In your posting, you have the wife of Henry "Harry" Cannell listed as unknown. You didn't give a birth year for Charles Seymour Cannell, so, I don't know if this is the Henry Cannell you're seeking info on, but here is an 1862 Peoria Co., Illinois marriage of a Henry Cannell and a Rachel ClarkI that I found on a search of the Illinois marriage database:
www.cyberdriveillinois.com/departments/archives/databases/marriage.html

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Groom: Cannell, Henry
Bride: Clark, Rachel A.
Date: 22/2/1862
Vol: 003
Page; 0061
Lic.No.:00006008
County: Peoria
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