Robert Stirling's Models of the Air Engine


A new book from James Rizzo is to be celebrated, and James certainly does not disappoint with this book. In it he describes in detail the two earliest surviving hot air engines, and how to build working replicas, or reduced sized models of them. 
The two engines concerned are those which Robert Stirling presented to the University of Edinburgh, and slightly later, to the University of Glasgow, to demonstrate his 'Air Engine'. The exact dates these were built is not known, but were certainly before 1825. The Edinburgh model is the more original, as the Glasgow model was discovered in an old store by Prof. William Thomson, later Lord Kelvin, in 1847. He dismantled it to see how it worked, and restored it to working order, along the way establishing the Absolute Scale of Temperature, the term “energy” and invented the name of a new science - Thermodynamics.
Both models are now very fragile, but James was granted unprecedented access to measure and inspect them by both Universities. From the resulting drawings James made half-size models of both engines, but whilst the building instructions here refer to these models, the drawings are dimensioned full size, with metric and decimal inch measurements for accurate conversion. Hardwoods were used considerably in the original engines, but other than possibly for the flywheel (12 inch diameter in the original), no castings are required. Whilst they may look similar, there are considerable differences between the two prototypes, so that making replicas or models of both is far from  an exercise in repetition.
James’ book is an important historic record of two unique survivors from the very early days of mechanisation, and a tremendous ‘projects’ book, providing the model engineer with full drawings and building instructions to build replicas, or models of both these fascinating engines.
100 page, high quality paperback, full of drawings and photographs of all parts of the engines. Paperback. Camden

See Also: Stirling BUNDLE!

Ben Geutskens of the Netherlands has built superb models of both engines:-

The Edinburgh Engine


The Glasgow Engine