“Colonel Lysander Stark stopped at last before a low door, which he unlocked. Within was a small, square room, in which the three of us could hardly get at one time. Ferguson remained outside, and the colonel ushered me in.

“ ‘We are now,’ said he, ‘actually within the hydraulic press, and it would be a particularly unpleasant thing for us if anyone were to turn it on. The ceiling of this small chamber is really the end of the descending piston, and it comes down with the force of many tons upon this metal floor. There are small lateral columns of water outside which receive the force, and which transmit and multiply it in the manner which is familiar to you. The machine goes readily enough, but there is some stiffness in the working of it, and it has lost a little of its force. Perhaps you will have the goodness to look it over and to show us how we can set it right.’