| 摘要 |
The balance beam of a scale is provided with a series of notches. A poise, preferably a metal ball, is movable along the balance beam to be set in one of the notches and retained there without clamping. A secondary counterpoise on the other side of the pivot of the scale beam from the primary poise is comprised of the slider of a vernier. The vernier scale on the slider uses slits instead of the usual lines as graduations so the vernier body serves as a mask about the slits. There are stationary graduations on the beam. The slider has a window through which the numbers indicative of the unit weight graduations on the beam are read. Tenths of units and even hundredths of units can be read using the vernier scale. The slit on the vernier scale that is filled in the background by a graduation on the beam is the pertinent unit value to be read. In one embodiment, background unit graduations appear in three consecutive slits and it is always the nominal middle of the three slits that is filled and is to be read when there are partially filled slits to the left and the right of the pertinent slit. The masked vernier can also be used on other measuring instruments that have a fixed scale over which the vernier scale translates.
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