weighing-machines for family use. These are found to have existed among
the ancients, and must, at a very early age, have been both publicly and
privately employed for the regulation of quantities. The modern English
weights were adjusted by the 27th chapter of Magna Charta, or the great
charter forced, by the barons, from King John at Runnymede, in Surrey.
Therein it is declared that the weights, all over England, shall be the
same, although for different commodities there were two different kinds,
Troy and Avoirdupois. The origin of both is taken from a grain of wheat
gathered in the middle of an ear. The standard of measures was
originally kept at Winchester, and by a law of King Edgar was ordained
to be observed throughout the kingdom.
[Illustration: _Fig_. 19.]
[Illustration: _Fig_. 20.]
Fig. 19 is an ancient pair of common scales, with two basins and
a movable weight, which is made in the form of a head, covered
with the pileus, because Mercury had the weights and measures
under his superintendence. It is engraved on a stone in the
gallery of Florence. Fig. 20 represents a modern
weighing-machine, of great convenience, and generally in use in
those establishments where a great deal of cooking is carried
on.