In this letter from Matthew Boulton to Erasmus Darwin, Boulton describes the differences between the B&W steam engines and the earlier Newcomens engines. Instead of boasting about the success of the B&W engine, he prefaces his description by stating that the letter is simply a factual list and can be interpreted however Darwin pleases. Boulton includes 6 principle differences between the two engines:
- The acting power is steam on the piston and not on the atmosphere as the common engine
- The steam is condensed in a separate vessel and not in the cylinder
- The cylinder is kept as hot as the steam, and not alternatively heated and cooled
- The air is extracted by an air pump at each stroke, and not blown out by a snifting valve
- The packing of the piston is preserved air and steam tight and not by water
- The vacuum is made above and below the piston, thus doubling its power
Boulton also provides calculations for the power of the B&W engine in comparison to horses. His conclusion is that the B&W engine has the same power as 1000 horses and is able to work constantly, as long as it is fueled, whereas a horse must rest. Boulton also explains the wide range of uses for the engine, and concludes that it is applicable to anything that utilizes rotational or reciprocating motion.
In order to better understand steam engines, this link explains in great detail how steam engines work, especially in trains. The detailed step-by-step description is much easier to understand than Boulton’s letter and simplifies the process enough to understand without an extensive background in engineering. The article also provides a detailed history of the development of steam engines. Additionally, this link details the process for developing the B&W steam engine that Boulton discusses in his letter.
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