st have
given the keeper abundance of occupation in the way of snuffing and
replenishing.

In 1789 a French scientist, M. Lenoir, made an epoch in the history of
Light-houses, and in the progress of civilization as well, when he
introduced an improvement in the way of lighting up the _Tour de
Corduan_; for, of course, the comparative safety in coast navigation
attained to by means of our modern Light-house system is of the first
consequence in commerce and international communication, which means the
spread of science, enlightenment and religion throughout the world. M.
Lenoir placed Argand lamps with parabolic mirrors or reflectors in the
lantern, which is, as it appears, a glass room on the summit of the tower
entered by a trap-door at the head of a spiral staircase. Such a great
change having been brought about, men of science have not rested content,
but have gone on making one advance after another. In 1820 the famous
diaptric instruments of Mr. Fresnel were placed in Corduan on trial, and
proved such a grand success that, gradually, they have been universally
adopted. The wonderful lens which you saw at the Centennial belongs to a
diaptric refracting light of the first order, and oil lamps constructed
on the Fresnel principle, and, placed with lenses of different orders,
according to the Light-house they are used for, serve an admirable
purpose. Lard is found to be the best illuminator, as a general thing,
for the light it casts through lenses of the first order reaches as far
out to sea as it is possible for any light to be seen on account of the
convexity of the earth. Experiment has proved it safer than mineral oil,
and it is cheaper than gas, which however is occasionally used near a
city whence it can easily be obtained. Only in some few special instances
electric light, the most intense procurable, is employed.

[Illustration: LIGHT-HOUSE ON MT. DESERT, COAST OF MAINE.]

The Centennial birth-day gift of the citizens of France to the American
Republic is a colossal brazen statue of Liberty, which is to be a Pharos
to light the shipping of the world into New York harbor. It will stand on
Bedloe's Island, and from the torch in its uplifted hand will flash a
calcium light. Only the hand and arm were finished in time to be sent to
the Exposition; but these were on so gigantic a scale that a man standing
in the little gallery which ringed the thumb holding the torch seemed
like an ant or a fly creeping along at