Jeff was purchased as a boy in 1718 by Deacon Thomas Wells. He remained enslaved by three or four generations of the Wells family. Please refer to the "Research Articles & Highlights" entry entitled "A Negro Man Jeff" for additional information.
"Deacon Thomas Wells owned one [an enslaved person] by the name of Jeff, who came down as an heir-loom to several successive generations." In his 1737 will, he stated "I give & bequeath unto my Dearly beloved Wife Lydia Wells all my Household stuff of every sort & kind, [and] my Negro man Jeff." - Bourne, p.408
"This 'negro man' [Jeff] was bought of Nathan Hale October 21, 1718, for £55. The original deed or bill of sale of that date, from Nathan Hale to Thomas Wells, of a 'negro boy named Jeffy,' for £55, was in the possession of Abigail Wells, daughter of Judge Wells, at the time of her death a few years ago." [Note that this was written in 1874.] - Charles K. Wells (p. 16)
Note: It is not known where Nathan Hale resided or where this transaction took place. This Nathan Hale is clearly not the famous patriot Nathan Hale who lived from 1755-1776, but may have been an ancestor of his.
Lydia died in 1746 and Jeff was passed down to Deacon Nathaniel Wells, the son of Thomas and Lydia. Nathaniel died in 1776 and left "my Negro servant" [apparently Jeff] to his wife Dorothy. She died [also in 1776?] and apparently left Jeff to her son Nathaniel a/k/a Judge Nathaniel Wells, the son of Nathaniel and Dorothy.
Bibliography:
The History of Wells and Kennebunk from the Earliest Settlement to the Year 1820 - by Edward Bourne (1875)
Genealogy of the Wells Family of Wells, Maine - Charles K. Wells (1874)