Happy Birthday James Watt (1736) – Valve Inventor & Steam Engine Improver

James Watt, Scottish engineer
James Watt, Scottish engineer

James Watt was born , January 19th, in 1736 at Greenock, Scotland. He was a mechanical engineer and inventor who’s improvements to the steam engine were a catalyst to the industrial revolution. We have Watts to thank for the steam condenser, horsepower, early control valves and the SI unit of power the watt.

After building navigational instruments as a teenager James devoted his time and energy to improving the efficiency of steam engines. Thomas Savey and Thomas Newcomen had invented mechanical pumps a half century earlier. James Watt went to work on improving the steam engine with an understanding of its existing defects. Watt discovered the main reason engines consumed such vast quantities of steam since they were cooled during every stroke, then reheated.

Watt needed a way to condense the steam without cooling the cylinder and eventually developed the separate condenser.

Watt soon saw that in order to reduce the losses in the working of the steam in the steam cylinder, it would be necessary to find a way to keep the cylinder always as hot as the steam that entered it. A light bulb would have gone on above his head, although it wasn’t invented until the next century. He became obsessed with his work.

Boulton Watt Engine
Boulton Watt Engine

“I can think of nothing but this engine”

Watt was 29 in 1765 when he discovered his idea would work and he spent the next 11 years bringing it to market. He borrowed heavily, enlisted investors and worked surveying to pay the bills. Eventually he partnered with Mathew Boulton. Boulton recognized the potential applications for steam engines were far beyond pumping water.

Boulton, an industrialist and visionary, saw the value to have all craftsmen work in a common building — a “manufactory” (later shortened to “factory”). Before the factory craftsmen all maintained their own shops. The sweat shop was invented years later.

Boulton was certain that he could sell the engine and he supplied much needed capital. Watts hated selling, and he was up to his eyeballs in debt, so began an outstanding symbiotic partnership and eventually more inventions.


The Sun and Planet Gear System

Sun and Planet Gears (Thanks Wikipedia)

At age 45, Watt developed his next great invention — a method to convert reciprocating motion of the piston to rotating motion. The invention was the sun and planet gear system, better than a crankshaft (already patented). The sun and planet gear system permitted the rotative wheel to turn more than once per stroke of the piston. Since the piston moved slowly, this was huge.

Early Steam Control Valves

An engine patented in 1782 by Boulton and Watt had another major improvement — the steam cylinder used valves above and below the piston to connect independently to the boiler or the condenser; the piston performed work on both the upward and downward stroke. This evened out the stroking of the piston, performing equal work on each movement.

Did you know Flotech’s Southern Valve division sells and repairs control valves ?

Other major contributions developed by Watt include the steam throttling valve and the mechanism to connect the throttle to the engine governor. Used together, these devices regulated steam flow into the piston and kept a constant engine speed.

Horsepower Invented

In 1782 a British sawmill ordered an engine that was to replace 12 horses. Watt used data from a sawmill to determine that a horse could lift 33,000 pounds the distance of one foot in one minute and thus developed the units of hp to sell his engines. Watt calculated how much each company saved by using his engines rather than a team of horses. Buyers had to pay him one third of this figure every year, for the next twenty-five years. Customers hated this scheme.

By 1800, 84 British cotton mills used Boulton and Watt engines.

The watt (named after James Watt) is a derived unit of power in the International System of Units (SI). The unit, defined as one joule per second, measures the rate of energy conversion.

A Petawatt of thanks (The petawatt is equal to one quadrillion (1015) watts)  to Jimmy, my favorite Scotish inventor!