Sikes Hydrometer, Complete With Original Weights And Thermometer. This complete and original Sikes Hydrometer was made by Luftus 146 Oxford Street, Londin. The set is signed with a serial number 11460 and includes an ivory thermometer by J. Long London, float, 10 weights and Mahogany case. This is a brass instrument set used to determine the strength of spirits providing an accurate method of determining alcohol proof, strength, and percentages. Sikes's hydrometer was enshrined in legislation in 1816 with the Sikes Hydrometer Act and remained the legal standard until 1907.