Watt, James

Watt, James (1736-1819), Scottish inventor and mechanical engineer, renowned for his improvements of the steam engine.

Watt was born on January 19, 1736, in Greenock, Scotland. He worked as a mathematical-instrument maker from the age of 19 and soon became interested in improving the steam engines, invented by the English engineers Thomas Savery and Thomas Newcomen, which were used at the time to pump water from mines.

Watt determined the properties of steam, especially the relation of its density to its temperature and pressure, and designed a separate condensing chamber for the steam engine that prevented enormous losses of steam in the cylinder and enhanced the vacuum conditions. Watt's first patent, in 1769, covered this device and other improvements on Newcomen's engine, such as steam-jacketing, oil lubrication, and insulation of the cylinder in order to maintain the high temperatures necessary for maximum efficiency.

At this time, Watt was the partner of the British inventor John Roebuck, who had financed his researches. In 1775, however, Roebuck's interest was taken over by British manufacturer Matthew Boulton, owner of the Soho Engineering Works at Birmingham, and he and Watt began the manufacture of steam engines. Watt continued his research and patented several other important inventions, including the rotary engine for driving various types of machinery; the double-action engine, in which steam is admitted alternately into both ends of the cylinder; and the steam indicator, which records the steam pressure in the engine. He retired from the firm in 1800 and thereafter devoted himself entirely to research work.

The misconception that Watt was the actual inventor of the steam engine arose from the fundamental nature of his contributions to its development. The centrifugal or flyball governor, which he invented in 1788, and which automatically regulated the speed of an engine, is of particular interest today. It embodies the feedback principle of a servomechanism, linking output to input, which is the basic concept of automation. The electrical unit, the watt, was named in his honor. Watt was also a renowned civil engineer, making several surveys of canal routes. He invented, in 1767, an attachment that adapted telescopes for use in measurement of distances. Watt died in Heathfield, England, on August 19, 1819.

Scheele, Carl Wilhelm

Scheele, Carl Wilhelm (1742-1786), Swedish chemist, noted for his discovery of a great number of elements, compounds, and chemical reactions.

Scheele was born in Stralsund, Germany, which at that time was the capital of Swedish Pomerania. He had no formal training in chemistry and studied the elements of science while apprenticed to an apothecary. In 1770 he came under the guidance of Swedish chemist Torbern Bergman. In 1775 Scheele became the proprietor of a pharmacy in Köping, Sweden, where he continued his chemical research. He is credited with the identification of the elements chlorine and barium, but Scheele believed that they were compounds, not elements. British chemist Sir Humphrey Davy recognized chlorine and barium as elements in the early 1800s. Scheele prepared oxygen from various oxides independently of and somewhat before English chemist Joseph Priestley, who is credited with the discovery of the element. He was the first to prepare many compounds, including tartaric acid, arsine, and hydrogen sulfide. He demonstrated that lactic acid was the acid component of sour milk. He also determined the properties and composition of hydrogen cyanide and those of citric, malic, oxalic, and gallic acids. In 1931 the Collected Papers of Carl Wilhelm Scheele was published.

Priestley, Joseph

Priestley, Joseph (1733-1804), British chemist, who isolated and described several gases, including oxygen, and who is considered one of the founders of modern chemistry because of his contributions to experimentation.

Priestley was born on March 13, 1733, in Fieldhead, Yorkshire, the son of a Calvinist minister. Priestley trained as a minister of the Dissenting church, which comprised various churches that had separated from the Church of England. He was educated at Daventry Academy, where he became interested in physical science. His first ministry was at Needham Market, Suffolk, in 1755, and he was minister at Nantwich from 1758 to 1761. Later he became a tutor at Warrington Academy in Lancashire, where he was noted for his development of practical courses for students planning to enter industry and commerce. He also wrote a text, Rudiments of English Grammar (1761), which differed from older, classical approaches. He was ordained in 1762.

Priestley was encouraged to conduct experiments in the new science of electricity by the American statesman and scientist Benjamin Franklin, whom he met in London in 1766. Priestley wrote The History of Electricity the following year. He also discovered that charcoal can conduct electricity. In 1767 Priestley became minister at Leeds, where he grew interested in research on gases. His innovative experimental work resulted in his election to the French Academy of Sciences in 1772, the same year in which he was employed by William Petty Fitzmaurice, 2nd earl of Shelburne, as librarian and literary companion.

During Priestley's experiments in 1774, he discovered oxygen and described its role in combustion and in respiration. An advocate of the phlogiston theory, however, Priestley called the new gas dephlogisticated air and did not completely understand the future importance of his discovery. The Swedish chemist Carl Wilhelm Scheele may have discovered oxygen before Priestley, but did not make his work known in time to be credited with its discovery. Priestley also isolated and described the properties of several other gases, including ammonia, nitrous oxide, sulfur dioxide, and carbon monoxide. During his career, Priestley remained opposed to the revolutionary theories of the French chemist Antoine Lavoisier, who gave oxygen its name and correctly described its role in combustion.

In 1780 Priestley left his position with Petty because of religious differences. He became a minister in Birmingham. By this time he had turned to Unitarian thinking, and was considered a religious radical. His book, History of the Corruptions of Christianity (1782), was officially burned in 1785. Because of his open support of the French Revolution, his house and effects were burned by a mob in 1791. He went to live in London, and in 1794 he emigrated to the United States, where he pursued his writing for the remainder of his life. Priestley died in Northumberland, Pennsylvania, on February 6, 1804. His posthumously collected Theological and Miscellaneous Works (25 volumes, 1817-1832) and Memoirs and Correspondence (2 volumes, 1831-1832) cover a wide variety of subjects in science, politics, and religion.

Franklin, Benjamin

Franklin, Benjamin (1706-1790), American printer, author, diplomat, philosopher, and scientist, whose many contributions to the cause of the American Revolution (1775-1783), and the newly formed federal government that followed, rank him among the country’s greatest statesmen.

Franklin was born on January 17, 1706, in Boston. His father, Josiah Franklin, a tallow chandler by trade, had 17 children; Benjamin was the 15th child and the 10th son. His mother, Abiah Folger, was his father’s second wife. The Franklin family was in modest circumstances, like most New Englanders of the time. After his attendance at grammar school from age eight to ten, Benjamin was taken into his father’s business. Finding the work uncongenial, however, he entered the employ of a cutler. At age 13 he was apprenticed to his brother James, who had recently returned from England with a new printing press. Benjamin learned the printing trade, devoting his spare time to the advancement of his education. His reading included Pilgrim’s Progress by the British preacher John Bunyan, Parallel Lives, the work of the Greek essayist and biographer Plutarch, Essay on Projects by the English journalist and novelist Daniel Defoe, and the Essays to Do Good by Cotton Mather, the American Congregational clergyman. When he acquired a copy of the third volume of the Spectator by the British statesmen and essayists Sir Richard Steele and Joseph Addison, he set himself the goal of mastering its prose style.

In 1721 his brother James Franklin established the New England Courant, and Benjamin, at the age of 15, was busily occupied in delivering the newspaper by day and in composing articles for it at night. These articles, published anonymously, won wide notice and acclaim for their pithy observations on the current scene. Because of its liberal bias, the New England Courant frequently incurred the displeasure of the colonial authorities. In 1722, as a consequence of an article considered particularly offensive, James Franklin was imprisoned for a month and forbidden to publish his paper, and for a while it appeared under Benjamin’s name.

CGS System

CGS System, also centimeter-gram-second system (usually written “cgs system”), a metric system based on the centimeter (c) for length, the gram (g) for mass, and the second (s) for time. It is derived from the meter-kilogram-second (or mks) system but uses certain special designations such as the dyne (for force) and the erg (for energy). It has generally been employed where small quantities are encountered, as in physics and chemistry.