It is easy to read your weight on a digital scale, but the older models of physician's scales, called "beam balance scales," require you to do a little work and a tiny bit of math. These scales work on the lever principle. The beam of the balance is fixed on a pivot. You move weights along one side of the beam until it balances and is level. When the beam is level, the position of the weights shows your weight.
Move all the weights to zero. This will be on the left side of the marked bar they are attached to. Be sure they are seated in a slot. This ensures they are stable and will not move.
Step onto the scale gently. Stand still with your weight distributed evenly on both feet. The end of the beam at the far left of the scale should rise to the top of its frame. It will usually hit the top with a distinct bump.
Move the large sliding weight to the right from notch to notch. The end of the beam, sticking out on the left side of the scale, will lower as you move the weight. Stop moving the weight when it falls below the horizontal mark in the center of its frame. Then move the large weight back to the next notch on the left. The beam should again be above the mark.
Move the small sliding weight slowly to the right until the end of the balance beam is level with the mark on the frame. The beam should be level and balanced. When you move, the beam will move slightly above and below the level mark.
Add the number of the large weight to the number of the small weight to determine your weight. For example, if the large weight is on 150 pounds and the small weight is on 36 pounds, your weight is 186 pounds.