ated air within expelled. On the deck are also a derrick and a powerful sand pump for use in wrecking or in Submarine construction, while a powerful electric lamp in her conical under-water how illuminates the field of her operations. Most interesting is the sea door at the bottom forward, through which divers enter and leave the boat when on the ocean floor, the inrush of water into the diving compartment being prevented in the meantime by air pressure within, equal to and balancing the water pressure without. The 'Argonaut' has already traveled, it is said, hundreds of miles on the surface and scores on the ocean
bottom. She can remain at the bottom as long as her gasoline and provisions hold out, with no other inconvenience to her crew than is occasioned by the somewhat restricted room within.
Mastery is the motto of mankind. Instinctively the race is ever obedient to that ringing commission of the Omnipotent: "Replenish the earth, and subdue it—and have dominion." Man longs to explore every unknown realm. He thirsts for knowledge, which is power, and by it he masters the mighty forces of nature and makes them his servants. It seems a little thing to have dominion over the habitable por-
