twice as good a conductor of electricity as aluminum, four times

as strong, and is the lightest of all known metals, having a

specific gravity of only two, which last property will be of

great use to you, for of course the more weight you have to

propel the more apergetic repulsion you will have to develop."

"I will get some drawing-paper I left outside in my trap," said

Ayrault, "when with your ideas we may arrive at something

definite," saying which, he left the room.