What is "ballasts"

Usage examples of "ballasts".

Rob's interest in the beauties of Nature could not compete with his fascination for pipes, cables, caissons, pulleys and ballasts.

The tree outside, as he arose, looked fatter, as if it had taken on invisible ballasts in the night.

On the second blast of the diving klaxon, the air vents in the ballasts tanks had been opened, and the sea had roared into the space between the ship’s two hulls.