What is the definition of a triple beam balance?

A triple beam balance is an instrument used to obtain precise measurements of masses. The reading error of a standard triple beam balance is only 0.05 grams.

A triple beam balance has a pan on which users place objects to weigh and three beams that each have a slider. When the pan is empty and the sliders are placed at the leftmost position, the balance should have a reading of zero. When measuring an object's mass, the 100-gram slider is moved to the right until the indicator falls below the zero mark. The slider is then moved back a notch. Then, the same process is repeated with the 10-gram slider and the 1-gram slider to arrive at the object's mass.