Andrew Thomson, civil engineer in Glasgow.
Some writers refer to him as Thompson.
1840 Thomson designed and built an innovative bridge to carry Carmunnock Road over the Polloc and Govan Railway. It is the first known bridge with wrought iron box girders, made from 3/8" iron plate. There were six 18-inch deep girders 35ft 3in long. Unlike later box girders, which were of rectangular section, these were of isoceles trapezium section, approx 3" apart at the top, 6" at the bottom. The side plates were connected to the top and bottom flange plates by angle iron. The span was 31ft 6in on the skew (30ft square). Brick arches were constructed between the girders, which explains the tapered flanks of the girders, which were inclined to suit the angle of abutting bricks. The space inside the girders was filled with concrete.
1844 Advert for sale in Glasgow of the philosophical instruments, scientific books, office furniture, etc., of the late Andrew Thomson, Esq., Civil Engineer, including 21 vols of the Encyclopedia Britannica, professional papers and the Transactions of the Royal Engineers, late editions of popular works on railways, rails, locomotive engines, bridges, civil engineering, carpenty, &c., by Pambour, Wishaw, Tredgold, Wood, Lardner, Brees, Buck, and others' theodolites, pentagraph, levels, by Abraham and others.
Sources of Information
-  'Description of the Tubular Beam Bridge on the Carmunnock Road, over the Polloc & Govan Railway' Erected by Andrew Thompson Esq., Engineer, of Glasgow. Paper read by T L Donaldson at the RIBA, 22 Jan 1849: The Civil Engineer & Architect's Journal, p.57. NB 440 page pdf
- Glasgow Herald - Monday 27 May 1844