An ordinary ship could have made no headway whatever.
Wardwell, the chief engineer, stood his eight-hour or twelve-hour watch the same as his assistants, and during the passage of these dangerous channels he was nearly always in the engine-room, watching the machinery to see that no part of it got out of order at a crucial moment--which would have meant the loss of the ship.

When we were between two big floes, forcing our way through, I would call down the tube leading from the bridge to the engine-room: "Chief, you've got to keep her moving until I give you word, no matter what happens." Sometimes the ship would get stuck between the corners of two floes which were slowly coming together.

At such a time a minute is an eternity.

I would call down the tube to Wardwell, "You've got to jump her now, the length of fifty yards," or whatever it might be.

And I could feel the ship shaking under me as she seemed to take the flying leap, under the impulse of live steam poured directly from the boilers into the fifty-two-inch low-pressure cylinder.
The engines of the _Roosevelt_ have what is called a by-pass, by which the live steam can be turned into the big cylinder, more than doubling the power of the engines for a few minutes.