TRANSACTIONS OF SECTION G. 793 



Tessela have been built of iron, but these are found at the end of one or two years 

 to require removal from the station, docking, and the external submerged portions 

 of the hull cleaned and painted. 



Chinese gongs about two feet in diameter, sounded at short intervals, have been 

 for many years the recognised standard fog signal of light-vessels, owing probably 

 to their peculiar characteristic sound. This signal is undoubtedly distinctive and 

 serviceable at very short distances, but, like the sound of a bell, is soon dissipated 

 after leaving the immediate vicinity of the instrument. 



Many of the light-vessels of this country and other maritime nations are now 

 provided with powerful sirens or whistles, sounded by compressed air or steam. 

 Then" positions (generally at considerable distances from the shore, and in some 

 instances in fau'way channels, where the sound is radiated on all bearings) are, 

 from the imcertainty of the range of fog signals, found to be more efficient aids to 

 navigation than those installed at shore stations. 



The question of utilising lighthouses and light-vessels as signal stations in tele- 

 graphic communication with each other, and connected with a central station for 

 reporting arrivals, departures, casualties, and meteorological observations, has, 

 for some time, received the consideration of lighthouse authorities generally, and 

 among the foremost in this direction as regards lighthouses may be mentioned 

 Canada, which has a large proportion of them so arranged. In Ireland the experi- 

 ment is being made at Fastnet, a well-known exposed rock station off Cape Clear, 

 where considerable difficulties have been experienced in defending the cable from 

 the enormous wear and tear to which it is subjected at the submerged side of the 

 rock. 



During the past year experiments have been in progress by the Trinity House, 

 and I believe also by Germany, in the more difficult task of establishing telegraphic 

 communication between a light-vessel and the shore. Oft" the coast of Essex the 

 Sunk light-vessel has been so connected with the Post Office at Walton-on-the- 

 Naze, through nine miles of cable ; and, although many difficulties are being ex- 

 perienced, and the system must prove costly, ultimate success is expected. 



Very important accessories to lighthouses and light-vessels are buoys and 

 beacons. Besides indicating the navigable channels on the coast, in estuaries, and 

 in rivers, in positions where the erection of permanent beacons is frequently im- 

 practicable, they mark the position of rocics and shoals. History appears to be 

 silent as to the origin of the first buoy. Probably the piece of wood or cork for 

 buoymg and marking the position of the fisherman's net led to the primitive rude 

 buoy for marking a dangerous shoal. Buoys built ^\•ith staves of wood, and banded 

 with wrought iron hoops, have been adopted for probably over a century, and are 

 still used by all maritime nations ; but they are being rapidly superseded lay buoys 

 constructed of iron or. steel. In 1845 the first iron buoy was submitted to the 

 Trinity House by the late Mr. George W. Lenox, and since that date very great 

 improvements have been effected in the forms and construction of buoys generally, 

 owing to the ease with wliich any desired forms and dimensions can be produced 

 in iron and steel, as in shipbuilding. A very important improvement was intro- 

 duced in iron buoys in 1853 by the late Mr. George Herbert, of the Trinity House, 

 who suggested the raising up and hollowing out the bottom of buoys to about the 

 level of the plane of flotation, and the attachment of the mooring chain at a point 

 very near, but just below, the centre of gravity ; he thus secured a more uniformly 

 erect position of the buoy in a seaway and strong tidal current. The Herbert form 

 of bottom is now generally adopted. Water-tight bulkheads were early employed 

 with iron buoys for ensuring their safety. A modern ii-on or steel buoy may be, 

 and often is, cut into by the stem of a steam- vessel, or by her screw-propeller, but 

 is seldom caused to sink, its flotation being maintained by an uninjured water-tight 

 compartment. The immunity from sinking, under such circumstances, of these 

 ii'on or steel floating bodies, with their heavy iron mooring chain attached, is 

 suggestive of an important requirement of the present day, viz., an unsinkable 

 passenger steam-vessel. In the interests of humanity, no more important question 

 than this could engage the attention of engineers, and certainly none more deserv- 

 ing of the best efforts of modern mechanical science. With the rapid increase in 



