Schermuly

A Schermuly was a projectile weapon that fired a rocket and a line. James Skinsale found one in Fang Rock lighthouse and, despite not knowing its exact nature, carried it up to the lamp gallery, hoping to use it against the Rutan scout. The Fourth Doctor identified it as an early Schermuly and decided that it would be ineffective and opted to create a makeshift mortar instead. (TV: Horror of Fang Rock)