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Primary sourceArtifact1788

Lap Engine

James Watt · 1788

A 1788 rotative beam engine by Boulton and Watt, used to power polishing machines at Matthew Boulton's factory, showing Watt's engine driving industry.

Designed by Watt, this engine shows his inventions combined to power factory machinery for his business partner Matthew Boulton.

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A large historic wooden beam engine with a massive toothed gear wheel and iron fittings, displayed in a museum atrium. Visitors walk on upper galleries behind glass railings, and a brick wall stands at right.
Lap Engine, 1788, designed by James Watt, built by Boulton and Watt. Science Museum, London.

About this source

What it is

The Lap Engine is a beam engine designed by James Watt and built by Boulton and Watt in 1788. It is now preserved at the Science Museum in London. It was used at Matthew Boulton's Soho Manufactory to drive a line of 43 polishing machines making buttons and buckles.

Why it matters

This engine brought together several of Watt's major innovations in one machine, including parallel motion, sun-and-planet gearing, and the first use of a centrifugal governor on a steam engine. The sun-and-planet gear was actually invented by Watt's employee, William Murdoch, showing how Watt's success depended on a team of skilled engineers, including his business partner Matthew Boulton.

Look closer

  • Why did Watt need a way to turn the piston's back-and-forth motion into rotary motion?
  • Why might Watt have avoided using the crank, which was already patented by someone else?
  • What does this engine show about teamwork behind famous inventions?

This artifact is part of the curated material that grounds the AI version of James Watt on Humy.ai — when students ask about related events, the AI can quote it and cite it.

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