To read a specific gravity meter, or hydrometer, place the specific gravity meter in the liquid with the bulb facing downward, and note the number that is at the meniscus. In most containers, the surface of the liquid is curved. The bottom of that curve is the meniscus.
It's important to make sure that the hydrometer is clean before putting it into the liquid. Additionally, carefully spinning the hydrometer dislodges any bubbles that have attached to the surface. Bubbles distort hydrometer readings by causing the meter to float higher in the liquid than it should. It is also important to choose a specific gravity meter that is ideal for the liquid to be measured. For example, a urinometer is a specific gravity meter used for urinalysis.