sound signals be- have, as far as their hearers are concerned, in a most erratic manner. In some cases the Lighthouse Board gets indignant complaints that on a certain date a cer- tain fog signal was silent when it should have sounded. Investigation shows that the signal was sounding at assume he… … be evolved, and some method discovered for their correction, as the variations of the compass are corrected, then sound may be depended upon as a ble to the very ship it was meant to reach. Naturally, more definite and accurate aid to navigation.” Prof. such instances have been very carefully…
Internet Archive · Public domain (published before 1931). Free to use for anything.
