I am merely appreciating an admirable piece of mechanical design most efficiently carried out.

Observe the completeness of the thing, and the way in which all the necessities of the case are foreseen and met.

This projectile was discharged from a powerful air-gun--the walking-stick form--provided with a force-pump and key.

The barrel of that gun was rifled." "How do you know that ?" I asked.
"Well, to begin with, it would be useless to fit a needle to the projectile unless the latter was made to travel with the point forwards; but there is direct evidence that the barrel was rifled.

You notice the little square projection on the back surface of the cylinder.