James Watt

Biography

James Watt was born on 19 January, 1736 in Greenock, a seaport on the Firth of Clyde. His father was a shipwright, ship owner and contractor, while his mother, Agnes Muirhead, came from a distinguished family and was well educated. Both were Presbyterians and strong Covenanters.

Watt attended school irregularly but instead he was mostly schooled at home by his mother. He exhibited great manual dexterity and an aptitude for mathematics, although Latin and Greek left him cold, and he absorbed the legends and lore of the Scottish people.

When he was 18, his mother died and his father's health had begun to fail. Watt travelled to London to study instrument-making for a year, then returned to Scotland - to Glasgow - intent on setting up his own instrument-making business. However, because he had not served at least seven years as an apprentice, the Glasgow Guild of Hammermen (any artisans using hammers) blocked his application, despite there being no other mathematical instrument makers in Scotland.

Watt was saved from this impasse by three professors of the University of Glasgow, who offered him the opportunity to set up a small workshop within the university. It was established in 1758 and one of the professors, the physicist and chemist Joseph Black, became Watt's friend.

In 1764, Watt married his cousin Margaret Miller, with whom he had five children, two of whom lived to adulthood. She died in childbirth in 1772. In 1777 he married again, to Ann MacGregor, daughter of a Glasgow dye-maker, who survived him. She died in 1832.

Watt had a brother by the name of John. He was shipwrecked when James was 17.

Four years after opening his shop, Watt began to experiment with steam after his friend, Professor John Robison, called his attention to it. At this point Watt had still never seen an operating steam engine, but he tried constructing a model. It failed to work satisfactorily, but he continued his experiments and began to read everything about it he could. He independently discovered the importance of latent heat in understanding the engine, which, unknown to him, Black had famously discovered some years before. He learned that the University owned a model Newcomen engine, but it was in London for repairs. Watt got the university to have it returned, and he made the repairs in 1763.

It too just barely worked, and after much experimentation he showed that about 80% of the heat of the steam was consumed in heating the cylinder, because the steam in it was condensed by an injected stream of cold water. His critical insight, to cause the steam to condense in a separate chamber apart from the piston, and to maintain the temperature of the cylinder at the same temperature as the injected steam, posed a problem. How was the steam to be transferred from the cylinder to the condenser? The solution came in the course of a walk upon Glasgow Green. He suddendly realised that, as 'nature abhors a vacuum', the answer was to create a vacuum in the condensor which would suck the steam from the cylinder. By the time he had reached the golf links, he had worked out a way of doing this, utilising an air pump activated by an eccentric rod from the beam. He soon had a working model by 1765.

Now came a long struggle to produce a full-scale engine. This required more capital, some of which came from Black. More substantial backing came from John Roebuck, the founder of the celebrated Carron Iron Works, near Falkirk, with whom he now formed a partnership. But the principal difficulty was in machining the piston and cylinder. Iron workers of the day were more like blacksmiths than machinists, so the results left much to be desired. Much capital was spent in pursuing the ground-breaking patent. An extension of the patent was successfully obtained (James Watt's Fire Engines Patent Act, 1775 (15 Geo 3 c. 61), which in those days required an Act of parliament. Strapped for resources, Watt was forced to take up employment as a surveyor for eight years. Roebuck went bankrupt, and Matthew Boulton, who owned the Soho foundry works near Birmingham, acquired his patent rights. Watt and Boulton formed a hugely successful partnership (Boulton & Watt), which lasted for the next twenty-five years.

Watt finally had access to some of the best iron workers in the world. The difficulty of the manufacture of a large cylinder with a tightly fitting piston was solved by John Wilkinson who had developed precision boring techniques for cannon making at Bersham, near Wrexham, North Wales.

By this time, he had enclosed the top of the cylinder, using low pressure steam acting upon the vacuum in the lower part of the cylinder, unlike the Newcomen engine, which made use of atmospheric pressure. The next step was the development of a reciprocating motion, in which this process was reversed to create two power strokes.

Finally, in 1776, the first engines were installed and working in commercial enterprises. These first engines were used for pumps and produced only reciprocating motion to move the pump rods at the bottom of the shaft. Orders began to pour in and for the next five years Watt was very busy installing more engines, mostly in Cornwall for pumping water out of mines.

The field of application of the invention was greatly widened only after Boulton urged Watt to convert the reciprocating motion of the piston to produce rotational power for grinding, weaving and milling. Although a crank seemed the logical and obvious solution to the conversion Watt and Boulton were stymied by a patent for this, whose holder, James Pickard, and associates proposed to cross-license the external condensor. Watt adamantly opposed this and they circumvented the patent by their sun and planet gear in 1781.

George Stephenson

George Stephenson (9 June 1781 - 12 August 1848) was an English civil engineer and mechanical engineer who built the first public railway line in the world to use steam locomotives and is known as the "Father of Railways". The Victorians considered him a great example of diligent application and thirst for improvement, with self-help advocate Samuel Smiles particularly praising his achievements. His rail gauge of 4 ft 8½ in (1435 mm), sometimes called "Stephenson gauge", is the world's standard gauge.

Early life

George Stephenson was born in Wylam, Northumberland, 9.3 miles (15.0 km) west of Newcastle upon Tyne. He was the second child of Robert and Mabel, neither of whom could read or write. Robert was the fireman for Wylam Colliery pumping engine, earning a low wage, so that there was no money for schooling. At 17, Stephenson became an engineman at Water Row Pit, Newburn. George realised the value of education and paid to study at night school to learn reading, writing and arithmetic. In 1801 he began work at Black Callerton colliery as a `brakesman', controlling the winding gear of the pit. In 1802 he married Frances (Fanny) Henderson and moved to Willington Quay, east of Newcastle. There he worked as a brakesman while they lived in one room of a cottage. George made shoes and mended clocks to supplement his income. In 1803 their son Robert was born, and in 1804 they moved to West Moor, near Killingworth while George worked as a brakesman at Killingworth pit. His wife gave birth to a daughter, who died after a few weeks, and in 1806 Fanny died of consumption. George, then decided to find work in Scotland, and he left Robert with a local woman while he went to work in Montrose. After a few months he returned, probably because his father was blinded in a mining accident. George moved back into his cottage at West Moor and his unmarried sister Eleanor moved in to look after Robert. In 1811 the pumping engine at High Pit, Killingworth was not working properly and Stephenson offered to fix it. He did so with such success that he was soon promoted to enginewright for the neighbouring collieries at Killingworth, responsible for maintaining and repairing all of the colliery engines. He soon became an expert in steam-driven machinery

The miners' safety lamp

In 1818, aware of the explosions often caused in mines by naked flames, Stephenson began to experiment with a safety lamp that would burn without causing an explosion. At the same time, Sir Humphry Davy, the eminent scientist was looking at the problem himself. Despite his lack of any scientific knowledge, Stephenson, by trial and error, devised a lamp in which the air entered via tiny holes. Stephenson demonstrated the lamp himself to two witnesses by taking it down Killingworth colliery and holding it directly in front of a fissure from which fire damp was issuing. This was a month before Davy presented his design to the Royal Society. The two designs differed in that, the Davy's lamp was surrounded by a screen of gauze, whereas Stephenson's lamp was contained in a glass cylinder. For his invention Davy was awarded £2,000, whilst Stephenson was accused of stealing the idea from Davy. A local committee of enquiry exonerated Stephenson, proved that he had been working separately and awarded him £1,000 but Davy and his supporters refused to accept this. They could not see how an uneducated man such as Stephenson could come up with the solution that he had. In 1833 a House of Commons committee found that Stephenson had equal claim to having invented the safety lamp. Davy went to his grave believing that Stephenson had stolen his idea. The Stephenson lamp was used exclusively in the North East, whereas the Davy lamp was used everywhere else. The experience with Davy gave Stephenson a life-long distrust of London-based, theoretical, scientific experts.^[1]

Alessandro Volta

Life

Volta was born in Como and taught in the public schools there. In 1775 he became a professor of physics at the Royal School in Como; in the next year, he perfected the electrophorus, an invention that produced charges of static electricity.

In 1776 1777 he put himself into chemistry, studying atmospheric electricity and making up experiments such as the ignition of gases by an electric spark in a closed vessel. In 1779 he became professor of physics at the [University of Pavia], this was his position for 25 years. By 1800 he had developed the so-called voltaic pile, an advocate of the electric battery, which produced a steady stream of electricity.

In honor of his work in the field of electricity, Napoleon made him a count in 1810. A museum in Como, the Voltian Temple, has been built in his honor and exhibits some of the original equipment he used to conduct experiments. Near Lake Como stands the Villa Olmo, which houses the Voltian Foundation, an organization which promotes scientific activities. Volta carried out his juvenile studies and made his first inventions in Como.

Inventions and discoveries

In 1775, Volta improved and popularized the electrophorus, a device that produces a static electric charge. His promotion of it was so extensive that he is often credited with its invention, although it had actually been invented in 1764 by Swedish professor Johan Carl Wilcke^[3] In 1776-77 he studied the chemistry of gases, discovered methane, and devised experiments such as the ignition of gases by an electric spark in a closed vessel. Volta also studied what we now call capacitance, developing separate means to study both electrical potential V and charge Q, and discovering that for a given object they are proportional. This may be called Volta's Law of Capacitance, and likely for this work the unit of electrical potential has been named the volt. In 1779 he became professor of experimental physics at the University of Pavia, a chair he occupied for almost 25 years. In 1794, Volta married the daughter of Count Ludovico Peregrini, Teresa, with whom he raised three sons.

Around 1791 he began to study the "animal electricity" noted by Galvani when two different metals were connected in series with the frog's leg and to one another. He realized that the frog's leg served as both a conductor of electricity (we would now call it an electrolyte) and as a detector of electricity. He replaced the frog's leg by brine-soaked paper, and detected the flow of electricity by other means familiar to him from his previous studies of electricity. In this way he discovered the electrochemical series, and the law that the electromotive force (emf) of a galvanic cell, consisting of a pair of metal electrodes separated by electrolyte, is the difference of their two electrode potentials. That is, if the electrodes have emfs
, then the net emf is
. (Thus, two identical electrodes and a common electrolyte give zero net emf.) This may be called Volta's Law of the electrochemical series.

In 1800, as the result of a professional disagreement over the galvanic response advocated by Luigi Galvani, he invented the voltaic pile, an early electric battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. Initially he experimented with individual cells in series, each cell being a wine goblet filled with brine into which the two dissimilar electrodes were dipped. The electric pile replaced the goblets with cardboard soaked in brine. (The number of cells, and thus the voltage it could produce, was limited by the pressure, exerted by the upper cells, that would squeeze all of the brine out of the cardboard of the bottom cell.)

In announcing his discovery of the pile, Volta paid tribute to the influences of William Nicholson, Tiberius Cavallo and Abraham Bennet.^[4]

Eli Whitney, Jr.

From Wikipedia, the free encyclopedia

Eli Whitney (December 8, 1765 - January 8, 1825) was an American inventor best known as the inventor of the cotton gin. This was one of the key inventions of the industrial revolution and shaped the economy of the antebellum South.^[1] Whitney's invention made short staple cotton into a profitable crop, which strengthened the economic foundation of slavery. Despite the social and economic impact of his invention, Whitney lost his profits in legal battles over patent infringement, closed his business, and nearly filed bankruptcy.

Early life

Whitney was born in Westborough, Massachusetts, on December 8, 1765, the eldest child of Eli Whitney Sr., a prosperous farmer and his mother, Elizabeth Fay of Westborough, who died when he was 11. At age 14 he demonstrated his mechanical genius and entrepreneurial acumen, operating a profitable nail manufacturing operation in his father's workshop during the Revolutionary War.^[2] Because his stepmother opposed his wish to attend college, Whitney worked as a farm laborer and schoolteacher to save money. He prepared for Yale at Leicester Academy (now Becker College) and under the tutelage of Rev.Elizur Goodrich of Durham, Connecticut he entered the Class of 1789.^[1]

Whitney expected to study law but, finding himself short of funds, accepted an offer to go to South Carolina as a private tutor. Instead of reaching his destination, he was convinced to visit Georgia.^[2] In the closing years of the eighteenth century, Georgia was a magnet for New Englanders seeking their fortunes (its Revolutionary era governor had been Lyman Hall, a migrant from Connecticut). When he initially sailed for South Carolina, among his shipmates were the widow and family of Revolutionary hero, General Nathanael Greene of Rhode Island. Mrs. Greene invited Whitney to visit her Georgia plantation, Mulberry Grove. Her plantation manager and husband-to-be was Phineas Miller, another Connecticut migrant and Yale graduate (Class of 1785), who would become Whitney's business partner.

Whitney is most famous for two innovations which later divided the United States in the mid-19th century: the cotton gin (1793), and his advocacy of interchangeable parts. In the South, the cotton gin revolutionized the way cotton was harvested and reinvigorated slavery. While in the North, the adoption of interchangeable parts revolutionized the manufacturing industry, and in time contributed greatly to their victory in the Civil War.^[3]

Career inventions

Interchangeable parts

Though Whitney is popularly credited with the invention of a musket that could be manufactured with interchangeable parts, the idea predated him. The idea is credited to Jean Baptiste Vaquette de Gribeauval, a French artillerist, and credits for finally perfecting the "armory system," or American system of manufacturing, is given by historian Merritt Roe Smith to Captain John H. Hall and by historian Diana Muir writing in Reflections in Bullough's Pond to Simeon North. In From the American System to Mass Production, historian David A. Hounshell described how de Gribeauval's idea propagated from France to the colonies via two routes: from Honoré Blanc through his friend Thomas Jefferson, and via Major Louis de Tousard, another French artillerist who was instrumental in establishing West Point, teaching the young officer corps of the Continental Army, and establishing the armories at Springfield and Harpers Ferry.

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