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James Watt · Separate condenser

Can heat be turned into force?

Engineering· 1765· Glasgow · James Watt · Separate condenser· Measure

1min readUpdated 2026-09-29

That time, that place

Eighteenth-century British mines were fighting water. The deeper the shaft, the more it flooded, and unpumped water meant no coal.

Newcomen's engine already existed, but it devoured coal. It was only practical sitting next to a coal pit.

Why this question

Repairing a model, Watt located the waste. The engine filled a cylinder with steam, then poured cold water into that same cylinder to condense it and make a vacuum.

Which cools the cylinder. On the next stroke most of the incoming steam goes into reheating the cold walls — like chilling a pan and reheating it every single time.

What was found

The fix was to condense somewhere else. Keep the cylinder hot and draw the steam off into a separate cold vessel.

Fuel use fell to about a quarter. And then the engine could leave the coal pit. Factories could be built where there was no coal and no falling water.

This is the point at which the Industrial Revolution left the riverbank.

The old idea

Power meant water wheels, wind, and an inefficient engine tied to the pit

The evidence

Direct comparison of coal burned for the same work — about a quarter

What followed

Power was freed from place, and factories could stand anywhere

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