Canadian Tribal-class destroyers used this mechanical fire control computer to help direct their powerful batteries of 4.7-inch quick firing guns.

The Dumaresq Mark VIII was a compact, manually adjusted computer that calculated the relative courses and speeds of a ship and its target, indicating their changes of position with respect to each other. Various components were moved and adjusted to input information on courses and speeds, while pointers provided data to help aim guns. The version of the device seen here was a key part of the fire-control system that made Canadian destroyers potent surface combatants.

Range Finder, Dumaresq Mk VIII
CWM 19700010-001