SOUND-SIGNALS AT SEA. 93 



which would take up out of the water the signals arriving from 

 neighboring vessels. As boys in swimming communicate the 

 sound of the striking of stones together under water, so is it pos- 

 sible to send musical tones from one ship to another. 



For steamships the sound-producing apparatus was designed 

 to be a steam fog-horn or whistle, specially constructed to sound 

 under water, and to be heard at least from six to eight miles. 

 From the nature of its tone it would be easily distinguishable 

 from other sounds always more or less present under water, 

 such as from breakers, waves, etc. With such whistles a Morse 

 alphabet of long and short blasts and pauses was to provide a 

 means of extended communication, while a simple universal 

 code would indicate a ship's course. Since ignorance of the very 

 presence of a ship, rather than incorrect estimates of her course, 

 has been the principal cause of ocean collisions, the simple hear- 

 ing of the sound would prove a most excellent general safe- 

 guard. Bell-buoys were to have a second bell added under 

 water, while lightships, lighthouses, and any headlands might 

 also be provided with submerged bells which could be rung 

 from the shore, when necessary. Sailing-craft, both large and 

 small, would have bells ; and, since an ordinary locomotive-bell 

 can be heard, according to experiments, at least two miles under 

 water, these simple means would seem to afford sufficient limits 

 for protection for such vessels. 



As to the receiving apparatus, with which each vessel was to 

 be provided : The original plan of 1883, and which has not been 

 changed, was to employ some form of telephone acting as a trans- 

 mitter under water, and connected with a receiver within the 

 vessel. The surface of the transmitter exposed to the water, 

 and which must receive the sound-waves, should be protected 

 against ice, barnacles, heavy waves, etc. One design was : One 

 or more vertical pipes in different parts of a ship were to extend 

 from the vessel's interior through the hull, near the keel, and be 

 open to the free admission of water at their lower ends ; their 

 upper ends were to extend within the vessel a little way above 

 the keel, and were to be plugged, so that the water could not 

 overflow into the vessel. These pipes would then provide col- 

 umns of water always still, and would communicate directly 

 with the water outside. Sound would then enter and pass 

 up these pipes, and would encounter microphonic transmitters 

 placed suitably in them. Wires from the transmitters would 

 run to a small room secladed where convenient in the ship, 

 away from disturbing noises, and here telephone receivers would 

 be placed, and observers stationed here in night or fog. 



For small craft, it was found that a pipe shaped much like a 

 powder-horn, with a thin, flexible membrane stretched tightly 



