NEVER shall it be said that English Mechanics neglected its "minority" readers! A few regular followers of these notes, both old and new hands at locomotive building, point out that those who favour the modern locomotive with its big boiler, multi-coupled wheels, and three or four cylinders, have had their requirements well catered for during the past few years; why not give a turn to lovers of old-tune engines, and offer a brief description of some celebrated locomotive of a bygone era ? With our worthy Editor's permission I am only too anxious to oblige; so, as a "direct opposite" to the "Green Arrow," here are some notes on a small copy of what is probably the most famous type of locomotive that made history over the very same tracks where the "Green Arrow" now runs - to wit, the Stirling eight-foot single-wheeler, of the old Great Northern Railway.
Patrick Stirling was a practical man with sound ideas; eg., he believed in a boiler having ample firebox volume - a totally different thing from an outsize in grates - and carrying a fairly high steam pressure. He was very adaptable; although favouring inside-cylinder six-wheelers, he placed the cylinders, of the eight-footer outside, to obviate the necessity of an extremely high pitched boiler in order to clear a cranked axle, and provided a bogie both to carry the weight and to allow the cylinders to be placed horizontally. The engines were remarkably successful, and were also great favourites among small loco. enthusiasts, hundreds of "little sisters" being built; but unfortunately, owing to the ideas prevailing about valve gears and cylinder sizes in those days, the small editions were dismal failures. They would not steam, and the small boiler was blamed. But those of us who broke away from accepted "model" tradition, and copied the valve gears and settings of the big machines, found out how to use steam instead of wasting it and so achieved success. The 2½-in. gauge Stirling single-wheeler has a boiler only of 2¼-in. diameter, which fits between the driving wheels; yet the engine will haul a live passenger continuously. As wheel-turning, cylinder boring, and other machining and fitting details are exactly the same as described in detail for previous engines in this series, I will not repeat them, but just run through the principal points, which will keep the instructions as brief as possible, yet enable anyone who is interested to build the engine.
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