From about 1299 Lubeck presided over a league of cities, Wismar, Rostock, Stralsund, Greifswald and some smaller ones, and this Hansa of towns became heir to a Hansa of traders simultaneously on the eastern and the western sea, after Lubeck and her confederates had been admitted to the same privileges with Cologne, Dortmund and Soest at Bruges and in the steelyards of London, Lynn and Boston.
Unequal-armed balances may be divided into (I) balances consisting of a single steelyard; (2) balances formed by combinations of unequal-armed levers and steelyards, such as platform machines, weighbridges, &c.
Steelyards are simple, trustworthy and durable, but unless special contrivances are introduced for ascertaining the position of the travelling poise with very great accuracy, there will be a little uncertainty as to the reading, and therefore steelyards are not in general so accurate as scale-beams. When carefully nicked they are well-adapted for weighing out definite quantities of goods, such as i lb, 2 lb, &c., as in such cases there is no question of estimation.
Steelyards, like other weighing machines, will be " accelerating," or " vibrating " according to the arrangement of the knife-edges.
Steelyards, again, are frequently arranged as counter machines, having a scoop or pan resting on a pair of knife-edges at the short end, which is prevented V P FIG.
Steelyards are largely used in machines for the automatic weighing out of granular substances.
Some of the largest and most accurate steelyards are those made for testing machines for tearing and crushing samples of metals and other materials.
Platform machines, like steelyards, may be arranged either on the " accelerating " principle or on the " vibrating " principle.