There is a LDS online IGI extracted christening record for a Robert Corkill, the son of a Robert Corkill and Catherine Quayle, who was christened on 30 June 1844 in Maughold Parish, IOM.
The 1900 Henry Co, Illinois census record for Robert C. and Jane Corkill, lists the birth date for Robert Corkill as June 1844, so this may be the right family for him in the 1861 IOM census