In the crypt of the National Museum may be seen a historic stone which formed part of the old Bridge of Athlone, taken down in the year 1844. On this stone is sculptured the figure of a clergyman - one Peter Lewys, "by the good energy and diligence of whom this bridge was built in 1567". A rat is also chiselled biting the thumb of the clergyman's right hand, which holds what looks like a pistol.
An old tradition about this rodent was current among the inhabitants of Athlone when the old bridge stood. It was told that the rat followed and haunted Lewys by day and night; where he travelled, it travelled; and where he slept, it slept, continuing its persecution to the end of his days. One day, as the clergyman descended from the pulpit, the rat made its appearance, and Lewys levelled his pistol at it; but the animal leaped on the pistol, and, biting the clergyman's thumb, caused lockjaw, which terminated fatally.
The Irish Times, December 30th, 1930.