The SIKES hydrometer is a precision instrument used to measure the density of liquids, particularly in alcohol production. Invented by Bartholomew Sikes in the 19th century, this device determines the alcohol concentration of a solution by floating it in the liquid. The hydrometer is calibrated with specific markings that indicate the relative density, making it easy to calculate the alcohol content. Even today, the Sikes hydrometer is valued for its accuracy and remains a valuable tool in distilleries and laboratories.