Shape of Pivots
Pivots must be hard, round and well polished; their shoulders are to be flat, not too large, with ends well rounded off, so that they do not wear the cap jewel. The jewel holes must be round, smooth and not larger than is requisite for the free motion of the pivot which is surrounded with oil. Their sides must be parallel to those of the pivots, so that they sustain pressure of pivot equally at all points of their length. The holes, if of brass or gold, must have been hammered sufficiently hard, so that the pores of the metal are closed to prevent too rapid wear. It is well if the oil sinks are of a size that will accommodate a sufficient quantity of oil, which, if too little, would soon dry out or become thickened with the worn off particles of the metal. The under-turnings of the pinion leaves are conical, but in such a way that the thicker part be nearest to the pivot, because by this disposition the oil is retained at the pivot by attraction, and does not seek to spread into the pinion leaves, as is often the case, especially with flat watches, in which this provision is frequently slighted.