From "Pittsburgh Gazette Abstracts 1797-1803, Vol. II" (Compiled by Clara E. Durer, no date), page 34:
$50 Reward.Henry Wise offers the above reward to any person or persons who will apprehend and safely lodge in the goal of the state, a certain David McKessock, who was sentenced to undergo an imprisonment in the gaol and penitentiary house in Philadelphia, and who effected his escape from the subscriber when conducting him to the said gaol, agreeably to his sentence on conviction.The said McKessock is about 2 years from Ireland, out of county of Derry, and by trade, a weaver.He is about 5' 7" high, of a florid complexion, and fair hair, which he commonly wears tied or queued; he made his escape at the peach orchard, 4 miles from Fort Littleton, and had on a high crowned black hat, a dark brown coat, red jacket, olive coloured velvet breeches and blue stockings, and had a small iron chain fastened to his right leg.Greensburgh, July 26.
From the 05 August 1797 newspaper.
Not my family--but of real interest!Greensburg is in Westmoreland County, in Western Pennsylvania.