Mellor's patent lock nut and bolt

Mellor's patent 1884. Lock Nut and bolt 5/8 in diam. (wire through nut and grooved into bolt)

In this nut-locking arrangement, patented by Mr. Mellor in 1884, two longitudinal grooves are cut through the thread of the bolt, and two inclined holes are drilled through the nut from its side to its thread; a piece of wire passed through one of the holes can be forced along the groove in the bolt, and then bent so as to retain itself in position, while also acting as a key between the nut and bolt. The holes in the nut are 90 deg. apart, and the grooves in the bolt being opposite, there are four points in each turn in which the nut can be locked.