RESEAECHES IN SOUND. 493 



miles of the scene of action witli a force intended to attack tlie flank of 

 the Northern forces, and although listening attentively for the sound of 

 the commencement of the engagement, the battle, which was a severe 

 one, and lasting about three hours, ended without his having heard a 

 single gun. (See Johnston's report.) Another case of a similar kuid 

 occiu-red to General McOlellan at the battle of Gaines' Mills, June 27, 

 18G2, also near Richmond. Although a sharj) engagement was progress- 

 ing within three or four miles for four* or live hours, the general and his 

 staff were unaware of its occurrence, and when their attention was 

 called to some feeble sound they had no idea that it was from anything 

 more than a skirmish of little importance. (See Eeport of the Commit- 

 tee on the Conduct of the War.) A third and perhaps still more re- 

 markable instance is given in a skirmish between a part of the Second 

 Corps under General Warren and a force of the enemy. In this case 

 the sound of the firing was heard more distinctly at General Meade's 

 headquarters than it was at the headquarters of the Second Corj^s itself, 

 although the latter was about midway between the former and the point 

 of conflict. Indeed the sound api^eared so near General Meade's camp 

 that the mipression was made that the enemy had gotten between it and 

 General Warren's command. In fact so many instances occurred of wrong 

 imi)ressious as to direction and distance derived from the sound of guns 

 that little rehauce came to be placed on these indications. 



In the report of a series of experiments made under the direction of 

 the Light-House Board by General Duaue of the Engineer Corps is the 

 following remark : " The most perplexing difficulty arises from the fact 

 that the fog-signal often appears to be surrounded by a belt varying in 

 radius from one to one and a half miles. Thus in moving directly from 

 a station the sound is audible for the distance of a mile, is then lost for 

 about the same distance, after which it is again distinctly heard for a 

 long time." 



Again, in a series of experiments at which Sir Frederick Arrow and Cap- 

 tain Webb, of the Trinity Board, assisted, it was found that in passing in 

 the rear of the opposite side of an island in front of which a fog-signal 

 was placed, the sound entirely disappeared, but by going fui'ther oft" to 

 the distance of two or three miles it reappeared in full force, even with 

 a large island inters^ening. Again, from the experiments made under the 

 immediate direction of the present chairman of the Light-House Board, 

 with the assistance of Admiral Powell and Mr. Lederle, the light- 

 house engineer, and also from separate expeiiments made by General 

 Duane, it appears that while a reflector, in the focus of which a steam 

 whistle or ordinary bell is jflaced, reinforces the sound for a short dis- 

 tance, it produces little or no effect at the distance of two or three miles, 

 and, indeed, the instrument can be as well heard in still air at the dis- 

 tance of four or five miles in the line of the axis of the reflector, whether 

 the ear be placed before or behind it. From these results we would 

 infer that the lateral divergency of sound, or its tendency to spread lat- 



