A Dutch philosopher at Leyden, having observed that excited electrics soon lost their electricity in the open air, especially when the air was full of moisture, conceived the idea that the electricity of bodies might be retained by surrounding them with bodies which did not conduct it; and in 1745 the Leyden jar was invented, which led to the knowledge that the force of electricity could be extended through an indefinite circuit.

Instead of the hot, stuffy interior of the submarine with its pale electrics and maze of machinery, he was gazing at a wide circle of small-crested waves which shone gloriously blue under a brilliant sky.

Sinking down into the grass, we were so intent upon the sharp electric signaling as to be oblivious to aught else, until a voice rang a harsh challenge from behind.