on excited in his mind the
intensest interest. He sought for the explanation of the fact in the
doctrine of refraction. He meditated day and night. At last he himself
constructed an instrument,--a leaden organ pipe with two spectacle
glasses, both plain on one side, while one of them had its opposite side
convex, and the other its second side concave.

This crude little instrument, which magnified but three times, he
carries in triumph back to Venice. It is regarded as a scientific toy,
yet everybody wishes to see an instrument by which the human eye
indefinitely multiplies its power. The Doge is delighted, and the Senate
is anxious to secure so great a curiosity. He makes a present of it to
the Senate, after he has spent a month in showing it round to the
principal people of that wealthy city; and he is rewarded for his
ingenuity with an increase of his salary, at Padua, to one thousand
florins, and is made professor for life.

He now only thinks of making discoveries in the heavens; but his
instrument is too small. He makes another and larger telescope, which
magnifies eight times, and then another which magnifies thirty times;
and points it to the moon. And how indescribable his satisfaction, for
he sees what no mortal had ever before seen,--ranges of mountains, deep
hollows, and various inequalities! These discoveries, it would seem, are
not favorably received by the Aristotelians; however, he continues his
labors, and points his telescope to the planets and fixed stars,--but
the magnitude of the latter remain the same, while the planets appear
with disks like the moon. Then he directs his observations to the
Pleiades, and counts forty stars in the cluster, when only six were
visible to the naked eye; in the Milky Way he descries crowds of
minute stars.

Having now reached the limit of discovery with his present instrument,
he makes another of still greater power, and points it to the planet
Jupiter. On the 7th of January, 1610, he observes three little stars
near the body of the planet, all in a straight line and parallel to the
ecliptic, two on the east and one on the west of Jupiter. On the next
observation he finds that they have changed places, and are all on the
west of Jupiter; and the next time he observes them they have changed
again. He also discovers that there are four of these little stars
revolving round the planet. What is the explanation of this singular
phenomenon? They cannot be fixed stars, or