The following data is extracted from Genealogy and Biography of Ontario County, New York.
Cephus, grandfather of William Frederick Clark, was born in Keene, New Hampshire, and was engaged in agricultural pursuits. He was an active participant in the war of 1812, and at the close of that conflict returned to his rural occupations. He married Deborah Wilbur, a descendant of one of the eighteen original purchasers of Rhode Island. They had children : Frederick P. A., see forward; Caleb A.: Amasa F.; Alva W.; Cephus C.; Nathaniel E.; Ezra L. ; Deborah; Alfreda; Abigail; and Candice.
Source: Genealogy and Biography of Ontario County, New York