Very rare English 18thc powder tester eprovette with brass frame and mahogany grip. The brass shutter incorporates a number-graduated brass wheel dial and when powder in the touch-hole and barrel is ignited, is forced round and held by means of a tensioned spring. The strength of the powder is then noted by how far the wheel is rotated and the powder strength can then be adjusted to suit by re-testing until correct. This item is unusual in shape and is in very good working condition. Overall length 23cms.