The Henry System is a descending system created by Reginald Buchanan Henry for a genealogy of the families of the presidents of the United States that he wrote in 1935. It can be organized either by generation or not. The system begins with 1. The oldest child becomes 11, the next child is 12, and so on. The oldest child of 11 is 111, the next 112, and so on. The system allows one to derive an ancestor's relationship based on their number. For example, 621 is the first child of 62, who is the second child of 6, who is the sixth child of his parents.
In the Henry System, when there are more than nine children, X is used for the 10th child, A is used for the 11th child, B is used for the 12th child, and so on. In the Modified Henry System, when there are more than nine children, numbers greater than nine are placed in parentheses.
The general description of the Henry System at the top of the page, and the sample generic chart on the left above is adapted from Wikipedia: Genealogical Numbering Systems. The sample Higdon chart on the right is adapted from the genealogical register report starting on page 263 of Descendants of John Higdon and Millicent 1657-1998, by Gena Lee Theiss.
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