Birth date is actually christening date.
Scotland Births and Baptisms Name Catharine Jamison Gender Female Christening Date 15 Aug 1821 Christening Place , KILMORE AND KILBRIDE, ARGYLL, SCOTLAND Father's Name Alexander Jamison Mother's Name Elizabeth Mckenzie CITING THIS RECORD
"Scotland Births and Baptisms, 1564-1950," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:XB29-Z4Y : accessed 21 December 2015), Catharine Jamison, 15 Aug 1821; citing , KILMORE AND KILBRIDE, ARGYLL, SCOTLAND, reference ; FHL microfilm 1,041,072.
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