19th Century Sikess Hygrometer

In the United Kingdom, the Sikes hydrometer was, during the second half of the 19th century and the beginning of the 20th century, the official instrument for verifying the alcohol content of drinks for commercial transactions and during the collection of taxes. The hydrometer, in gilded brass, is accompanied by nine overloads marked 10 in 10, from 10 to 90. These are notched discs which can be placed above the lower bulb of the instrument thus modifying its weight and therefore its position balance at immersion. The distance between two consecutive discs is equivalent to the 10 major divisions of the upper stem of the hydrometer. So, everything comes down to considering that the device offers a graduation ten times larger than the one it actually carries. This makes it possible to cover the entire scale of alcohol concentrations. These surcharges bear, on the back, a number identical to that which appears on the different parts of the hydrometer. A tenth overload in the shape of a small hollow cylinder and called a cap can be plugged into the end of the upper, graduated rod. This additional overhead is used for checking the aerometer. The verification consists of immersing the instrument, fitted with its cap and the disc marked 60, in distilled water whose temperature is 51° Fahrenheit. The flush level must be the mark P engraved on the edge of the graduated rod near division 1 of the reading scale. If we remove the cylindrical overload to leave only the disc marked 60, the hydrometer immersed in a 57% alcoholic solution, always at the same temperature of 51°F, should lead to the same outcrop. This solution of 57% alcohol in water is called "proof spirit": it is the basis from which future concentrations are expressed. All these details come from the Compendium site, where photos await you. Magnificent item in its original box.