722 



SOUND-SIGNALS. 



Bell-BuoySt The bell-boat, which is at most 

 a clumsy contrivance, liable to be upset in 

 heavy weather, costly to build, hard to handle, 

 and difficult to keep in repair, has been super- 

 seded by the Brown bell-buoy, which was in- 

 vented by the officer of the lighthouse estab- 

 lishment whose name it bears. The bell is 

 mounted on the bottom section of an iron buoy 

 6 feet 6 inches across, which is decked over 

 and fitted with a framework of 3-inch angle- 

 iron 9 feet high, to which a 300-pound bell is 

 rigidly attached. A radial grooved iron plate 

 is made fast to the frame under the bell 



FIG. 2. BROWN'S BELL-BUOY. 



and close to it, on which is laid a free cannon- 

 ball. As the buoy rolls on the sea, this ball 

 rolls on the plate, striking some side of the 

 bell at each motion with such force as to cause 

 it to toll. Like the whistling-buoy, the bell- 

 buoy sounds the loudest when the sea is the 

 roughest, but the bell-buoy is adapted to shoal 

 water, where the whistling-buoy could not 

 ride ; and, if there is any motion to the sea, the 

 bell-buoy will make some sound. Hence the 

 whistling-buoy is used in roadsteads and the 

 open sea, while the bell-buoy is preferred in 

 harbors, rivers, and the like, where the sound- 

 range needed is shorter, and smoother water 

 usually obtains. In July, 1883, there were 24 

 of these bell-buoys in United States waters. 



They cost, with their fitments and moorings, 

 about $1,000 each. 



Locomotive-Whistles. It appears from the evi- 

 dence given in 1845, before the select commit- 

 tee raided by the English House of Commons, 

 that the use of the locomotive- whistle as a fog- 

 signal was first suggested by Mr. A. Gordon, 

 C. E., who proposed to use air or steam for 

 sounding it, and to place it in the focus of a 

 reflector, or a group of reflectors, to concen- 

 trate its sound into a powerful phonic beam. 

 It was his idea that the sharpness or shrill- 

 ness of the whistle constituted its chief value. 

 And it is conceded that Mr. C. L. Daboll, un- 

 der the direction of Prof. Henry, and at the in- 

 stance of the United States Lighthouse Board, 

 first practically used it as a fog-signal by erect- 

 ing one for use at Beaver Tail Point, in Narra- 

 gansett Bay. The sounding of the whistle is 

 well described by Price-Edwards, a noted Eng- 

 lish lighthouse engineer, " as caused by the vi- 

 bration of the column of air contained within the 

 bell or dome, the vibration being set up by the 

 impact of a current of steam or air at a high 

 pressure." It is probable that the metal of the 

 bell is likewise set in vibration and gives to 

 the sound its timbre or quality. It is noted 

 that the energy so excited expends its chief 

 force in the immediate vicinity of its source, 

 and may be regarded, therefore, as to some ex- 

 tent wasted. The sound of the whistle, more- 

 over, is diffused equally on all sides. These 

 characteristics to some extent explain the im- 

 potency of the sound to penetrate to great 

 distances. Difference in pitch is obtained by 

 altering the distance between the steam orifice 

 and the rim of the drum. When brought close 

 to each other, say within half an inch, the sound 

 produced is very shrill, but it becomes deeper as 

 the space between the rim and the steam or air 

 orifice is increased. 



Prof. Henry says the sound of the whistle is 

 distributed horizontally. It is, however, much 

 stronger in the plane containing the lower edge 

 of the bell than on either side of this plane. 

 Thus, if the whistle is standing upright in the 

 ordinary position, its sound is more distinct in 

 a horizontal plane passing through the whistle 

 than above it, or below. 



The steam fog-whistle is the same instru- 

 ment ordinarily used on steamboats and loco- 

 motives. It is from 6 to 18 inches in diame- 

 ter, and is operated by steam under a pressure 

 of from 50 to 100 pounds. An engine takes 

 its steam from the same boiler, and by an au- 

 tomatic arrangement shuts off and turns on the 

 steam by opening and closing its valves at de- 

 termined times. The machinery is simple, the 

 piston-pressure is light, and the engine requires 

 no more skilled attention than does an ordinary 

 station-engine. 



"The experiments made by the Trinity House 

 in 1873-'74seem to show," Price-Edwards says, 

 "that the sound of the most powerful whistle, 

 whether blown by steam or hot air, was gen- 

 erally inferior to the sound yielded by other 



