RESEARCHES IN SOUND. 505 



position in the lower bay of iSTew York, and perhaps still more fortunate 

 in the season of the year when, on account of the lieat of the sun, a land 

 and sea breeze, which changed its direction at a particular hour of the 

 day, enabled results to be obtained bearing especially on the phenomena 

 to be investigated. 



Attention was first given to the character of the several steam-whistles 

 which were intended to be used as the sources of the sound during the 

 series of investigations. 



These whistles, which were sounded during the whole of the observa- 

 tions with 20 pounds of steam on each boiler, gave at first discordant 

 sounds, and were found b}" their effect upon an artificial ear to be con- 

 siderably different in penetrating power; they were then adjusted by 

 increasing or diminishing the space between the bell and the lower cylin- 

 der by turning a screw on the axis of the bell intended for that purpose, 

 until they produced the same effect upon the sand in the membrane of 

 the artificial ear; but in order to further be insured of the equality of 

 the penetrating power of the several whistles, the three steamers abreast, 

 forming as it were a platoon, were directed to proceed against the wind, 

 sounding all the time m regular succession — the Cactus first, then, after 

 an interval of a few seconds, the Mistletoe, and then the Putnam — until 

 the stationary observers lost the sound of each. Thej" became inaudible 

 all very nearly at the same moment. The sound of the Putnam was 

 thought to be slightly less disti^pt; it was therefore chosen as a station- 

 ary vessel, from which the observations of the sound of the other two 

 were to be made. 



The Putnam being anchored at the point before mentioned, arrange- 

 ments were made for sending off the other two vessels in opposite direc- 

 tions, one with and the other against the wind, with instructions to retiu'u 

 when the sound became inaudible to those on the stationary vessel, this 

 to be indicated by a flag-signal. It should be mentioned that the velocity 

 of the wind was ineasured from time to time during the subsequent ex- 

 periments with one of Eobinson's hemispherical cup anemometers, made 

 by Casella, of London. The velocity of the wind first observed by this 

 instrument, just before the starting of the vessels, was 6 miles i^er hour, 

 the instrument being freelj" exposed on the paddle-boxes of the steamer. 

 A sensitive aneroid barometer marked 30.395 in. and continued to rise 

 gradually during the day to 30.43 in. the temperature was 71° F. 



The vessels left at 11:18 a. m. the wind being from the west, Captain 

 Davis taking charge of the sounding of the whistle on the Cactus, which 

 proceeded east with the wind, the sound coming to the ear of the observer 

 against the wind; while the sounding on the Mistletoe was in charge of 

 General Woodruff", and, as the vessel steamed against the wind, the sound 

 came to the observers on the stationary vessel with the wind ; the other 

 members of the party remained on the Putnam, at anchor at the point 

 before mentioned, off the Hook, Major Hains having charge of the sig- 

 < nals. The sound of the first of the vessels was heard faiutlv at 14 min- 



