scale, in weights and measures, instruments for determining weight, generally for other than laboratory use. For the principles of operation of all weighing devices, see balance. Platform scales utilize a succession of multiplying levers that transmit the weight to a beam or other registration device. They are used where massive objects or large quantities are to be weighed. For example, a railway car or truck moves onto a platform scale before and after unloading or loading, in each case the difference between the weighings being the weight of its cargo. As the name implies, counter scales are used in commercial establishments where weighing can be most conveniently done on a counter. Cylinder, drum, or barrel scales show their calibrations on a rotatable chart. These find wide use because of the ease with which the cost of a given weight may be read from them through the juxtaposition of fixed and rotating charts. The same purpose is served by the fan-type scale, in which an indicator moves through an arc marked from zero to the maximum capacity of the scale. Both the indicator and the fan expanse are calibrated for automatic computation. A great variety of scales are specially constructed for industrial uses in which weighing of a continuous flow of material is required. The scale in such cases is part of the machinery that carries the weighed material to a succeeding operation. Many scales provide printed records of each reading, and some keep a cumulative registration of a succession of readings.
See A. W. Green, How We Weigh and Measure (1961); B. Kisch, Scales and Weights (1965).