The New York herald., 1872-10-21

statistics and incidents that show the cause to
be worthy of the fullest support.
Great Nautical Invention.
Very recently an important and beautiful
scrutiny of the British Association by Mr.. w.
Froude, scientific gentleman Of some dis
tinction. The object of the inventor was to
produce an automatic apparatus which would
record the rolling of ship in seaway
and also register in graphic manner the
slopes of waves and the general undulations of
the ocean. The apparatus depends for it's
faithfulness and precision upon the simple
principle that plumb line or pendulum, if its
point Of suspension be near the ships centre
Of gravity, will be for the moment in equi-
ibrium if it occupy the normal position (or
that which the vessel would give it in still
water) and its oscillations will conform to
the changes of the wave slope. It consists,
according to the description of its contriver,
of revolving cylinder covered with paper
and turned by clock work, which causes it to
receive the tracings Of several pens. One of
these pens marks the time at equal successive
intervals by an exact clock. while, the instru-
ment being placed at the centre Of gravity of
the ship, pendulum Of very short period and
great power vibrating in plane transversely
with the keel records continuously by .
second pen the angles made at each moment
by the ship-that is to say, her relative inclina-
tions, as impaired by the pillows of the sea.
Another pen, actuated by rocking arm kept
level and pointing to the horizon, stimuli
taneously records the angles which the vessel
makes with the horizon or her absolute in
clinations.
The invention has been fully tested and its
fundamental principles thoroughly verified by
protracted nautical experiments. This simple
contrivance, while apparently useful only for
developing the mechanical theory of ships
rolling at sea, will doubtless subserve some Of
the most practical purposes and vital necessities
of the navigator 1t is we'll known that the COM
pass deviations on shipboard are materially
affected by the various motions of the ship
as she heels to the port or starboard side.
Late experiments as to the amount of devia-
tion Of the mysterious guide of the mariner
show conclusively that no good seaman can
fail to keep the rolling of his vessel psrpetually
in mind, and will find such an invention az
Mr.. Froude's Of incalculable value. The OBJ
servations on board the City of Baltimore by
the Committee Of the English Admiralty
proved that when the steamer was swung ten
degrees to starboard the magnetic needle
wandered from its true point twenty-five de-
grees and thirty minutes to the westward, and,
when she was heeled ten degrees to the port
side, the needle erred fifteen degrees and
three minutes to the east, making total vari-
alton of forty-one degrees of longitude due to
heeling alone without in any way changing
the direction of the ships head. These re-
suits were consistent with those of large
number of similar experiments on the different
classes Of sea-going vessels. It is also found
that ships built with their heads towards GER
tain points increase or lessen their deviation
by heeling as they go to high north or south
magnetic latitude.
But the invention to which we have called
attention will serve the additional and, if pos
sible, more important end of premonishing
vessels Of the approach of typhoons and
cyclones in the more stormy regions of the
ocean. The approach of these furious and
deadly meteors is usually announced by
swell and confusion Of the sea and the storm
waves advancing more rapidly than the storm
itself. Colonel Reid stated that when the
celebrated hurricane of 1889 occurred hs
was in Bermuda and distinctly heard the sea
breaking loudly against the south shores of
that island fully three days before the tenn
pest broke upon it. At that time the hurricane
was still within the tropic and distant ten
degrees of latitude, and as the gale neared
Bermuda the surge increased. The increase
or entire change of tides and currents or tides
earlier or later, the long and true swells, con-
fused and cross seas, raised in pyramidal and
other distinctive forms, are among the surest
premonitions of cyclone at sea; and these
premonitions by the automatic or self-register-
ing apparatus Of the English invention are
not left to the zeal and sagacity of worn-down
or unskilful master. but force themselves upon
the eye as they graphically display themselves
on the paper prepared for recording them.
This valuable contribution to nautical in
struments will be greatly valued at time
when navigation is so rapidly increasing and
careless or ignorant seamen 30 often impetil
he lives and property entrusted to them.