Lights at Sea.

Hastings Standard, Issue 309, 29 April 1897, Page 4

Lights at Sea.

The penetrating powers and ranges of powerful lights, such as are employed in lighthouse service, rapidly decrease as tfie ratio of their luminous power increases, For instancs, a light of 500,000 candlepower in the British Channel has, in average weather, a luminous range of about forty-four nautical miles, while if the light be increased to the power of 1,000,000 candle the luminous range is only five miles more, or 41) miles. According to current practices, lights up to 200,000 candle-power are obtained by means of mineral oil lamps, while electric lights are used for higher powers, and almost any power may thus be obtained. The' highest power yet attempted is about 30,000,000, at Penmark Point, in the department of Finisterre, France, which, when completed, will be the most powerful lighthouse illumination in the word. The height of the tower in which it is to be located is about sixty-three metres, enabling it to be seen during the day from a distance of eighteen miles in fine weather. During the night this light will be visible for sixty miles. The rotundity of the earth will prevent the rays frcm striking the eye directly at a distance of more than thirty miles, but the sky overhead will appear illuminated for thirty miles more. The estimated cost is about 120,000d01s. — Machinery.