Editing William Hedley (section)

===First locomotive===
Hedley felt that if the pairs of wheels were connected, as with [[Richard Trevithick]]'s engines, if one pair began to slip, it would be counteracted by the other. The mine owner, [[Christopher Blackett]] had just replaced the wooden [[waggonway]] with iron flanged 'L' section plate rails. Hedley first constructed a test carriage operated by manpower, to test the [[Rail adhesion|adhesion]] under various loads. He then used it as the chassis for a locomotive constructed to Trevithick's pattern with a single cylinder and a simple straight through fire tube to the boiler.  This engine was not satisfactory. Its motion was erratic, because of the single cylinder, and it produced insufficient steam.