544 RESEARCHES IN SOUND. 



When the buoy rises, the water in the cylinder by its inertia retains 

 its position, and a partial vacuum is formed between the head of the 

 column and the diaphragm, into which the air is drawn through two of 

 the tubes, and when the buoy descends, the escape through the injec- 

 tion-tube being prevented by valves, it is forced out of the inner tube 

 and actuates the wliistle. 



The mooring-chain, which is sixty fathoms in length, is attached to 

 the cylinder at a point just below the buoy, and is secured to a large 

 stone weighing about six tons. The apparatus rides peri)endicularly. 



The sound in this instrument is not i^roduced merely by the difference 

 in hydrostatic pressure of the water in the two j)Ositions of the buoy, 

 but by the accumulated effect of impulse generated by the motion of 

 the apparatus. 



Plans have been devised, but have not yet been perfected, to condense 

 the air in the buoy by the effect of repeated oscillations, until a valve 

 loaded to a definite i^ressure would open automatically and allow the air 

 to escape. In this way the sound from the accumulated pressure would 

 be produced at intervals to a greater or less extent, and would serve to 

 diversify the character of the sound so as to enable the mariner to dis- 

 tinguish different locations. . The invention, as. it is, is considered a 

 valuable ad<lition to tlie aids to navigation, has received the unqualified 

 approbation of all navigators on this coast who are acquainted with its 

 operation, and will probably be introduced in all countries where its 

 merits are known. Experience has shown that it can be permanently 

 moored in deep water, and that vessels can safely approach it within the 

 nearest distance, and t9;ke perfect departure from it. 



The Light-House Board has adopted this buoy as one of its permanent 

 aids to navigation, and will iu time introduce it at all points where its 

 presence will be of importance to the navigator. In order to obtain 

 reliable data as to the ox)erations of the automatic buoy, Commander 

 Picking has established a series of observations at all the stations in the 

 neighborhood of the buoys, giving the time of hearing it, the direction 

 of the wind, and the state of the sea, from which it appears that in the 

 month of January, 1877, one of these buoys was heard every day at a 

 station one and one-eighth miles distant ; every day but two at one two 

 and one-quarter miles distant ; fourteen times at one seven and one-half 

 miles distant, and four times at one eight and one-half miles distant. 

 It is heard by the pilots of the New York and Boston steamers at dis- 

 tances of from one-fifth to five miles, and has been frequently heard by 

 the inspector of the first light-house district at a distance of nine miles, 

 and even, under the most favorable circumstances, fifteen miles. 



We sailed around the buoy and observed the difference in the intensity 

 of sound in regard to the direction (tf the wind, which was at the time 

 a fresh breeze of from twelve to fifteen miles per hour, from the west- 

 ward, the greatest intensity being apparently at points forty-five degrees 

 on either s:'de of the axis of the wind. The effect however was not 

 very definitely marked, though the sound on the whole appeared to be 



