1874] WRITINGS OP JOSEPH HENBY. 435 



On the southerly side of this island a light-house is about 

 being erected, and a siren station had been established at 

 this locality, and was in full operation. 



There are here two sirens attached to one boiler, one to be 

 used in case of an accident to the other. For the sake of 

 experiment they are of slightly different qualities, one with 

 a larger trumpet with a revolving disk of the old pattern, 

 giving a lower tone; the other a smaller trumpet having a 

 revolving disk with openings allowing a much more sudden 

 and full blast of steam, and revolving with greater velocity so 

 as to give a higher pitch. The latter is far the superior instru- 

 ment, as was evident to us by the sound which it produced, 

 and as had been established by the use of the artificial ear 

 in the manufactory of Mr. Brown. The effect on the 

 unguarded ear was scarcely endurable, and the very earth 

 around appeared to tremble during the blast. The keeper 

 (an intelligent man who has been promoted from the posi- 

 tion of assistant keeper at Beaver Tail light to this station) 

 informed us that a fleet of fishing- vessels coming in, dis- 

 tinctly heard it at a distance estimated by their rate of sail- 

 ing at scarcely less than thirty miles; this was on two sepa- 

 rate occasions. The keeper had -been directed to note and 

 record the date at which he heard the sound from other 

 signals; he reported that he had frequently heard the fog- 

 signal at Point Judith, a distance of seventeen miles, and 

 that the observer at the latter place frequently heard his 

 signal ; but on comparing records, the two sounds had not 

 been heard simultaneously by the two keepers; when a sound 

 was heard from one station, the opposite sound was not 

 heard from the other, illustrating again the general rule 

 that sound is not transmitted simultaneously with equal 

 intensity in opposite directions. 



This occasion also furnished very favorable conditions for 

 observing the remarkable phenomenon of the ocean-echo. 

 At the cessation of each blast of the trumpet, (after a slight 

 interval,) a distinct and prolonged echo was returned from the 

 un-obstructed ocean. It is important to observe — in regard 

 to this phenomenon, that the siren is placed near the edge 



