In 1856 the canal engineer James Milne fitted a simple steam engine into what had been a standard Forth and Clyde canal iron-built and horse drawn scow, the "Thomas". The engine was a twin cylinder arrangement of 10 inch stroke and 6.5 inch bore with steam from a 3 foot diameter boiler at 35lb psi. Because the canals provided an unlimited supply of fresh water, Milne's engine could afford to exhaust its used steam direct to the atmosphere, the sound of which gave rise to the name "puffer". The Thomas was capable of carrying around 80 tons of cargo at a speed of about 4 knots
The "puffer" had been born. Little did Mr Milne realise what he had started !
further infomation is sought on this vessel