Road steamer 'Derwent', c 1868..
© Science Museum / Science & Society Picture Library
Albumen photograph showing Thomson's road steamer 'Derwent' in operation at Leith, Edinburgh, Scotland. Thomson built his first road steamer in November 1867 and then ran that as a prototype for a while. Subsequently he started building others from the middle of 1868 through to 1870 when production was taken over by Tennants of Leith.