Washington sentinel. [volume] (Washington [D.C.]) 1853-1855, 1853-10-02

paratus is made to revolve in a given time, the
ratio Of the flashes to the eciipses will be as one
to two-if The revolution is made in twelve min
atcs, leach pannel occupying Is degrees WILDE the
l-24th Of ~ minutes or 30 seconds, in passing
the eye and the flash covering s degrees, will
eclipse being ~ seconds.
The light is produced by gle lamp placed
in the common focus 1t is carcel lamp, with
burner of 4 concentric wicks, the largest being
nearly four inches in diameter. These wicks
are kept constantly saturated with oil, which is
pumped up from a reservoir below, thus pre-
venting undue carbonization, and producing
the maximum briliancy. The supplying pumps
are moved by clock-work The lamp, consist
ing Of the cock-work, reservoir, and burner,
sits upon a tripod resting on the stationary part
of the apparatus and by means OF set-screws
can be very nicely adjusted in the focal plane.
A cast iron column, or pedestal, sustains the
whole structure, and has on it shoulder with
bed plate Of steel, with beautiful arrange
ment Of friction wheels and rollers by which the
movable framework is supported and enabled
to revolve. Motion is given to this by hand.
some piece Of clock!work. The whole machinery
and all the iron and brass work, are very CON-
plete, and well worthy Of inspection.
The first apparatus Of this kind imported in.
to this country was one OF the lst and one OF
the I'd order, erected at the highlands of the
1850. the bureau of Typographical engineers,
having charge of certain lighthouses, placed
one Of the Sd order in the lighthouse on Bran
DIVINE shoal, Delaware Bay-one Of the Sd
order on the Waugoochance light, Lake Michi-
gan, and one of the first order at Sand Key,
Gulf Of Florida. This is the third apparatus of
the LIST ORDER or largest size, imported into this
country, and was ordered by the lighthouse
board for Cape Hatteras, where the dangers OF
navigation require that no efforts or expense
should be spared to have the best light.
The power Of the light exhibited is not accu-
rately known. The illuminating effect Of Fres-
nel's great lens has generally been taken at
5000 argand burners value of the flame
at its focus being about l6-thus giving the in
creasing power of the lens $50. These lenses,
with the upper and lower rings Of this appa-
ratus, will, Of course, produce much greater
effect.
The consumption Of oil in the lamp is about
600 gallons per annum. Comparing the amount
Of light with the quantity Of oil consumed, re-
volving lights on the doptric or refracting prin-
ciplc use oil more economically than those, in
the catoptric or rejecting plan, in the ratio Of
3G to l.
The power Of these lights is also great con-
sderation in their favor-cnabling them to
penetrate fogs and be visible at times when a
feeble light would be lost. They can be seen
as far as the curvature OF the earth will admit;
and Il case is known where the elevation OF the
light or the coast of France and Of the observer
on the English shore, was such as to make the
French light distinguished at the distance Of
fifty miles. They are almost entirely employed
in France and on the continent of Europe, and
are gradually being put up in England, the
great Sherryvorc light house having one.
1t is believed to be the wish Of the light
house board to introduce them into all our first
class or scacoast lights; and it is, therefore, Of
great importance that all persons interested in
| commerce and navigation should visit and in
spect the apparatus, and use their influence to
produce the desired result.
TO the notes, and to Captain Mead's oblig-
ing explanation, we are indebted for the mate
rails OF this article There is also a very in.
reresting paper on the subject i'll Appleton's
useful Dictionary of Machines, &c, although it
is there very enormously stated "that the ca
toptric or reflector system is the only one in
use in the United States p. 663
1t thus appears that we are indebted to
French skill and genius, not only for some of
the most exquisitely beautiful, but also for one
Of the most useful objects that the palace con-
tains.
The graceful forms and unmatched coloring
Of the Sevrcs porcelain, the magic web OF the
Gobcin tapestries have been for a century the
theme OF universal admiration; but in nothing
is the adaptation Of skill and science to the
works Of man seen to greater advantage than
in this interesting and novel benefcent con-
trivancc Of it's French inventor.
The inscription placed on the great Pharos
Of Egypt by its architect was in these simple
and touching words: "Sostratus Of Cnidos, the
son of Deyiphanez, to the gods. the saviours,
for the benefit of seamcn. Some phrase
equally simple, equally expressive Of the rev.
erence due to superior1n"wcr>, expressing, too,
the surprising beauty and usefulness of great
abilities devoted to the cause "t humanity,
should be placed the tomb Of Ausustin
Fresnel.