A current entering by the trunnion -}- B flows round the two halves of the circuit, as shown by the arrows, and comes out at the trunnion - B.
Owing to the conical shape of the early muzzle-loading guns, if one trunnion were higher than the other, the " line of metal " would no longer be in the same vertical plane as the axis; in consequence of this, if a gun with, say, one wheel higher than the other were layed by this line, the axis would point off the target to the side of the lower wheel.
The bearings for receiving these trunnions are V-shaped; the V on one side is fixed, while the other is cut through and can be narrowed or made wider, thus lifting or lowering the trunnion by means of two capstan-headed screws.
The verniers are attached to arms uu bearing on an enlargement of one trunnion of the telescope, one arm pro j ecting downwards and embracing a projection on the standard t.
Watkin, C.B., introduced a hydroclinometer fixed on the trunnion.
To make the ligament, a very large number of exceedingly fine copper wires laid close together are soldered to the upper surface of the upper trunnion.