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).
Z scale
Z scale was introduced by the German model train manufacturer Märklin in 1972 at the Nuremberg Toy Fair. It was the brainchild of Helmut Killian, Märklin's head design engineer at the time. The letter "Z" was chosen to designate the new scale, its place as the last character of the German and English alphabets signaling the thought that there would never be a smaller commercial model railway scale. While there have been attempts since then to bring even smaller scales to the market, they remain niche products without a wider followingthe largest market being T gauge (1:450, gauge), designed in Japan and manufactured in China.