When Mr. Thomas L. Willson discovered the cheap process for the manufacture of carbide of calcium upon a commercial scale, and the new industry became placed upon a firm footing, it was only natural that the inventor should realize the possibilities of applying the new illuminant to the assistance of navigation. Acetylene gas gives a brilliant clear light of intense whiteness, which is capable of penetrating a great distance. Accordingly, he set to work to devise a buoy lighted by this gas, and able to carry sufficient storage of calcium carbide to burn for weeks or months without attention. When he had completed the first apparatus of this character, he handed it over to the Marine Department of the Canadian Government for submission to any test that they might consider expedient, in order to ascertain the limits of its application. The buoy was set in position and watched carefully. Periodically it was examined to ascertain whether overhauling and cleaning were necessary, as well as the behaviour of the light under all conditions of weather. Captains of vessels passing the beacon were requested to pronounce their opinions upon the quality of the light, and their remarks concerning its range, facility with which it might be picked up, reliability, and so forth, were carefully marshalled and digested by the authorities. Precisely what the officials thought of the invention is reflected most convincingly by the fact that to-day over 300 lights working upon this principle are stationed in Canadian waters, both upon the storm-bound ocean coasts and upon the wind-swept shores of the Great Lakes and waterways. [Illustration: FIG. 16.--SECTIONAL ELEVATION OF THE WILLSON AUTOMATIC FLOATING LIGHT. (See next page.)] The Willson buoys are absolutely automatic in their operation. All the impurities in the gas are removed by passing it through a special purifier, so that the burner cannot become clogged or the light impoverished. A charge of 1,300 to 1,500 pounds of carbide is carried within the apparatus, and the gas is generated _under low pressure_. The lantern is fitted with a Fresnel lens, so that the light is condensed into an intensely powerful and penetrating horizontal beam. One prominent feature is that the candle-power of acetylene gas is seven times as high as that of compressed oil-gas, while the reservoir of a given size will contain this equivalent of more light. The candle-power of these floating lights obviously varies, the largest size being capable of emitting a beam of 1,000 candle-power, this flame being the maximum that the lens will stand without breaking.