1877] WRITINGS OF JOSEPH HENRY. 



491 



Our next operation at this place (the principal object of 

 our excursion) was the examination of the remarkable ab- 

 normal phenomenon, which has been frequently observed 

 by the captains of the steamers plying between Boston and 

 New Brunswick, and has also been noticed on two different 

 occasions bj' officers of the light-house establishment. The 

 phenomenon, as reported by these authorities, consists in 

 hearing the sound distinctly (on approaching the station) at 

 the distance of from six to four miles, then losing it through a 

 space of about three miles, and not hearing it again until with- 

 in about a quarter of a mile of the instrument, when it be- 

 comes suddenly audible in almost full power. This phenom- 

 enon is always noticed when the vessel is approaching the 

 signal from the south-west, and the wind is in the same or in 

 a southerly direction, and therefore opposed to the direction 

 of the sound from the station, as is usually the case during a 

 fog. Commander Picking, having frequently received com- 

 plaints from masters of vessels as to losing the sound at this 

 place, concluded to verify the facts by his own observation. 

 For this purpose, he embraced the opportunity of an inspec- 

 tion-tour in July, 1877, to approach the station from the 

 southwest during a fog. In his own words, he heard the 

 sound distinctly through a space of from six to four miles, 

 then lost it, and could hear nothing until within a quarter 

 of a mile of the station, when the bla3t of the whistle burst 

 forth in full sound. The wind at this time was from the 

 southward, or against the sound. This cessation in the 

 hearine: of the sound could not have been due to the failure 

 of the instrument to emit sound, since its operation is auto- 

 matic when once started, and in this case the fog so lifted on 

 nearing the station as to admit the observation of the puffs 

 of steam emitted at each blast of the whistle. 



On a previous occasion General Duane and Mr. Edwards 

 on approaching the same signal from the south-west heard 

 the sound at about six miles distance, then lost it, and did 

 not again hear it until within about a quarter of a mile. 

 The wind in this instance was also the same as that in the 

 observation of Commander Picking, namely from the south- 

 west. 



