Here is Donald’s own account of the event

written by him in 1912.

"On the granite stone bridge that crosses the River Dee at Potarch there were, and still are, two large stones weighing about 8cwt the pair, placed in a recess. In the early 1830's massive iron rings were placed in them, to which ropes were fixed so that scaffolds could be attached for pointing the bridge. Now, one of these stones was somewhat heavier than the other. Very few strong men of that day could lift the heavy one with both hands, but my father could raise one in each hand with apparent ease, and could throw the heavier stone of the two on to the top of a parapet wall of the bridge.

Those stones are still on the bridge and I myself lifted one in each hand on many occasions and one market day, I carried them across the bridge and back, some four to five yards."