Page:Popular Science Monthly Volume 6.djvu/718

698 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 distance 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. 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 obliterate 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