Autograph letter from William Brunton to his brother John, written whilst he was working at the Butterley Iron Works near Derby giving a description of his Steam Horse, patent no.3700/1813, dated April 28th 1813. The letter includes diagrams and an explanation of the workings of the 'legs' and 'feet' that propelled the engine. Also included are examples of how the materials and design could be change to suit different surfaces and how the mechanism could be attached to boats for use on canals. The letter is addressed to Job Rider, a watch maker and engineer of Belfast, for whom John Brunton was working and was received on 11th May 1813