Born November 1st, 1853, at Cannington, Ontario, son of Lt.-Col. John Hall Thompson and Margaret Cowan, daughter of Matthew Cowan, captain in an Irish Cavalry Regiment.
- Educated in Public and Grammar schools and McGill University.
- Articled to Hugh D. Lumsden in 1872.
- Obtained his PLS, Ontario commission in 1875.
- Got B.A.Sc. and M.A.Sc and C.E. with first rank honours in natural science (McGill) 1877 and M.A. Sc. in 1882.
- Commissioned DLS and DTS in 1877.
- Remained in private practice in Ontario and Victoria counties, working from Cannington till 1880.
- Surveyed Gillmore Township in 1878.
While serving under articles was on surveys for Northern Railway from Washago to Bracebridge, the Credit Valley Railway from Toronto westward and North Grey Railway from Collingwood to Owen Sound.
During 1879, along with Arthur Maddock, an articled pupil, and Jeff Avery, an expert canoe man, he made a trip to Hudson Bay going via the Muskoka, Petewawa, Amble du Fond and Mattawa rivers to the Ottawa, then up that river and a tributary to the height of land, crossed over into the Abitibi and Moose to Hudson Bay. Returned by Moose and Missinabi Rivers and crossed the height of land into the Michipicoten River down to Lake Superior and steamer to Owen Sound. His object in making the trip was to gain some knowledge of the minerals in the country traversed. He found lignite at the junction of some of the creeks and gypsum on the lower Abitibi and Moose rivers, and indications of silver on the Michipicoton. He made a rough map of the country traversed, approximately 1,000 miles, and sent a copy to the Crown Lands Department at Toronto, and had an account of his explorations published in The Globe in December of that year.
In 1880 he was instructed by Lindsay Russell, then Surveyor General of Canada, to go West and work on block outline surveys, then inaugurated. He continued at that work, working west and northerly into the Peace River country and to the British Columbia boundary, till end of 1883. In 1884, he located at Qu'Appelle and spent that year exploring for a railway from Wood Mountain to Touchwood Hills, and located the part from Qu'Appelle to the Fort, but nothing further was done and the charter was allowed to lapse.
From 1886 to 1895, he was engaged in making road surveys in the Indian Head and Qu'Appelle region, and subdivided a number of townships near Good Spirit and Buffalo Lakes. In 1896, on organization of the Government of Northwest Territories, he was appointed District Surveyor and Engineer of Public Works for Qu'Appelle district, adjacent to and west of Manitoba, and continued to hold that office till 1922. During that time he resurveyed a number of townships in the Touchwood Hills vicinity, and a number of timber berths on the Saskatchewan and Carrot rivers. During this period, he lived successively at Qu'Appelle Station, Grenfell, Regina and Preeceville.
In 1922, he went to Cranberry Portage, Manitoba, and from there carried on a private practice for the rest of his life. He obtained his SLS commission in 1907, and his MLS commission in 1930. He was appointed police magistrate for the mineral belt of Manitoba in 1925. He was president of the Cranberry Portage Board of Trade 1928 to 1934.
In July, 1938, he went to Cold Lake, Manitoba, to survey some mineral claims. It was necessary to make a triangulation across Rabbit Lake to tie two groups of claims together and for definite location of his work, he had established his base on the southwestern shore of the lake, and was proceeding to his station on the other side of the lake, when he became separated from the two men who were assisting him. This seems to have been on July 8th but he was not seen again till the 18th when his body was found on the shore of Cold Lake, about fifteen miles from the place he had set out to go to. It is not known whether he died from starvation or from a heart attack brought on in his weakened condition, by attempting to raise a pole with a blueprint on it for a flag, to attract attention of searchers to the place where he was. He was over 84 years old, and said to have been the oldest practicing surveyor in Canada.
He devised a micrometer attachment for use in latitude and other observations, and invented a method of making sidehill grade locations, with a transit, which he used for many years, and described it in a paper read before the E.I.C.
He was a strong advocate of the Hudson Bay Railway and believed it would eventually be a great benefit to Western Canada. In February 1938, he wrote that he proposed going to England via that route during the next navigation season. He wrote numerous articles to the newspapers on different occasions, and wrote "A Prospector's Map of the Mineral Belt North of the Pas, Manitoba," in 1925, and was engaged in writing his experiences, to be published in book form, at the time of his demise.
Five men served with him and obtained commissions: Arthur Maddock, PLS, Ontario, John Swan, B.A.Sc., Lt.-Col. J.H. Vicars, Lt.-Col. A.C. Garner and Edgar C. Brown, all commissioned as Dominion Land Surveyors.
He came of military stock, his great grandfather and grandfather were officers in H.M. 40th Foot Guards, and saw service in America before the Revolution. His grandfather, Major Joseph Thompson, retired on pension and settled in Brock Township in 1834, one of whose sons, John Hall Thompson (W.T.T.'s father), having been well educated in England, was appointed road surveyor in his home district, the principal work being locating roads to the settlements through Indian Reserves. John Hall Thompson became interested in political and military affairs in his home district, and was Reeve of Brock Township and warden of Ontario County for many years, and after Confederation represented the north riding of Ontario County in the House of Commons from 1867 till 1873.
William T. Thompson married Mary, daughter of Rev. Alexander MacKay, M.A., of Summerstown, Ontario, on December 14th, 1887. Their children were Edith Mary, Lt. John Alexander (killed at Festubert, France, 1915), Lt. William Thomas (killed at Cambrai, France, 1918), George Francourt, Vaughan Ball and Margaret Rose. His widow, three boys and two girls survived him.
By E.T. Wilkie, and his son, George F. Thompson, Association of Ontario Land Surveyors