This simple bit of mechanism has saved us from being crushed flat by the ice on more than one occasion.
The destruction of a ship between two ice floes is not sudden, like her destruction by a submarine mine, for instance.

It is a slow and gradually increasing pressure from both sides, sometimes till the ice meets in the vitals of the ship.

A vessel might stay thus, suspended between two floes, for twenty-four hours--or until the movement of the tides relaxed the pressure, when she would sink.

The ice might open at first just sufficiently to let the hull go down, and the ends of the yards might catch on the ice and break, with the weight of the water-filled hull, as was the case with the ill-fated _Jeannette_.

One ship, in the Gulf of St.Lawrence, was caught in the ice and dragged over the rocks like a nutmeg over a nutmeg grater.