A set of wooden forms, such as spheres, cubes, pyramids, cones, cylinders, and similar, but truncated, forms, can be obtained at any school supply store.
If Tom shut off all power, coasted for a moment, and then, ere the propeller had ceased revolving, if he could start the motor on the spark, the silent cylinders might pick up, with the others, and begin again.
The captain repeatedly called for more steam, which the engineer refused to furnish, cautiously keeping the pressure low because the salt water foamed in the boilers and some of it passed over into the cylinders, causing heavy thumping at the end of each piston stroke, and threatening to knock out the cylinder-heads.