| 摘要 |
<p>A balance, for example a letter scales, comprises an articulated parallelepiped formed by two upright plates pivotally joined by two transverse plates. One of the upright plates is fixed on a base and the other, which is movable against the action of a spring, carries a scale at its upper end. The lower transverse plate has an extension carrying a pivotally mounted arm which in turn pivotally carries an index at a free end thereof. A pair of upright members on the frame define a vertical guide channel for the free end and for the index which cooperates with graduations on one of the members.</p> |
