The Probert Encyclopaedia of General Information

BALLAST

Ballast is a term applied to heavy matter, such as stone, sand, iron, or water placed in the bottom of a sailing ship or other vessel to sink it in the water to such a depth as to enable it to carry sufficient sail without oversetting. The term ballast is also applied to the sand placed in bags in the car of a hot-air balloon to steady it and to enable the aeronaut to lighten the balloon by throwing part of it out. Ballast is also the name for the material used to fill up the space between the rails on a railway in order to make it firm and solid.
Research Ballast