Page:Popular Science Monthly Volume 88.djvu/479

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Experimental Electricity

Practical Electrical Hints for the Amateur Wireless Communication

��Safeguarding Vessels by Radio

By Annis Salsbury

��ONE wreck a day is said to be the average on the fog-visited Pacitic 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 col- lision 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 light- house as completely as if it were swathed in thickest wool, and the mar- iner who is unfortunate enough to find himself on the sea under these condi- tions, 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, thor- oughly 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 de- pend entirely on stations fitted with this special apparatus during darkness or when the earth and its familiar land-

��Loop oena/:faf nghf ang/ei

���Wiring diagram of the BelUni-Tosi di- rectional receiver

��451

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