What is "rampart grenades"

Grenade \Gre*nade"\, n. [F. grenade a pomegranate, a grenade, or Sp. granada; orig., filled with seeds. So called from the resemblance of its shape to a pomegranate. See Carnet, Grain a kernel, and cf. Pomegranate.] (Min.) A hollow ball or shell of iron filled with powder of other explosive, ignited by means of a fuse, and thrown from the hand among enemies. Hand grenade.

1. A small grenade of iron or glass, usually about two and a half inches in diameter, to be thrown from the hand into the head of a sap, trenches, covered way, or upon besiegers mounting a breach.

2. A portable fire extinguisher consisting of a glass bottle containing water and gas. It is thrown into the flames. Called also fire grenade.

   Rampart grenades, grenades of various sizes, which, when used, are rolled over the pararapet in a trough.