'The Barnum Family' calls this person Louis Green Barnum. On 8 Oct 1828, Lois purchased from her father land in Beverly Township, Halton County (Deed #405). On 15 Oct 1828, Lois Green Kimber of Charlotteville Township filed an Upper Canada Land Petition as the daughter of a United Empire Loyalist. She and her husband moved to Seneca Township, Ontario County, New York and were listed in the 1850 Census, with William shown as a physician. After her husband died, Lois continued at Seneca Township, recorded in the 1860, 1865 and 1870 Censuses.
From 'The Loyalists in Ontario' comes the note:
"Barnum.. Nathaniel Bunnell, settled Charlotteville, his children
1. David Wheeler Barnum, got his O.C.4 Dec 1834
2. Charles D. Barnum O.C. 17 Oct 1839
3. Thomas Arnold Barnum, O.C 28 Jan 1841
4. Lois Green Barnum m. William Kimber, O.C. 3 Oct 1833
5. Henry V Barnum, O.C. 10 Mar 1834
6. James Russell Barnum, O.C. 10 Mar 1834
7. Christina Barnum m. Henry Liger, of Woodhouse, O.C. 7 Feb 1833
8. Andrew Willson Barnum of Bayham, O.C. 22 Dec 1832
9. Samantha M barnum m. James Clark of Walsingham, O.C. 6 Feb 1828
O.C. stands for "Order in Council", which means that they were now either married (if female) or over age 21, and could then claim their free land grant as a child of a Loyalist. In the case of males, it gives you a good idea of when they were born. All those with no location given were in Charlotteville, near their father.