Skip to main content

Primary sourceDocument1769 (reprinted 1855)

James Watt Patent No. 913

James Watt · 1769 (reprinted 1855)

Watt's 1769 patent for a method of reducing steam and fuel use in fire engines, describing the separate condenser that made him famous.

Watt wrote and filed this patent himself, making it the core legal record of his central invention.

Ask James Watt about this sourceView the original(opens in new tab)
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.'
James Watt, Patent No. 913, 1769 (reprint 1855).

About this source

What it is

This is the printed specification for Patent No. 913 of 1769, granted to James Watt of Glasgow. It describes his 'new invented method of lessening the consumption of steam and fuel in fire-engines.' This copy is an 1855 reprint of the original document.

Why it matters

This patent is the legal foundation of Watt's reputation as an engineer. It protected his idea of the separate condenser, which made steam engines far more efficient than earlier designs. Patents like this show how new ideas in the Industrial Revolution were owned and defended.

Look closer

  • Why would Watt want legal protection for his idea?
  • What does the formal, old-fashioned language tell you about official documents of the time?
  • What does the patent not tell you about how Watt actually built his invention?

This document 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.

More James Watt sources

Meet the AI James Watt →
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

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.Artifact

Primary source

Lap Engine

James Watt · 1788

Ready when you are

Start chatting with James Watt now.

20 messages free · No credit card · Available in 50+ languages.

Trial Humy for freeGet a quote for institutions