The physics of an 18th-century fire engine

Enlarge / An 18th-century fire engine designed and built by Richard Newsham, purchased in 1728 for St Giles Church, Great Wishford, UK. (credit: Trish Steel/CC BY-SA 2.0)

When Don Lemon, a physicist at Bethel College in Kansas, encountered an 18th-century fire engine designed by English Inventor Richard Newsham on display at the Hall of Flame museum in Phoenix, he was intrigued by its pump mechanism. That curiosity inspired him to team up with fellow physicist Trevor Lipscombe of Catholic University of America in Washington, DC, to examine the underlying fluid mechanics and come up with a simple analytical model. Their analysis, described in a new paper published in the American Journal of Physics, yielded insight into Newsham's innovative design, which incorporated a device known as a "windkessel."

A quick Google search on the "windkessel effect" yields an entry on a physiological term to describe heart-aorta blood delivery, dating back to the man who coined it in 1899: German physiologist Otto Frank. "Windkessel" is German for "wind chamber," but the human circulatory system doesn't have a literal wind chamber, so Frank's use was clearly metaphorical. However, there are earlier English uses of the wind chamber terminology that refer to an airtight chamber attached to a piston-driven water pump to smooth the outflow of water in fire engines like those designed by Newsham, per Lemon and Newsham.

Rudimentary firefighting devices have been around since at least 2 BCE, when Ctesibius of Alexandria invented the first fire pump; it was re-invented in 16th-century Europe. Following the 1666 fire that destroyed much of London, there was a pressing need for more efficient firefighting strategies. This eventually led to the invention of so-called "sucking worm engines": leather hoses attached to manually operated pumps. John Lofting is usually credited with inventing, patenting, and marketing these devices, which pulled water from a reservoir while the hose ("worm") enabled users to pump that water in a supposedly continuous stream, the better to combat fires. But nothing is known of his sucking worms after 1696.