Page:Popular Science Monthly Volume 88.djvu/479



NE wreck a day is said to be the average on the fog-visited Pacific Coast. Commerce on the Great Lakes, while possible during only half the year, is exposed to dangers inherent in waters visited by dense and persistent fog. Likewise, the Atlantic Coast is not without this menace to navigation, for it runs a close second to the Pacific in the number of its sea tragedies; the Gulf of Mexico is also frequently blanketed with mist, and there the dangers of collision or grounding on coral reef or sand bank are much increased.

The United States lighthouse service has greatly lessened the death toll of treacherous points, but even a beacon of a million candlepower or the shrillest fog whistle is powerless to combat fog. Sound, unreliable under even the best atmospheric conditions, is refracted and reflected to a marked degree by fog-banks, fog-waves and fog-billows. Fog blots out the bright rays from a lighthouse as completely as if it were swathed in thickest wool, and the mariner who is unfortunate enough to find himself on the sea under these conditions, unable to sight a warning beacon, and not trusting fog-siren or booming rocket, flounders about as helplessly as a blind man on a busy street. Fog is without doubt the greatest menace to safety known to navigation, and any means of enabling a mariner to keep his course in fog and to receive timely warning of the proximity of other vessels will relieve ocean travel of its chief danger.

Scientists in the United States, thoroughly cognizant of this fact, have for some time been on the trail of devices calculated to overcome this peril of the sea, but not until recently have practical suggestions been put forward for the relief of this age-old menace.

The "radio compass," which promises to add much to the safety of navigation, has been in use in Europe for several years. It is said that ships have found their way up the river to Hamburg in the densest fog, and that Zeppelins depend entirely on stations fitted with this special apparatus during darkness or when the earth and its familiar land-