Page:Popular Science Monthly Volume 7.djvu/438

422 a long time. This action is common to all ear-signals, and has been at times observed at all the stations, at one of which the signal is situated on a bare rock twenty miles from the main-land, with no surrounding objects to affect the sound."

It is not necessary to assume here the existence of a "belt," at some distance from the station. The passage of an acoustic cloud over the station itself would produce the observed phenomenon.

Passing over the record of many other valuable observations, in the Report of General Duane, I come to a few very important remarks which have a direct bearing upon the present question:

The Report of General Duane is marked throughout by fidelity to facts, rare sagacity, and soberness of speculation. The last three of the paragraphs just quoted exhibit, in my opinion, the only approach to a true explanation of the phenomena which the Washington Report reveals. At this point, however, the eminent chairman of the Lighthouse Board strikes in with the following criticism:

I have already cited the remarkable observation of General Duane, that, with a snow-storm from the northeast blowing against the sound,