The U.S.S. Minneconsin steamed out of New York harbor and headed down toward the lower bay. On her forward deck rested a huge globe. The bottom quarter of the sphere was made of some dark opaque substance but the upper portion was transparent as crystal. Through the walls could be seen a quantity of apparatus resting on the opaque bottom portion. Two mechanics from the Bureau of Standards were making final adjustments of one of the pieces of apparatus, which resembled a tank 343 fitted with a piston geared to an electric motor. From the tank, tubes ran to four hollow pipes, an inch and a half in diameter, which ran through the skin and extended thirty inches from the outer skin of the twenty-foot sphere. Dr. Bird stood near talking with the executive officer of the ship and from time to time giving a brief word of direction to the mechanics.
“It’s safer than you might think, Commander,” he said. “In the first place, that globe is not made of ordinary glass; it is made of vitrilene, a new semi-malleable glass which was developed at the Bureau and which is being made on an experimental scale for us by the Pyrex people. It is much stronger than ordinary glass, and is not sensitive to shock. It is also perfectly transparent to ultra-violet light, being superior even to rock crystal or fused quartz in that respect. The walls, as you have noticed, are four inches thick, and I have calculated that the ball will stand a uniform external pressure of thirty-five hundred atmospheres, the pressure which would be encountered at a depth of about twenty miles. I believe that it will stand a squeeze of six thousand tons without buckling, and it is impossible to fracture it by shock. It could be dropped from the top of the Woolworth Building, and it would just bounce.”
“It seems incredible that it could stand such a pressure as you have named.”
“My figures are conservative ones. Lambertson calculated them even higher, but we allowed for the fact that this is the first large mass of the material to be cast, and lowered them.”
“But suppose your lifting cable should break?” objected the naval officer. “The outfit weighs a good many tons.”
“You notice that the lower quarter is made of lead. The specific gravity of the entire globe when sealed up tight with two men in it is only a little more than unity. In the water its weight is so little that a three-inch manilla hawser would raise it, let alone a steel cable. I have another safety device. Granted that the cable should snap, I can detach the lead from it and it would shoot to the surface like a rocket.”
“How long can you remain under water in it?”
“A week, if necessary. I have an oxygen tank and a carbon dioxide removing apparatus which will keep the air in good condition. The globe is electrically lighted, and can be heated if necessary. Should my telephone line become fouled and broken, I have a radio set which will enable me to communicate with you. I can’t see that it is especially dangerous; not nearly as much so as a submarine.”