Page:On the various forces of nature and their relations to each other.djvu/179

Rh the better be enabled to illustrate that which I look forward to as the higher mode of lighting, by means of the electric lamp and the lime light.

There is nothing more simple than a candle being set down in a cottage window to guide a husband to his home; but when we want to make a similar guide on a large scale, not merely over a river or over a moor, but over large expanses of sea, how can we then make the signal, using only a candle? I have shewn in this diagram (fig. 55) what we may imagine to be the rays of a candle of any other source of light emanating from the