Following a period of training in New York offices, he found employment as Superintendent of Construction with the U. S. Supervising Architect's office in Washington, in charge of the erection of Post Office Buildings. Returning to New York during the early eighties, Mr. Thomson was associated in practice with the late Charles C. Haight for several years. In 1890 he accepted a position as Consulting Architect with the late J. L. Mott Iron Works of New York, and in that capacity planned and supervised erection of the Company’s new Plant in Trenton, N. J. After resigning that position in 1893 Mr. Thomson resumed architectural practice and with an office in Brooklyn carried on work under his own name until his death.
Elected a charter member of the Brooklyn Chapter in 1894, Mr. Thompson served as Secretary six consecutive years, and in 1896 was taken into Institute Fellowship.