tube revealed to
his delighted gaze a satellite nearer to the Saturnian ring than those
previously observed. And a few days later, on the 17th of September, a
seventh and last satellite crossed his field of vision. It was situated
between the former and the ring; that is, it is the nearest to it of the
seven.

But the most remarkable of Herschel's achievements was the discovery of
the planet Uranus, and the detection of its satellites.

On the 13th of March 1781, between ten and eleven o'clock at night, the
great astronomer was engaged in examining the small stars near H in the
conste