Sonia,I was thinking about your search the other day and the idea came to me that your Thomas Thompson's original name might also be another Norwegian name, Tønnes Tønneson.Syllabification is similar and when pronounced might also be understood in the English ear as Thomas, etc.
So I went back to the 1865 census looking for children with these characteristics:
first name containing (fornavn): tønis, tønne, tønnes, tønni last name containing (etternavn): tønes, tønnes, tønnesen, tønness, tønnessen and birth year of 1854+/- 2 years -(fodeaar): 1852, 1853, 1854, 1855, 1856
These are the numerical results by county (fylke) and then parish within the fylke:
Fylke Vest Agder: Parish: 1 each Christiansand, Mandal, Farsun, Oddernæs, Søgne, Lyngdal, 2 in Flekkefjord, 2 in Næs og Hitterø, 2 in Bakke, 3 in Farsund og Vanse,15
Fylke Rogaland: Parish: 1 each in Sogndal, Egersund og Ougne, Haa, Ly2 each inLunde, Helleland8
Of this total of 23 I found there are only 2 whose father's occupation is rendered as carpenter or something similar snikker, snedker, tømre:
Not found in the Farsund utflyttedes 1872-1879 Not found in 1900 censys Tønnes search:
Sometimes in death records, church funeral records and on headstones a person's age is written or carved as __ years, __ months, __ days.Even though this is not an exact repetition of the date of birth, genealogical programs do have capabilities of figuring a birth date from an exact date of death and this numerical rendering of age.