"Merely by a reference to the Navy List. But look ahead; see that object dead in line with our bows?"
"An electro-contact mine, by Jove!" exclaimed Hythe.
"Right again. Since the beginning of this German war-scare, which I venture to predict will pass away, unless my powers of reasoning play me false, the approaches to all British ports of any magnitude, especially the naval ones, have been strewn with these contrivances. Watch."
A slight touch on the switch controlling the helm and the "Aphrodite" swung away to starboard, clearing the deadly mine by less than twenty feet. Another loomed up ahead, only to be avoided by another touch of the helmsman’s finger.
"I do not want to boast," remarked Captain Restronguet, "but I have enough electrical energy stored within this vessel to explode simultaneously every mine, be it a mechanical, observation, or electro-contact one, in Plymouth Sound, and even seriously imperil every fort and ship in the vicinity. Some day I may have to put the powers at my command to a stern test, but until the necessity actually arises I prefer to exploit the ’Aphrodite’ solely as an example of what I am capable of producing in the interests of science. Look out of that scuttle on your left; what do you see?"
"A regular pile of huge stones," replied the sub.
"The eastern extremity of that wonderful work known as Plymouth Breakwater. We are now in only forty-five feet of water allowing for the state of the tide. The top of our conning-towers are but fifteen feet above the surface, yet I can assert with confidence that anyone standing on Staddon Heights and looking down upon this channel from an altitude of not less than three hundred and fifty feet would not see the faintest sign of the ’Aphrodite.’"
"What causes her to be almost invisible?" asked Hythe. "Are her plates made of or faced with glass?"
"Oh, no. Glass would not serve the purpose. The light would be reflected too much. In fact the ’Aphrodite’ would be a huge heliograph, sending out rays of reflected sunlight in all directions. The composition placed over the steel plating of this submarine is a secret. All I can say at present is that it has the power to reflect the image of near objects only. It absorbs all brilliant rays of light, and is in consequence an almost perfect form of invisibility."