240 



NATURE 



[November 6, 1919 



to which the term "dynamo" was later 

 on applied. In 1870 Z. (iramme, a French 

 electrician, re-invented a special form of 

 armature- construction, first suggested by 

 Pacinotti, which enabled a dynamo to give a very 

 uniform direct electric current ; and Hefner 

 Alteneck, in Germany in 1873, had patented 

 another type of armature winding, now called 

 the drum winding. The way was then opened 

 for the production of electric currents by 

 mechanical power on a large scale and for the 

 solution of the problem of public electric lighting. 



Paul Jablochkov invented in 1876 his "electric 

 candle " and initiated public street electric light- 

 ing in Paris. C. F. Brush, in America, invented 

 a simple form of arc lamp adapted for working 

 in series with others and a type of series arc- 

 lamp dynamo. This Brush system soon after 

 1878 was largely in operation for street lighting. 



In the following year Edison, in .America, and 

 Swan, in England, solved the problem of the pro- 

 duction of a practical carbon filament incandescent 

 electric lamp and thus rendered domestic electric 

 lighting possible on a large scale. 



In the same year the writer of this article 

 exhibited some of Edison's early carbon filament 

 lamps in operation in Queen Victoria Street, 

 London, though it was not until the Crystal 

 Palace Electrical Exhibition of 1882 that the 

 public saw the new illuminant used on a large 

 scale. The invention of the metallic filament lamp 

 about 1904 made an immense improvement in 

 economy in electric illumination, and more recently 

 the "half watt" gas-filled lamp threatens to dis- 

 place arc lighting entirely from streets and build- 

 ings. 



The utilisation of this lamp, however, 

 required a public electric supply, and Edison was 

 one of the first to work out all the practical 

 details and provide a complete system. This was 

 put into operation in New York and in London 

 in 1882. Improvements in the dynamo rapidly 

 followed, and in the hands of J. Hopkinson, 

 Crompton, Siemens, and others it became a highly 

 efficient machine. About 1883 attention began 

 to be directed to alternating currents, and alter- 

 nators and transformers vi'ere designed by Fer- 

 ranti, Mordey, and Parker. 



In or before 1890 or 1891 polyphase alternators 

 were first produced by Ferraris, Tesla, and 

 C. E. L. Brown. Large electric supply stations 

 were then built, and a lively contest took place on 

 the relative merits of direct and alternating cur- 

 rents. The polyphase alternating system has, how- 

 ever, enabled electric power transmission to be 

 conducted over great distances, and in the last 

 twenty-five years an immense utilisation of 

 natural water-power has taken place by this 

 means, beginning with the Niagara Falls Power 

 Station in 1893. Electrification of urban tram 

 lines and short-distance inter-urban railways has 

 made enormous progress in the last quarter of a 

 century. 



Meanwhile, between 1876 and 1879 Graham 

 Bell, Edison, and Elisha Gray, in the United 

 NO. 2610, VOL. 104] 



States, had given us the speaking telephone, and 

 D. E. Hughes, in England, had produced the 

 microphone, which is the basis of all modern . 

 telephone transmitters. In 1876 Lord Kelvin 

 astonished the British Association at Glasgow by 

 the information that he had heard articulate 

 speech transmitted over a wire by one of Bell's 

 early telephones. In 1S79 the first rudimentary 

 telephone exchange was established in London. 



When once the commercial possibilities of 

 telephone exchanges and of domestic electric 

 lighting had been realised, progress was assured, 

 although that of the latter was retarded by the 

 unwise Electric Lighting Act of 1882, not repealed 

 until 1888, and telephonic improvements were 

 hindered by the Government control of it estab- 

 lished by the legal interpretation of the term 

 "telegraph" to include "telephone," under the 

 Telegraph Purchase Acts. 



Limiting consideration, then, to improvements 

 in telegraphy and telephony, we note very briefly 

 the following stages of invention. In i86g the 

 British Government passed an Act for the 

 acquirement of the electric telegraph companies, 

 and made the transmission of paid messages a 

 public service. This " nationalisation " has, how- 

 ever, put a burden on the taxpayer, although it 

 resulted in great extension of the facilities. Im- 

 proved methods of transmission, such as the 

 Wheatstone automatic system, capable of send- 

 ing 400 words a minute, were soon introduced 

 for Press purposes. 



So far back as 1855 D. E. Hughes had in- 

 vented an ingenious printing telegraph, but 

 immense improvements afterwards introduced 

 by Baudot, Creed, and Murray now enable twelve 

 messages to be sent simultaneously on a single 

 wire, each being printed down on paper at the 

 receiving end, the sending being done by a typist 

 on a special typewriter at the rate of thirty to 

 forty words a minute. 



Most long telegraph lines are now worked multi- 

 plex, meaning that several messages can be sent 

 in the same or opposite directions on the same 

 wire simultaneously. 



In submarine cable work Great Britain has 

 always been pre-eminent. The first submarine 

 cable was laid in 1851 by the Brothers Brett 

 across the English Channel, and the first per- 

 manently successful Atlantic cable by Sir Charles 

 Bright and Sir James .Anderson in 1866 from 

 the s.s. Great Eastern. Lord Kelvin, who had 

 previously given to the world his mirror galvano- 

 meter, invented also in 1867 the syphon recorder 

 which receives and records the feeble arrival 

 currents, and later improvements have given 

 to it its present form. Very sensitive relays 

 and repeaters have been invented by Muir- 

 head, Heurtley, S. G. Brown, and Axel 

 Orling, which have vastly increased the speed 

 of transmission. Lord Kelvin laid the firm 

 foundations for the theory of the telegraph cable^ 

 so far back as 1855. There are at present aboul^ 

 300,000 miles of working submarine cable in the 

 world, most of which has been made and laid' 



