Hedley's Locomotive "Puffing Billy", 1813.
(This locomotive is now in the South Kensington Museum) This engine was constructed at Wylam, by Wm. Hedley, Mechanical Engineer for Mr. Christopher Blackett, the proprietor of the Wylam Colliery near New Castle on Tyne and was set to work in 1813. This engine had a wrought iron boiler with a return flue, the chimney being placed at the same end as the fire door. Two vertical cylinders were employed; the pistons and rods being connected to beams centred at each end, an arrangement known as the "grasshopper". There were four wheels of equal diameter to which the motion of the pistons was communicated by toothed gearing.
Hedley conducted careful experiments to establish the effectiveness of the adhesion of the driving wheels relative to the loads that could be pulled - see A History Of The Growth Of The Steam-Engine by Robert H. Thurston.
Rev. November 2009