science · 13 July 1781 · 243 years ago
In 1781, a British patent was taken out for the first compound steam engine by Jonathan Carter Hornblower (No. 1298). His invention was to use two cylinders of unequal size attached to the same beam. Steam acts first in a small high-pressure cylinder, leaving at a lower pressure, but still sufficient to expand further in a larger cylinder. Although he claimed greater efficiency, this was not realised at the low steam pressures of the day. Boulton and Watt claimed infringement on their earlier patent since this engine still used a separate condenser, so Hornblower had to abandon that design at the time. His compound steam engine principle was later revived in 1804 by Arthur Woolf using higher steam pressure with better results.
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