a steelyard. This seems to have been an
invention of Italy: according to Isidore (Orig.
was first used in Campania, and was called trutina
and it may be remarked that in Roman remains
generally the steelyard is the commonest form of weighing machine
discovered. There can be no doubt that the balance [LIBRA
] was a far older contrivance than the
steelyard: Blümner (in Baumeister's
p. 2078) conjectures as the primitive
form a simple bar of wood placed through a ring or loop with the articles to
be weighed against each other hung at the two ends. The more elaborate
balance was a natural improvement on this, but the steelyard clearly
involved more ingenuity and calculation.
An account of the steelyard will be found in Vitruvius, 10.3
. The parts defined are the
beam or yard (scapus
) suspended by a hook or
chain which is called the handle (ansa
this is the point of revolution (centrum
near it is the caput,
from which depends the
): on the other side of the
is marked with points (puncta
), which express the weight of objects in the scale as the
or hanging weight, moves
along the beam. This aequipondium was generally adorned with a head divine,
human or animal.
Statera. (From Museum at Rome.)
The example here given is from the Museum of the Capitol at Rome. Others
differ in having less ornament; and it is common also to find a hook
attached to the shorter arm between the centrum
and the caput,
which was intended to hold
articles whose size and shape made it convenient to hang them on, instead of
putting them in the scale, and, as this altered the leverage, there was a
double set of puncta
on the beam to suit either
arrangement. A third kind is shown in Baumeister (Denkm.
2316), where a weight hangs on one arm of an ordinary balance, this arm
being marked with puncta.
It is clear that this
was intended for use either as libra
in the former case the weight
would be detached; in the latter one scale would be detached (or allowance
made for it in the puncta
), and the other would
be used as in the steelyard.
It must be observed that, though statera
strictly the steelyard, it is often used for a weighing machine of any kind:
e. g. in Suet. Vesp.
25, the statera
of the dream is clearly a balance with two scales; so
also the aurificis statera
is doubtless a balance of
a peculiarly delicate kind contrasted with the popularis
or less carefully adjusted balance; for trutina
is used for any weighing machine, without
distinction of form. (An illustration of this goldsmith's balance from an
ancient relief is shown in Blümner, Technologie,
The engraving in this article shows various weights (aequipondia,
), such as may be seen in many
museums, and of which a large collection may be studied in the British
Museum. There was at Rome a special guild of Sacomarii,
makers of weights (C. I. L.
713). For a marble altar set up by a guild of
Sacomarii at Ostia, see Lanciani, Ancient Rome,