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Primary sourceArtifact1785

Whitbread Engine

James Watt · 1785

The oldest surviving rotative steam engine, designed by James Watt and installed in 1785 at Whitbread's London brewery.

Designed by Watt, this engine shows his technology being applied to industry beyond mining, at a London brewery.

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A large Boulton and Watt steam engine displayed in a museum hall. A tall wooden cylinder with iron bands stands on a grey pedestal, with black iron machinery, pipes and a flywheel behind it. A metal staircase and platforms rise on the left beside an old stone wall.
Boulton & Watt steam engine, designed by James Watt, installed 1785 at Whitbread's brewery, London. Powerhouse Museum, Sydney.

About this source

What it is

This rotative beam engine was designed by James Watt of Boulton and Watt and installed in 1785 at Samuel Whitbread's brewery in London. It is the oldest surviving rotative steam engine in the world, and after decommissioning in 1887 it was shipped to the Powerhouse Museum in Sydney, where it has been restored to working order.

Why it matters

This engine shows Watt's technology moving beyond pumping water out of mines into driving machinery in ordinary industry, here crushing malt and pumping beer at Whitbread's brewery. Its visit by King George III and Queen Charlotte in 1787 shows how notable this new technology was considered at the time. The engine embodies several of Watt's key innovations, including the separate condenser, parallel motion, centrifugal governor and sun and planet gear.

Look closer

  • Why would a brewery want to replace a horse-powered wheel with a steam engine?
  • What does a royal visit to see the engine tell you about its importance at the time?
  • What has changed about this engine since 1785, and what does that tell you about how museums preserve old machines?

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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Printed first page of Watt's Specification, patent No. 913 dated A.D. 1769, headed Steam Engines, &c., with a royal coat of arms above. The text begins 'To all to whom these presents shall come, I, James Watt, of Glasgow, in Scotland, Merchant, send greeting.'Document

Primary source

James Watt Patent No. 913

James Watt · 1769 (reprinted 1855)

Dark metal cylindrical object standing upright on a wood-grain surface, viewed from above. It has a short pipe projecting from its left side, and a hand-painted marking reading roughly '1744-786' runs down its front.Artifact

Primary source

Watt's First Condenser

James Watt · c. 1765

A dark metal and wood model steam engine in a glass case on a white pedestal. It has a tall cylinder with a funnel-shaped top, a rocking beam across the top frame, and a cylinder with a piston and a wooden base frame.Artifact

Primary source

Model Newcomen Engine Repaired by James Watt

Unknown maker (repaired by James Watt) · c. 1760

Interior of a cluttered 18th-century style workshop with a wooden workbench, a large iron lathe-like machine, shelves of white ceramic jars and stoneware, plaster busts and casts, and hanging chains and a beam overhead. A window is at the left.Artifact

Primary source

James Watt's Workshop

Interior of a museum showing the Smethwick Engine: a large dark cylinder with a steam pipe and valve rises beside a steel walkway. Above, wooden beams and a large iron beam structure stand. In the background, a red-spoked flywheel engine sits on a green base.Artifact

Primary source

Smethwick Engine

James Watt · 1779

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