496 



NATURE 



[Sept. 20, 1888 



prosperity of the world. The engineer, however, feels that 

 steam and electricity in his hands have done more to economize 

 labour, to cheapen life, to increase wealth, to promote inter- 

 national friendship, to alleviate suffering, to ward off war, to 

 encourage peace, than all the legislation and all the verbosity of 

 the politician. 



The railways of this country are entirely dependent for the 

 conduct of their traffic on the telegraph, and the security of their 

 passengers is mainly due to the working of the block system. A 

 railway — say between London and Bath — is broken up into 

 certain short sections, and only one train is allowed on one sec- 

 tion at one time. The presence, motion, and departure of trains 

 are announced and controlled by electric signals, and the out-door 

 signals are governed by these electric signals. There are few 

 more interesting places to visit than a well-equipped signal-box 

 on one of our main railways. The signalman is able to survey 

 the lines all around and about him by aid of his electric signals ; 

 he can talk by telegraph or by telephone to his neighbours and 

 his station-master ; he learns of the motion of the trains he is 

 marshalling by the different sounds of electric bells ; he controls 

 his out-door signals by the deflection of needles, or the movement 

 of miniature semaphores ; he learns the true working of his distant 

 signals by their electrical repetition ; machinery governs and 

 locks every motion he makes, so that he cannot make a mistake. 

 The safety of railway travelling is indicated by the fact that, 

 while in the five years ending 1878 thirty-five people were killed 

 annually from cause* beyond their own control, in the five years 

 ending 1887 the average has been reduced to sixteen. One 

 person is killed in 35,000,000 journeys made by train. Wherever 

 we are dependent on human agency we are subject to human 

 error, and a serious accident very recently at Hampton Wick 

 has shown how the most perfect machinery may be rendered 

 valueless to protect life when perversity, thoughtlessness, or 

 criminality enter as factors into the case. 



At the meeting of the Association in Plymouth in 1877, I was 

 able for the first time in this country to show the telephone at 

 work. Since then its use has advanced with giant strides. 

 There are probably a million instruments at work now through- 

 out the civilized world. Its development has been regularly 

 .chronicled at our meetings. As far as the receiving part of the 

 apparatus is concerned, it remains precisely the same as that 

 which I brought over from America in 1877 ; but the transmitter, 

 ever since the discovery of the microphone by Hughes in 1878, 

 has been entirely remodelled. Edison's carbon transmitter was 

 a great step in advance ; but the modern transmitters of Moseley, 

 Berliner, D'Arsonval, De Jongh, leave little to be desired. The 

 disturbances due to induction have been entirely eliminated, and 

 the laws regulating the distance to which speech is possible are 

 so well known, that the specification of the circuit required to 

 connect the Land's End with John o' Groats by telephone is a 

 simple question of calculation. A circuit has been erected be- 

 tween Paris and Marseilles, 6oo miles apart, with two copper 

 wires of 6J gauge, weighing 540 pounds per mile, and conversa- 

 tion is easily maintained between those important cities at the 

 cost of three francs for three minutes. One scarcely knows 

 which fact is the more astounding — the distance at which the 

 human voice can be reproduced, or the ridiculously simple ap- 

 paratus that performs the reproduction. But more marvellous 

 than either is the extreme sensitiveness of the instrument itself, 

 for the energy contained in one heat unit (gramme-water-degree) 

 would, according to Pellat, maintain a continuous sound for 

 10,000 years. 



The influence which electric currents exert on neighbouring 

 wires extend to enormous distances, and communication between 

 trains, and ships in motion, between armies inside and outside 

 besieged cities, between islands and the main-land, has become 

 possible without the aid of wires at all, by the induction which 

 is exerted through space itself. On the Lehigh Valley Railway, 

 in the United States, such a system of telegraphing without 

 wires is in actual daily use. 



The conduct of the telephonic business in England is still in 

 the hands of those who hold the patents, and who maintain a 

 most rigid monopoly. These patents have only a short period 

 to run, and when they expire we may expect to find that England 

 will not occupy the very retired position she holds now as a 

 telephone country. Stockholm has more subscribers than 

 London ; there are 15,000 subscribers in and about New York, 

 while the number in London is only 4851. 



Electric lighting has become popular, not alone from the 

 beauty of the light itself, but from its great hygienic qualities in 



maintaining the purity and coolness of the air we breathe. The 

 electric light need not be more brilliant than gas, but it must be 

 more healthy. It need not be cooler than a wax candle, but it 

 must be brighter, steadier, and more pleasant to the eye. In 

 fact, it can be rendered the most perfect artificial illuminant at 

 our disposal, for it can illumine a room without being seen 

 directly by the eye ; it can be made absolutely steady and uni- 

 form without irritating the retina ; it does not poison the air by 

 carbonic acid and carbonic oxide, or dirty the decorations by 

 depositing unconsumed carbon ; it does not destroy books or 

 articles of vertu and art by forming water which absorbs sulphur 

 acids ; and it does not unnecessarily heat the room. 



In our Central Savings Bank in London it has been found, 

 after two years' experience of electric lighting, that the average 

 amount of absences from illness has been diminished by about 

 two days a year for each person on the staff. This is equivalent 

 to a gain to the service of the time of about eight clerks in that 

 department alone. Taking the cost at the "overtime" rate 

 only, this would mean a saving in salaries of about ^640 a year. 

 The cost of the installation of the electric light was .£3349, and 

 the annual cost of working ^700 per annum, say a total annual 

 cost of ^1034. The cost of the gas consumed for lighting 

 purposes was about ^700 a year, so that on the whole there 

 was a direct saving of something like ^266 a year to the 

 Government, besides the material advantage of the better work 

 of the staff resulting from the improved atmospheric conditions 

 under which their work is done. 



The production of light by any means implies the consumption 

 of energy, and this can be measured in watts, or the rate at 

 which this energy is consumed. A watt is T j 5 part of a horse- 

 power. It is a very convenient and sensible unit of power, and 

 will in time replace the meaningless horse- power. 



One candle light maintained by tallow . . . absorbs 124 watts. 



,, ,, wax ....,, 94 ,, 



,, ,, sperm . . . ,, 86 ,, 



,, ,, mineral oil ,, 80 ,, 



,, ,, vegetable oil . ,, 57 ,, 



,, ,, coal gas . . . „ 68 ,, 



,, ,, cannel gas . . ,, 48 ,, 



,, ,, electricity (glow) ,, 3 ,, 



,, ,, electricity (arc) ,, 55 >» 



The relative heat generation of these illuminants may be estimated 

 from these figures. 



Though the electric light was discovered by Davy in 1810, it 

 was not until 1844 that it was introduced into our scientific 

 laboratories by Foucault ; it was not until 1878 that Jablochkoff 

 and Brush showed how to light up our streets effectually and 

 practically ; it was not until 1881 that Edison and Swan showed 

 how our homes could be illuminated softly and perfectly. Un- 

 preparedness for such a revolution produced a perfect panic among 

 gas proprietors ; inexperience in the use of powerful electric 

 currents resulted in frequent failure and danger ; speculation in 

 financial bubbles transferred much gold from the pockets of the 

 weak to the coffers of the unscrupulous ; hasty legislation in 1882 

 restricted the operations of the cautious and the wise ; and the 

 prejudice arising from all these causes has perhaps fortunately, 

 delayed the general introduction of electricity ; but now legislation 

 has been improved, experience has been gained, confidence is 

 being restored, and in this beautiful town of Bath fifty streets are 

 about to be lighted, and we see everywhere around and about us 

 in our English homes the pure glow-lamp replacing filthy gas 

 and stinking oil. The economical distribution of the electric cur- 

 rent over large areas is annually receiving a fresh impetus. The 

 expensive systems defined in the Act of Parliament of 1882 have 

 entirely disappeared. Hopkinson in England, and Edison in 

 America, showed how a third wire reduced the weight of copper 

 needed by 66 per cent. Gaulard andGibbs in 1882 showed how 

 the conversion of alternate currents of high electromotive force 

 to currents of low electromotive force by simple induction coils 

 would enable a mere telegraph wire to convey sufficient electricity 

 to light a distant neighbourhood economically and efficiently. 

 Lane Fox in 1879 showed how the same thing could be done by 

 secondary batteries ; and Plante, Faure, Sellon, and Parker have 

 done much to prove how batteries can be made to solve the 

 problem of storage ; while King and Edmunds have shown how 

 the distribution by secondary batteries can be done as economic- 

 ally as by. secondary generators. The Grosvenor Gallery Com- 

 pany in London have proved the practicability of the secondary 

 generator principle by nightly supplying 24,000 glow-lamps 



