Weighing scale
The balance (also balance scale, beam balance and laboratory balance) was the first mass measuring instrument invented. In its traditional form, it consists of a pivoted horizontal lever with arms of equal lengththe beamand a weighing pan suspended from each arm (hence the plural name ""scales" for a weighing instrument). The unknown mass is placed in one pan and standard masses are added to the other pan until the beam is as close to equilibrium as possible. In precision balances, a more accurate determination of the mass is given by the position of a sliding mass moved along a graduated scale. Technically, a balance compares weight rather than mass, but, in a given gravitational field (such as Earth's gravity), the weight of an object is proportional to its mass, so the standard masses used with balances are usually labeled in units of mass (e.g. g or kg).
Russell A. Kirsch
In 1957, Kirsch's group developed a digital image scanner, to “trace variations of intensity over the surfaces of photographs”, and made the first digital scans. One of the first photographs scanned, a picture of Kirsch’s three-month-old son, was captured as just 30,976 pixels, a 176 × 176 array, in an area measuring 5 cm × 5 cm. The bit depth was only one bit per pixel, stark black and white with no intermediate shades of gray, but by combining several scans made using different scanning thresholds, grayscale information could also be acquired. They used the computer to extract line drawings, count objects, recognize alphanumeric characters and produce oscilloscope displays. Kirsch also proposed the Kirsch operator for edge detection.