In genealogies, Thomson genealogy is the lineage that made Scottish-Irish brothers physicist William Thomson and engineer James Thomson, two the main early curators of thermodynamics, both sons of mathematician James Thomson, Sr., along with three other James Thomson's prior to him.

Thomson lineage
The Thomson clan is of Scottish origin. In 1641, it is said that three brothers James Thomson, John Thomson, and Robert Thomson, migrated from the Lowlands of Scotland, during the troubled times of the civil war. John Thomson settled in Count Down at Ballymaglave (or Ballymaglymph), and for nearly two-hundred-years his descendents continued to occupy a farm called Annaghmore, near Spa Well, Ballynahinch.

An anon son of John Thomson hand a son named James Thomson (c.1691-).

On his house, on a quoin of a building now used as a barn, this James Thomson, grandson of John Thomson, cut his name, with the date 1707 (which fixes his age to about sixteen).

This James Thomson had three sons: John Thomson, Robin Thomson, and James Thomson (c.1738-). The first two sons, John and Robin, both migrated to Buffalo Valley, New York in about 1755.

The latter son, James Thomson (c.1738), stated in Scotland, and in 1768 married Agnes Nesbitt, who bore him three sons: Robert Thomson, John Thomson, and James Thomson (mathematician). At this date the Thomson’s owned about one-quarter of the township of Ballymaglave. [1]

Overview
The following is the framework of the Thomson genealogy:

Thomson family




James Thomson (c.1616-)John Thomson (c.1619-)Robert Thomson (c.1622-)

|


Anon Thomson (c.1654-)


|


James Thomson (c.1691-)


|

John Thomson (c.1730-)James Thomson (c.1738-)
(farmer)		Robin Thomson (c.1732-)

|

Robert Thomson (1773-)James Thomson (mathematician)
James Thomson (1786-1849) (mathematician)		John Thomson (c.1780-)

|----------------------------------------|

James Thomson (s)
James Thomson (1822-1892)
(engineer)		William Thomson (1876)
William Thomson (1824-1907)
(physicist)

It is said James Thomson (farmer) gave his children what little education they could receive. [2]

References
1. Thompson, Silvanus P. (1910). The Life of William Thomson, Baron Kelvin of Largs, Volume 1 (James Thomson and Agnes Nesbitt, pg. 1-2). MacMillian.
2. James Thomson (mathematician) – MacTutor Biography, University of St. Andrews.

TDics icon ns