eters (over 25 miles). At the distance of Mercury it = 47 x
1.414 or 66,400 meters (over 40 miles) per second.

Among the numerous comets observed, we do not as yet know more than some
twenty of which the orbit has been determined. Periodicity in these
bearded orbs is thus exceptional, if we think of the innumerable
multitude of comets that circle through the Heavens. Kepler did not
exaggerate when he said "there are as many comets in the skies as there
are fishes in the sea." These scouts of the sidereal world constitute a
regular army, and if we are only acquainted with the dazzling generals
clad in gold, it is because the more modest privates can only be
detected in the telescope. Long before the invention of the latter,
these wanderers in the firmament roamed through space as in our own day,
but they defied the human eye, too weak to detect them. Then they were
regarded as rare and terrible objects that no one dared to contemplate.
To-day they may be counted by hundreds. They have lost in prestige and
in originality; but science is the gainer, since she has thus endowed
the solar system with new members. No year passes without the
announcement of three or four new arrivals. But the fine apparitions
that attract general attention by their splendor are rare enough.

These eccentric visitors do not resemble the planets, for they have no
opaque body like the Earth, Venus, Mars, or any of the rest. They are
transparent nebulosities, of extreme lightness, without mass nor
density. We have just photographed the comet of the moment, July, 1903:
the smallest stars are visible through its tail, and even through the
nucleus.

They arrive in every direction from the depths of space, as though to
reanimate themselves in the burning, luminous, electric solar center.

Attracted by some potent charm toward this dazzling focus, they come
inquisitive and ardent, to warm themselves at its furnace. At first pale
and feeble, they are born again when the Sun caresses them with his
fervid heat. Their motions accelerate, they haste to plunge wholly into
the radiant light. At length they burst out luminous and superb, when
the day-star penetrates them with his burning splendor, illuminates them
with a marvelous radiance, and crowns them with glory. But the Sun is
generous. Having showered benefits upon these gorgeous celestial
butterflies that flutter round him as round some altar of the gods, he
grants them liberty to visit other heaven