were also made with different pattern of trumpets, including forms
having elliptical sections, the long axis being placed vertically.
The conclusions of the committee may be briefly summarized as
follows: (1) When a large arc requires to be guarded two fixed
trumpets suitably placed are more effective than one large trumpet
capable of being rotated. (2) When the arc to be guarded is larger
than that effectively covered by two trumpets, the mushroom-head
trumpet is a satisfactory instrument for the purpose. (3) A siren
rotated by a separate motor yields better results than when self-driven.
(4) No advantage commensurate with the additional power
required is obtained by the use of air at a higher pressure than 25 ℔
per sq. in. (5) The number of vibrations per second produced by
the siren or reed should be in unison with the proper note of the
associated trumpet. (6) When two notes of different pitch are
employed the difference between these should, if possible, be an
octave. (7) For calm weather a low note is more suitable than a
high note, but when sounding against the wind and with a rough and
noisy sea a high note has the greater range. (8) From causes which
cannot be determined at the time or predicted beforehand, areas
sometimes exist in which the sounds of fog signals may be greatly
enfeebled or even lost altogether. This effect was more frequently
observed during comparatively calm weather and at no great distance
from the signal station. (It has often been observed that the sound
of a signal may be entirely lost within a short distance of the source,
while heard distinctly at a greater distance and at the same time.)
(9) The siren was the most effective signal experimented with; the
reed-horn, although inferior in power, is suitable for situations of
secondary importance. (No explosive signals were under trial
during the experiments.) (10) A fog signal, owing to the uncertainty
attending its audibility, must be regarded only as an auxiliary aid
to navigation which cannot at all times be relied upon.
Submarine Bell Signals.—As early as 1841 J. D. Colladon conducted experiments on the lake of Geneva to test the suitability of water as a medium for transmission of sound signals and was able to convey distinctly audible sounds through water for a distance of over 21 m., but it was not until 1904 that any successful practical application of this means of signalling was made in connexion with light-vessels. There are at present (1910) over 120 submarine bells in service, principally in connexion with light-vessels, off the coasts of the United Kingdom, United States, Canada, Germany, France and other countries. These bells are struck by clappers actuated by pneumatic or electrical mechanism. Other submerged bells have been fitted to buoys and beacon structures, or placed on the sea bed; in the former case the bell is actuated by the motion of the buoy and in others by electric current, transmitted by cable from the shore. In some cases, when submarine bells are associated with gas buoys or beacons, the compressed gas is employed to actuate the bell striking mechanism. To take full advantage of the signals thus provided it is necessary for ships approaching them to be fitted with special receiving mechanism of telephonic character installed below the water line and in contact with the hull plating. The signals are audible by the aid of ear pieces similar to ordinary telephone receivers. Not only can the bell signals be heard at considerable distances—frequently over 10 m.—and in all conditions of weather, but the direction of the bell in reference to the moving ship can be determined within narrow limits. The system is likely to be widely extended and many merchant vessels and war ships have been fitted with signal receiving mechanism.
The following table (V.) gives the total numbers of fog signals of each class in use on the 1st of January 1910 in certain countries.
Table V.
| Sirens. | Diaphone. | Horns, Trumpets, &c. |
Whistles. | Explosive Signals (tonite, &c.). |
Guns. | Bells. | Gongs. | Submarine Bells. |
Totals. | ||
| Power. | Manual. | ||||||||||
| England and Channel Islands | 44 | .. | 27 | 31 | 2 | 15 | .. | 48 | 10 | 16 | 193 |
| Scotland and Isle of Man | 35 | .. | 6 | 2 | .. | 5 | .. | 16 | 3 | .. | 67 |
| Ireland | 12 | .. | 2 | 6 | .. | 11 | 3 | 11 | .. | 3 | 48 |
| France | 12 | .. | 7 | 1 | .. | 1 | .. | 25 | .. | 2 | 48 |
| United States (excluding inland | |||||||||||
| lakes and rivers) | 43 | .. | 35 | 15 | 59 | .. | .. | 218 | 1 | 36 | 407 |
| British North America (excluding | |||||||||||
| inland lakes and rivers) | 6 | 66 | 5 | 79 | 16 | 8 | .. | 24 | .. | 11 | 215 |
When two kinds of signal are employed at any one station, one being subsidiary, the latter is omitted from the enumeration. Buoy and unattended beacon bells and whistles are also omitted, but local port and harbour signals not under the immediate jurisdiction of the various lighthouse boards are included, more especially in Great Britain.
11. Lighthouse Administration. The principal countries of the world possess organized and central authorities responsible for the installation and maintenance of coast lights and fog signals, buoys and beacons.
United Kingdom.—In England the corporation of Trinity House, or according to its original charter, “The Master Wardens, and Assistants of the Guild Fraternity or Brotherhood of the most glorious and undivided Trinity and of St Clement, in the Parish of Deptford Strond, in the county of Kent,” existed in the reign of Henry VII. as a religious house with certain duties connected with pilotage, and was incorporated during the reign of Henry VIII. In 1565 it was given certain rights to maintain beacons, &c., but not until 1680 did it own any lighthouses. Since that date it has gradually purchased most of the ancient privately owned lighthouses and has erected many new ones. The act of 1836 gave the corporation control of English coast lights with certain supervisory powers over the numerous local lighting authorities, including the Irish and Scottish Boards. The corporation now consists of a Master, Deputy-master, and 22 Elder Brethren (10 of whom are honorary), together with an unlimited number of Younger Brethren, who, however, perform no executive duties. In Scotland and the Isle of Man the lights are under the control of the Commissioners of Northern Lighthouses constituted in 1786 and incorporated in 1798. The lighting of the Irish coast is in the hands of the Commissioners of Irish Lights formed in 1867 in succession to the old Dublin Ballast Board. The principal local light boards in the United Kingdom are the Mersey Docks and Harbour Board, and the Clyde Lighthouse Trustees. The three general lighthouse boards of the United Kingdom, by the provision of the Mercantile Marine Act of 1854, are subordinate to the Board of Trade, which controls all finances.
On the 1st of January 1910 the lights, fog signals and submarine bells in service under the control of the several authorities in the United Kingdom were as follows:
| Light- houses. | Light- vessels. | Fog Signals. | Submarine Bells. | |
| Trinity House | 116 | 51 | 97 | 12 |
| Northern Lighthouse Commissioners | 138 | 5 | 44 | .. |
| Irish Lights Commissioners | 93 | 11 | 35 | 3 |
| Mersey Docks and Harbour Board | 16 | 6 | 13 | 2 |
| Admiralty | 31 | 2 | 6 | .. |
| Clyde Lighthouse Trustees | 14 | 1 | 5 | .. |
| Other local lighting authorities | 809 | 11 | 89 | 2 |
| Totals | 1217 | 87 | 289 | 19 |
Some small harbour and river lights of subsidiary character are not included in the above total.
United States.—The United States Lighthouse Board was constituted by act of Congress in 1852. The Secretary of Commerce and Labor is the ex-officio president. The board consists of two officers of the navy, two engineer officers of the army, and two civilian scientific members, with two secretaries, one a naval officer, the other an officer of engineers in the army. The members are appointed by the president of the United States. The coast-line of the states, with the lakes and rivers and Porto Rico, is divided into 16 executive districts for purposes of administration.
The following table shows the distribution of lighthouses, light-vessels, &c., maintained by the lighthouse board in the United States in June 1909. In addition there are a few small lights and buoys privately maintained.
| Lighthouses and beacon lights | 1333 |
| Light-vessels in position | 53 |
| Light-vessels for relief | 13 |
| Gas lighted buoys in position | 94 |
| Fog signals operated by steam or oil engines | 228 |
| Fog signals operated by clockwork, &c. | 205 |
| Submarine signals | 43 |
| Post lights | 2333 |
| Day or unlighted beacons | 1157 |
| Bell buoys in position | 169 |
| Whistling buoys in position | 94 |
| Other buoys | 5760 |
| Steam tenders | 51 |
| Constructional Staff | 318 |
| Light keepers; and light attendants | 3137 |
| Officers and crews of light-vessels and tenders | 1693 |
France.—The lighthouse board of France is known as the Commission des Phares, dating from 1792 and remodelled in 1811, and is under the direction of the minister of public works. It consists of four engineers, two naval officers and one member of the Institute, one inspector-general of marine engineers, and one hydrographic engineer. The chief executive officers are an Inspecteur Général des Ponts et Chaussées, who is director of the board, and another engineer of the same corps, who is engineer-in-chief and secretary. The board has control of about 750 lights, including those of Corsica, Algeria, &c. A similar system has been established in Spain.
