submarine bell could be heard on coming in range of it. If
the tone was louder on the starboard side than on the port,
the mariner would know that the light-vessel was on his star-
board side, and if the tone was exactly the same in both
microphones, he would know that the light-vessel was dead
ahead.

It was found that, even in the case of vessels to which the
sound-receiving microphones had not been fitted, a listener,
putting his ear to the inner surface of the plating-say, in
the empty forepeak below the water-line-could hear the
sound proceeding from a submarine bell several miles away;
but under such circumstances no information is derived as
to the direction from which the sound proceeds, and hence
a vessel encompassed in fog could not be steered by bell and
must suffer a denial of those advantages that come from the
knowledge of direction that is derivable on board of vessels
in which suitable instruments have been installed to receive
the sounds.

The substantial service rendered to shipping by the sub-
marine bells first established decided the United States
Lighthouse Board to extend their installation from time to
time to other light-vessels until at present forty-six of the
light-vessels in the waters of the United States are thus
equipped, and the signals which they send out are of un-
doubted aid to deep-water navigation.

Equally effective as aids to navigation are the submarine
bells that have been fitted to buoys, where they are worked
by the motion of the sea, and those that have been sus-
pended from tripods on the sea-bottom, where they are con-
trolled electrically from shore-stations and serve to give
warning of dangers or to mark turning-points along the
routes of commerce.

Many of the light-vessels and buoys in European waters
have been similarly furnished with these bells, and they
have been likewise established in the region of the Gulf of
St. Lawrence; and, as the effective range of the submarine
bell far exceeds that of aerial sound-signals, having been known
to exceed fifteen miles, and their bearing can be determined
with sufficient accuracy for safe navigation in fog, if a vessel
is equipped with receivers, it has seemed appropriate to set
forth for the benefit of mariners a list of the stations where
they are at present established.

List of Stations sending Submarine Signals in Canada and
the United States.

LIGHT-VESSELS.

CANADA:

St. Lawrence River,-
Red Island .. 3
White Island .. 5
Princes Shoal .. 7
Gulf of St. Lawrence,-
Anticosti .. 15
Nova Scotia,-
Lurcher Shoal .. 14
UNITED STATES:-
Atlantic Coast,
Cape Elizabeth .. 74
Boston .. .. 54
Pollock Rip Shoal .. 73
Pollock Rip .. 5
Great Round Shoal 2
Hedge Fence
Nantucket Shoals .. 66
Relief vessel No. 66
Hen and Chickens .. 86
Vineyard Sound .. 7
Brenton Reef .. 39
Cornfield Point .. 48
Fire Island .. 68
Sandy Hook
Relief vessel No. 78
Relief vessel No. 16
Ambrose Channel .. 22
North-east End
Five Fathom Bank 42
Overfalls .. .. 69

List of Stations sending Submarine Signals in Europe.

ENGLAND:-
Light-vessels-
Outer Dowsing ... 4
Tongue ... 4
East Goodwin .. 6
Royal Sovereign .. 3
Shambles ... 5
Owers ... 7
Outer Gabbard ... 7
Spurn .... 3
Shore-stations, Hand-
bell,-
Queenboro Pier ..
Bell Buoys,-
Dean Tail, Nab Rock
GERMANY:-
Light-vessels,-
Amrumbank ... 66
Elbe Island ... 4
Ausenweser ... 5
Ausenjade .. 222
Norderney .. 3
Borkumriff .. 9
Ausseneider .. 9
Kiel ...
Fehmarn .. 9
Aldergrund ...
Ostsee ...
Weser II ..

HOlLAND:-
Light-vessels,-
Terschellingen .. 3
Haaks ... 1
Maas ... 1
Schowen Bank
N. Hinder .. 2
W. Hinder I .. 5
W. Hinder II
Shore-stations, Hand-
bell,-
Vlissingen Pier
Bell Buoys,-
Ymuiden ..
FRANCE:-
Light-vessels,-
Sandettie .. 31
Shore-stations,-
Havre (pneumatic
bell)
Bell Buoys,-
Havre Buoy
Tenders,-
Cherbourg, N. G.L.
"Willkommen" 99
SWEDEN:-
Light-vessels,-
Trelleborg .. 1
DENMARK:-
Light-vessels,-
Gjedser .. .. 1

The number in the column headed "Code" indicates the
signal which is rung by the submarine bell for the purpose
of identifying the light vessel or station to which it is
attached. For example, the submarine bell on Heald Bank
light-vessel, off the coast of Texas, will sound, during thick
and foggy weather, the number 22 at regular intervals, thus:
Two strokes in quick succession followed, after a silent in-
terval of three seconds, by two more strokes in quick suc-
cession, and then a silent interval of five seconds.

Remarkable endurance-tests have been applied to some of
these submarine signaling-installations. From a cottage at
Point Allerton, near Boston, in which a 24-horse power oil-
engine operated an electric generator, a submarine cable was
laid to the shore, and thence two miles out into the
harbour along the sea-bottom. At the end of the cable was
an iron tripod standing on the bottom of the ocean, 70ft.
below the surface of the water, and on the tripod was a bell
weighing 220 lb., the clapper of which was actuated by
powerful magnets. On 30th March, 1907, the current was
turned on and the bell began to strike at the rate of about
22 blows a minute, and continued until 16th May, when the
total number of strokes had reached 1,032,930 in a duration
of 7894 hours.

The pneumatic bells on five light-vessels were also required
to be rung continuously, night and day, for sixty-one days,
making a period equal to two years and a half of service
according to the highest demands made in past years upon
the fog-whistle on the light-vessel at Sandy Hook. Sub-
marine-bell buoys have also been tested. The fact that the
bearing of the buoy can be found in fog or at night makes
them advantageous to shipping when they are placed in
exposed positions in water of sufficient depth to give the
vessels steering for them sufficient space to manoeuvre for the
purpose of locating the origin of the sound. It is noted that
in restricted waters, or when the bell is located near steep
banks or rocky shores, an echo may be expected; and this
fact requires that the proposed location should, in each case,
be thoroughly investigated by experiment, because there are
possible situations where the echo may be heard instead of the
direct sound, and thus lead to an erroneous determination of
the place of the danger which the bell is intended to mark.

The mechanism for submarine-bell buoys is dependent on
wave-motion for its power, and therefore differs from that of
the electrically controlled tripod bell, and also from the
pneumatic bell employed in connection with light-vessels.
On the trunk or stem of the buoy is a float or "sea-anchor,"
free to move up and down for a short distance and ballasted
so as to have, as nearly as may be, the same weight as sea-
water. It is the design that this shall remain practically
stationary as the buoy rises and falls. The pull-rod of the
clapper is connected to a crank on a toothed wheel which
is turned by a ratchet-and-pawl gear operated by two arms
attached to the sea-anchor. Of special interest in connec-
tion with submarine-signal buoys are the gas buoys which
have been experimentally fitted with bells that are rung
through mechanism actuated by the pressure of the gas sup-
plied for the light, and are thus independent of the action of
the waves as an agency for ringing the bell, and consequently
free of the liability to irregularity in the intervals between
the strokes of the clapper, which precludes the successful
ringing of a code-signal.

Fenwick Island Shoal 3
Thirty-five Foot Chan-
nel .. .. 45
Cape Charles .. 49
Relief vessel No. 45
Tail of the Horseshoe 6
Diamond Shoal .. 5
Cape Lookout Shoal 46
Frying-pan Shoal .. 1
Relief vessel No. 53 53
Brunswick Bar .. 84
South Pass .. 43
Heald Bank .. 22
Relief 91, Winter
Quarter Shoal ..
Pacific Coast,-
Umatilla Reef .. 67
San Francisco .. 7
Blunts Reef .. 83
Relief vessel No. 76
Columbia River .. 88
Great Lakes,-
Eleven Foot Shoal 53
Lansing Shoal .. 3
Grays Reef .. 5
White Shoal .. 22
Poe Reef .. 5
Lake Huron .. 5
Bar Point Shoal .. 3
South-east Shoal .. 1

ELECTRIC SHORE-STATIONS.

CANADA:-
Cape Forchu, Yar-
mouth .. .. 2
Nova Scotia-
Louisburg .. 2
Chebucto Head, Hali-
fax .. .. 4
New Brunswick-
Negro Head, St John 3
UNITED STATES :-
Detour, Michigan ..

BELL BUOYS.

CANADA:-
Egg Island ..
Sambro Island ..
Lunenburg ..