Alcoholic spirits measure
Alcoholic spirits measures are instruments designed to measure exact amounts or shots of alcoholic spirits.
The most common products used today to measure spirits are the thimble measure and the non-drip measure, often referred to as an optic. The terms Optic, Optic Pearl, OpticJade and OpticOpal are all trademarks of Gaskell & Chambers owned by the company IMI Cornelius (UK) Ltd, but the word “optic” has become synonymous with inverted or non-drip spirit measures.
The optic or non-drip measure is mounted beneath an inverted spirit bottle, whereby the alcohol dispenses into the measure and is discharged when a lever on the measure is pushed up. This mechanism ensures that a correct spirit measure can be dispensed each time, as the inverted bottle allows the measure to be replenished in the optic after each shot has been dispensed. Bottles are available to the trade with their labels upside down so that they will be the right way up when mounted on the optic.
The thimble measure is a stainless steel vessel, like a shot glass, predominantly used as a measurement with free flow pourers.
United Kingdom
The Weights and Measures Act of 1963 made it illegal in Britain for businesses to give short weights or short measures to consumers. Before this there was no legislation, only guidelines as to the correct weight of an alcoholic spirit measure, and if spirit measures or optics were used, they required a government stamp to certify that the measure was accurate. The 1963 Act formalized the legal measures by which spirits and other alcoholic beverages should be dispensed, namely 1/4 gill (35.5 ml), 1/5 gill (28.4 ml) or 1/6 gill (23.7 ml) although this has now been replaced by 25ml and 35ml for single measures with landlords being able to decide which quantities they dispense.
The legal capacity for thimble measures is 25ml or 35ml for single spirits and 50ml or 70ml for double spirit measures. Either capacity can be used, the difference being caused by historically larger measures being used in Scotland. Thimble measures also used in 175ml and 250ml volumes for measuring wine. Although government stamped for the correct volume, the thimble measure does rely on the user measuring the spirit out manually into the thimble.