The Invention of the Telegraph

It took the genius of Gauss, probably the greatest mathematician who ever lived, to see the proper importance of the discoveries of Oersted: electric current – magnetic needle – telegraph. Gauss and his friend and colleague Professor Weber began experimenting on these lines and in 1832 the needle telegraph was completed. However, neither Gauss nor Weber had the time or inclination to concern themselves with the practical development of the electric telegraph. Samuel Morse, born in 1891 in Charlestown, Massachuchetts, after graduating from Yale, travelled through Europe in the late 1820s to study the various schools of painting in the countries of their origin. During these travels he became deeply impressed by the electro-magnetic experiments carried out in Europe, and during his return journey to the USA in 1832 he devised a new type of telegraph. In those days, there were vast technical difficulties which cannot easily be appreciated in our time. For instance, there was no such thing as insulated copper wire. Inventive as ever, Morse used the wire (insulated) used by New York milliners to make fashionable hats for society ladies. Morse did not use the magnetic needle; instead he employed an electro-magnet to press a pen against a paper strip which was unrolled slowly and uniformly. Short impulses on the transmitter resulted in dots on the strip and long impulses in dashes. Combinations of dots and dashes represented letters, numbers, and symbols; this was the Morse code, patented in 1840. With this apparatus Morse telegraphed, in his first tests in 1837, over a distance of ten miles. For six years he worked to improve his technique and his code, whereupon Congress in 1843 approved the installation of the world’s first telegraph line between Washington and Baltimore at a cost of $30,000. The line was officially taken into use on 24 May 1844. Werner von Siemens built the first telegraph connection in Europe (between Berlin and Frankfurt-am-Main) which was taken into use in 1849. Von Siemens still used the needle telegraph which he had improved. However, by the early 1850s the Morse telegraph system had became accepted worldwide as the (then) only reliable means of communication over long distances. When Morse died in 1872, the telegraph had already girdled the earth. At about the same time, the English physicist John Daniell developed a new primary battery, which is still in use and named after him. It is a non-polarizing cell with zinc (negative) and copper (positive) electrodes. The zinc plate is in a porous cup containing a weak zinc-sulphate solution; the cup is in a jar filled with a saturated copper sulphate solution in which the copper electrode is immersed. The e.m.f. of the cell is about 1.1 V. Another aspect of electricity that had the attention of researchers and technologists was lighting. The world had to wait for the incandescent lamp developed by Edison later in the century, but nevertheless in the middle of the century New York, London, Paris, Berlin, and some other cities had a kind of electric lighting in some important thoroughfares provided by arc lamps.

Continue Reading

Ancient Inventions in Electronics

In 1837, the first electric motor was developed (and patented) in the USA by Thomas Davenport. A few years later, in 1839, the magnetohydrodynamic battery was proposed by Michael Faraday in the UK; the photovoltaic effect was described in France by Alexandre Edmond Becquerel (1820–91), and the fuel cell was invented by Sir William Robert Grove (1811–96) in the UK. In 1843, the Scottish inventor Alexander Bain patented what has become known as facsimile reproduction (fax), and in 1845–47 the German physicist Gustav Robert Kirchoff (1824–87) published the two famous laws that are named after him. In 1847, George Boole (1815–64) published his first ideas on symbolic logic, although his major work, Investigation of the Laws of Thought was not published until 1854. The kind of symbolic algebra that Boole developed led to Boolean algebras, which are, of course, of great significance in modern algebra and computing. In 1852, thin film technology was introduced by Sir William Robert Grove. In 1860, professor T J Wray gave a public demonstration of the mercury arc lamp on the Hungerford Bridge in London, and in Germany, the physicist Johann Philipp Reis (1834–74) developed the first microphone. Unfortunately, this microphone was considered a toy and quickly forgotten. Another important contribution to electrical technology came from the French physicist Robert Louis Gaston Planté (1834–89), who in 1859 developed the lead-acid cell, which was the world’s first practical rechargeable or secondary battery. In fact, the lead-acid battery is even today the most widely used rechargeable battery in the world. In the same year, Michael Faraday discovered that silver sulphide possesses a high negative temperature coefficient. This discovery forms the basis of what are now termed thermistors, that is, temperature-sensitive non-linear resistors. The name thermistor was coined by the Bell Telephone Laboratories of the USA during their research into materials for these components. Also in that year, one of the century’s foremost experimentalists, the English physicist James Prescott Joule (1818–89) described magnetostriction, a phenomenon in which the mechanical dimension of a magnetic material is altered as the magnetization is varied. Perhaps the most able theoretician of the 19th century, the Scottish physicist James Clerk Maxwell (1831–79), started his monumental research on electromagnetism in the late 1850s. This laid the foundations for the work of the German physicist Heinrich Rudolph Hertz (1857–94) in discovering radio waves. Maxwell’s ‘equations’ (1864) form fundamental laws of theoretical physics that govern the behaviour of electromagnetic (radio; television) waves in all practical situations. The equations are used to analyse the propagation of radio waves in free space, at all sorts of boundary, and in all guided-wave structures or transmission lines. His field equations are mathematical formulations of the laws of Gauss, Faraday and Ampère from which the theory of electromagnetic waves can be derived. The Maxwell bridge can be used for the measurement of capacitance and inductance. Maxwell’s Rule states that every part of an electric circuit is acted upon by a force tending to move in such a direction as to enclose the maximum magnetic flux.

Continue Reading

When Electronics Was Young

The year 1831 was noteworthy for a number of reasons, none of them as yet connected with electronics per se: 1. Sir David Brewster (1781–1868) publishes his ‘Treatise on Optics’; 2. Independently, Michael Faraday (1791–1867) and Joseph Henry (1797–1878) discover that electricity can be induced by changes in a magnetic field—a discovery leading to the first electric generators; 3. Joseph Henry describes a practical electric motor; 4 Sir Charles Wheatstone (1802–1875) and William Fothergill (1799–1868) create the first printing telegraph, a machine with an arrow that points to letters of the alphabet; 5. The British Association for the Advancement of Science is established 6. Charles Darwin (1809–1882) begins his epic five-year voyage on the Beagle 7. An otherwise obscure von Jacobi discovered that the Earth may be used as a conductor. Von Jacobi’s discovery is, of course, of great importance in electrical engineering. Yet, neither his name nor his discovery is mentioned in most modern reference books. In that year, Faraday argued that, since Oersted had shown that a current could produce a magnetic field, a magnetic field should produce a current. He found this to be so, discovering the important property of electromagnetic induction (earlier discovered by Joseph Henry). In this work, Faraday introduced the idea of lines and fields of force, an idea which was to prove highly productive. It enabled him to devise primitive motors, a transformer, and a dynamo. Faraday also examined capacitors and the properties of dielectrics. Electromagnetic induction, the conversion of magnetism into electricity, had been discovered in 1830 by Joseph Henry, but Henry had not published his findings. In 1832, he discovered self-induction and this time he published immediately. Consequently, the unit of self-induction is named after him. A coil has a self-inductance of one henry (H) if a change of current through it of one ampere per second produces a back emf of one volt across it. Sir Charles Wheatstone who popularized but did not invent the bridge named after him (it was invented by S Christie) developed, together with Cooke, a device with separate control and switching sections. However, the first patent for such a relay (as it came to be known) was taken out by Edward Davy in 1838, although Cooke and Wheatstone’s patent was also accepted. Samuel Morse was granted a US patent in 1840 which is apparently similar to Davy’s patent. Samuel Finley Breese Morse (1797–1872) made use of relays to develop the binary (on-off) telegraph system, which he put into practice in 1844 after he obtained a government grant to connect Baltimore and Washington DC. Electrical telecommunications had been borne.

Continue Reading

Transatlantic Telecommunications Cables

After Morse had instigated the world’s first telegraph line in 1843, practical men developed this new means of communications, and constructed improved and more reliable equipment. Before long overland lines were no longer sufficient and intercontinental lines were proposed. In 1850, a cable was laid between Dover and Calais. A similar operation failed when it was first tried in the Mediterranean (between Sardinia and Algeria), owing to that sea being much deeper in places than the English Channel. Only in 1857 did Newall & Co, with Werner von Siemens as adviser, achieve success and the first deep-sea cable was laid. Following this success, the Agamemnon and Niagara, cable-laying ships of the London-based Atlantic Telegraph Company, laid 4,000 miles of cable linking Europe and America. When the work was completed in August that year, Queen Victoria and President Buchanan exchanged telegrams of congratulation. Three weeks later, the connection was suddenly interrupted and the telegraph machines stopped;  it seems likely that moisture had penetrated the insulation of the cable. The fault was never found; to this day the cable lies at the bottom of the Atlantic. It took many years before funds had been raised to attempt another trans-Atlantic cable. This was undertaken by the newly formed Telegraph Construction and Maintenance Company, using the biggest ship then afloat – the Great Eastern. This paddle steamer had a complement of 500 men, including 120 engineers and technicians of the cable company. It took five attempts, but in 1866 the permanent link between Europe and America was finally established. By the end of the 19th century more than 250,000 miles of cable had been laid, establishing well over 300 links. Today, just over a century later, the cable link between France, Great Britain and the United States, finished in 1988, consists of a single fibre-optic cable, TAT-8, which is 4114 miles (6620 km) long, and carries most of the television, telephone, and data processing signals between these countries. An even later one (1992), TAT-10, is a direct 4436 mile (7320 km) long fibre-optic link between the USA and Germany via the Netherlands. Of course, not everybody involved in physics and electrical engineering during the 19th century was concerned with cable-laying. In 1856, Ernst Werner von Siemens (1816–92) demonstrated a small, manually-operated dynamo that used a permanent magnet, and in 1866, the series dynamo. It was not until the Belgian-French inventor Zénobe Théophile Gramme (1826–1901) had built the first commercially practical generator for producing alternating current in 1867, however, that the world’s first public electrical power plant could be taken into use (in Godalming, England, in 1881). The alternator used in this plant, manufactured by the firm of Siemens & Halske, developed 746 kilowatts. In 1879, in America, Thomas Alva Edison (1847–1931) and in England, the British physicist and chemist Sir Joseph Wilson Swan (1828–1914) simultaneously introduced the first practical carbon filament lamp, which was a great improvement on the mercury arc lamp first demonstrated by Professor Wray on the Hungerford Suspension Bridge in London on 3 September 1860.

Continue Reading