Beam Balance

The triple beam balance is used to measure masses very precisely; the reading error is 0.05 gram.
With the pan empty, move the three sliders on the three beams to their leftmost positions, so that the balance reads zero. If the indicator on the far right is not aligned with the fixed mark, then calibrate the balance by turning the set screw on the left under the pan.
Once the balance has been calibrated, place the object to be measured on the pan.
Move the 100 gram slider along the beam to the right until the indicator drops below the fixed mark. The notched position immediately to the left of this point indicates the number of hundreds of grams.
Now move the 10 gram slider along the beam to the right until the indicator drops below the fixed mark. The notched position immediately to the left of this point indicates the number of tens of grams.
The beam in front is not notched; the slider can move anywhere along the beam. The boldface numbers on this beam are grams and the tick marks between the boldface numbers indicate tenths of grams.
To find the mass of the object on the pan, simple add the numbers from the three beams.
As with a ruler, it is possible to read the front scale to the nearest half tick mark.