PHILOSOPHICAL SOCIETY OP WASHINGTON. IGY 



observed for several years past on the coast of Maine, which has 

 been classed among those to which the term " abnormal phe- 

 nomena of sound" is applied. In August, 1813, this was par- 

 tially examined, and the result published in the Light-House 

 Report for 1874. In order to investigate it further, I associated 

 myself with Gen. J. C. Duane, Engineer of the 1st Light-House 

 District; Commander H. F. Picking, Inspector of the same Dis- 

 trict; Mr. Edward L. Woodruff, Assist. Engineer of the 3d Dis- 

 ti'ict; and Mr. Chas. Edwards, Asst. Engineer of the 1st District. 



The phenomenon to be investigated was exhibited in connec- 

 tion with the fog-signal at a station called White-Head, on the 

 coast of Maine, at the entrance of Penobscot Bay ; it was 

 reported as having been frequently observed by the captains of 

 the steamers plying between Boston, and New Brunswick, and 

 had also been witnessed on two different occasions by officers of 

 the Light-House Establishment. 



The phenomenon, as reported by these authorities, consisted in 

 hearing the sound of a ten-inch whistle distinctly as the station 

 is approached, till within the distance of from four to six miles, 

 then losing it through a space of about three miles, and not hear- 

 ing it again until within about a quarter of a mile of the instru- 

 ment, when it suddenly becomes audible almost in its full power. 



This phenomenon, according to the statement of the keeper of 

 the light-house station, is noticed whenever the vessel is ap- 

 proaching the station from the southwest, and the wind is in the 

 same direction. It is especially observed during a fog, when the 

 warning of the signal is most wanted, and which in this locality 

 is always accompanied by a wind from the south or southwest. 



Our first object was to verify the phenomenon, and for this 

 purpose we steamed to the southwest, directly against the wind, 

 which was blowing at the time at about the velocity of ten miles 

 per hour ; this fortunately happened to be the direction of the 

 wind during which the phenomenon was most frequently observed. 

 The whistle was sounded every minute by an automatic arrange- 

 ment, and the time at which the several blasts were given could 

 be noted from the vessel by the puffs of steam emitted by the 

 whistle. As we increased our distance from the signal, the sound 

 very slightly diminished in loudness, until the distance was about 

 a half mile, when it suddenly ceased to be heard, and continued 

 inaudible for about a mile farther, when it was faintly heard and 



