James Watt (1736-1819)
Category: Straight Line Mechanisms
Item Number: S24, S25
Description: Lemniscoidal Linkage of the First Kind by Watt ; Lemniscoidal Linkage of Watt (II. and III. Kind)
Image: Portrait of James Watt by Carl Frederik von Breda (1792), oil on canvas, original is on display at the National Portrait Gallery, UK; Cornell University has a copy of this portrait.
James Watt was born 1736 in Greenock, Scotland. Watt's father, the treasurer and magistrate of Greenock, ran a successful ship- and house-building business. A delicate child, Watt first was taught at home by his mother; later, in grammar school, he learned Latin, Greek, and mathematics. The source for an important part of his education was his father's workshops, where, with his own tools, bench, and forge, he made models (e.g., of cranes and barrel organs) and grew familiar with ships' instruments.
Watt was originally trained as an instrument maker in London, England, and when he returned to Scotland, he opened a shop in 1757 at the Glasgow university and made mathematical instruments (e.g., quadrants, compasses, scales). He met many scientists and became a friend of Joseph Black, who developed the concept of latent heat. In 1764 he married his cousin Margaret Miller, who, before she died nine years later, bore him six children.. Watt was asked to repair the University's model of Newcomen steam engine. During the repair however, Watt found many areas of the engine's design that he believed could be improved. Over the next several years, Watt improved the design of the Newcomen engine by adding a separate condensing chamber. Watt got his first patent on steam engine design in 1769. After Watt's patent was extended by an act of Parliament, he and Boulton in 1775 began a partnership that lasted 25 years. Boulton's financial support made possible rapid progress with the engine. In 1776 two engines were installed, one for pumping water in a Staffordshire colliery, the other for blowing air into the furnaces of John Wilkinson, the famous ironmaster. That year Watt married again--his second wife, Ann MacGregor, bore him two more children.
During the next five years, until 1781, Watt spent long periods in Cornwall, where he installed and supervised numerous pumping engines for the copper and tin mines, the managers of which wanted to reduce fuel costs. Watt, who was no businessman, was obliged to endure keen bargaining in order to obtain adequate royalties on the new engines. By 1780 he was doing well financially, though Boulton still had problems raising capital. In the following year Boulton, foreseeing a new market in the corn, malt, and cotton mills, urged Watt to invent a rotary motion for the steam engine, to replace the reciprocating action of the original. He did this in 1781 with his so-called sun-and-planet gear, by means of which a shaft produced two revolutions for each cycle of the engine. In 1782, at the height of his inventive powers, he patented the double-acting engine, in which the piston pushed as well as pulled. The engine required a new method of rigidly connecting the piston to the beam. He solved this problem in 1784 with his invention of the parallel motion--an arrangement of connected rods that guided the piston rod in a perpendicular motion--which he described as "one of the most ingenious, simple pieces of mechanism I have contrived." Four years later his application of the centrifugal governor for automatic control of the speed of the engine, at Boulton's suggestion, and in 1790 his invention of a pressure gauge, virtually completed the Watt engine. Improved steam engines made it possible for smaller industries, such as cotton spinning, to become large factory industries, thus advancing the Industrial Revolution.
Even steam engines are no more used industrially, we still remember James Watt for his legacy in engineering history. There is the energy measurement unit called a "watt", a unit of energy equal to one joule per second - every time you are changing a little bulb, you are checking that! James Watt himself introduced a unit called the horsepower to compare the power output of steam engines, his version of the unit being equivalent to 550 foot-pounds per second (about 745.7 watts).
He was elected fellow of the Royal Society of London in 1785.
James Watt died at Hatfield in 1819 at the age of 83 and was buried in Handsworth Church. A book about him titled "James Watt". written by Andrew Carnegie. was published in 1905.
Sources for Further Information on Watt:
1. Carnegie Andrew, James Watt, New York: Doubleday, Page & Company,May, 1905.
2. 1994-2001 Encyclopędia Britannica, Inc.
3. http://www.tartans.com/articles/famscots/jameswatt.html
4. http://www.spartacus.schoolnet.co.uk/SCwatt.htm
5. Roy Porter and Marilyn Ogilvie (eds.). The Biographical Dictionary of Scientists. V. 2 (Lebedev to Zworykin). New York: Oxford University Press, 2000.
