Smeaton's improvments on Newcomen steam engines

Mr. Smeaton's improvements on Newcomen's engine consisted only in proportioning its parts, but without altering any thing in its principle : it was still Newcomen's, though perfected [1].
The renowned engineer Mr. John Smeaton conducted research on the Newcomen steam engine around the year 1772, just as he had previously done with regard to water and wind mills. While not adding anything to Newcomen's invention, he did establish proportions for engines of all sizes and their performance, allowing him to select the ideal dimensions for a given requirement. Although not an in inventor his systematic research is the typical approach of an engineer. He created many of these very large engines after experimentally determining the right proportions. He constructed his engines with steam cylinders that had longer strokes than was used before and gave them such lengths that he could substantially enhance the piston's speed by applying a bigger excess of steam pressure. In 1774, at Long Benton, not far from Newcastle upon Tyne, the first of his new design of engines was built. [2]. The performance of the engines built by Smeaton was far superior to the common type of engines that were typically made before his time [3].
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[1] John Farey, A treatise on the steam engine : historical, practical, and descriptive, London 1827, page 307 available INTERNET ARCHIVE
[2] Robert H. Thurston, A History of the Growth of the Steam Engine, New York, 1878 available at "Scientific Library"
[3] John Farey, page 134.