698 THE POPULAR SCIENCE MONTHLY. 



against the sound. On the Dover side, and at about a mile and a half 

 from the Foreland, we first heard the faint but distinct sound of the 

 siren. The horn-sound was inaudible. A gun fired during our halt 

 was also unheard. 



As we approached the Foreland we saw the smoke of the gun. Mr. 

 Edwards heard a faint crack, but neither Mr. Douglas nor I heard 

 any thing. The sound of the siren was, at the same time, of piercing 

 intensity. We waited for ten minutes, when another gun was fired. 

 The smoke was at hand, and I thought I heard a faint thud, but could 

 not be certain. My companions heard nothing. On pacing the dis- 

 tance afterward, we were found to be only 550 yards from the gun. 

 We were shaded at the time by a slight eminence from both the siren 

 and the gun, but this could not account for the utter extinction of the 

 gun-sound at so short a distance, and at a time when the siren sent to 

 us a note of great power. 



Mr. Ayres, at my request, walked to windward along the cliff, 

 while Mr. Douglas proceeded to St. Margaret's Bay. During their 

 absence I had three guns fired. Mr. Ayres heard only one of them. 

 Favored by the wind, Mr. Douglas, at twice the distance, and far 

 more deeply immersed in the sound-shadow, heard all three reports 

 with the utmost distinctness. 



Joining Mr. Douglas, we continued our walk to a distance of three- 

 quarters of a mile beyond St. Margaret's Bay. Here, being dead to 

 leeward, though the wind blew with unabated violence, the sound of 

 the siren was borne to us with extraordinary power. 1 In this position 

 we also heard the gun loudly, and two other loud reports at the proper 

 interval of ten minutes, as we returned to the Foreland. 



It is within the mark to say that the gun to-day was heard five 

 times, and might have been heard fifteen times as far to leeward as to 

 windward. 



In windy weather the shortness of its sound is a serious drawback 

 to the use of a gun as a signal. In the case of the horn and siren, 

 time is given for the attention to be fixed upon the sound ; and a 

 single puff, while cutting out a portion of the blast, does not oblit- 

 erate it wholly. Such a puff, however, may be fatal to the momentary 

 gun-sound. 



On the leeward side of the Foreland, on the 23d, the sounds were 

 heard at least four times as far as on the windward side, while in both 

 directions the siren possessed the greatest penetrative power. 



On the 24th the wind shifted to east-southeast, and the sounds, 

 which, when the wind was west-southwest, failed to reach Dover, were 

 now heard in the streets through thick rain. On the 27th the wind 

 was east-northeast. In our writing-room, in the Lord Warden Hotel, 

 in the bedrooms, and on the staircase, the sound of the siren reached 



1 The horn here was temporarily suspended, but doubtless would have been well 

 heard. 



