Riddle was born in Martinsburg, Virginia, on April 14, 1805 and graduated from Jefferson College in 1823, at the age of 18.

[2] Riddle's leadership following the disaster was instrumental in the university remaining in the city of Pittsburgh and continuing to hold classes in temporary rooms until a new building could be erected.

[6] Riddle's years serving as acting Principal principally involved overseeing the rebuilding of the university which included investing the university's remaining financial assets, reassembling collections of equipment and resources, and securing a site for the erection of a new building.

It was located on the corner of Ross and Diamond (now Forbes Avenue) streets, on the site of the present day City-County building.

[4] The building whose construction was overseen by Riddle housed the university until 1882, when it was sold to Allegheny County to replace its courthouse that was destroyed in a fire that year.