88 x 85 x 20
Carved inlayed wood and brass
INDEX 1788 : F.III.113
Statera composita ex duabus stateris simul arte conjunctis: Aequipondia quinque, ex orichalco: et Machina lignea ex pluribus partibus formata, cui appenditur haec statera.
Balance comprising two balances equally and artistically united. Five brass counterbalances and one wooden machine made of various parts from which this balance is suspended.
This model of the steelyard from the Gabinete de Física in Coimbra, is composed of an assemblage of two levers the lower lever being inter-resistant and the higher one inter-fixed.
The body which is to be weighed is suspended on the lower lever by a hook. The end of this lever is attached to the inter-fixed lever by another hook: the group is balanced by a sliding weight on the bigger arm of the inter-fixed lever.
The steelyard is mounted on a richly carved wooden frame, which gives it a magnificent appearance.
With this set of levers it was possible to balance extremely heavy bodies with very light weights. According to dalla Bella this type of balance, the so-called "Dutch balance" , was used to weigh bells, anchors and military weapons for throwing projectiles. The multiplication power of the apparatus depends on the relations between the lengths of the arms of the two levers.
From Colégio dos Nobres, catalogue n.º 105.
´s Gravesande, Willem Jacob, Physices Elementa, Leiden, 1742, § 295, Tab. XI, Fig. 2.