TRANSACTIONS OF SECTION G. 785 



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 extends 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 Lehigb Valley Railway, in the United 

 States, such a system of telegraphing without wires is in actual daily use. 



The conduct of telephonic business in England is still in the hands of those 

 who bold 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 sub- 

 scribers in and about New York ; while the number in London is only 4,851. 



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 uniform without irri- 

 tating 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 unduly heat the room. 



In the Post Office Central Savings Bank in London it has been found, after two 

 years' experience of electi-ic lighting, that the average amount of absences from illness 

 lias 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 3,349/. and the annual cost of working 700/. per annum, say a 

 total annual cost of 1,034/. 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 7^^ part of a horse-jmwer. 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 



„ was 



» » sperm „ 



„ „ mineral oil „ 



„ „ vegetable oil ,, 



„ „ coal gas „ 



,) „ cannelgas „ 



,1 ,1 electricity (glov?) „ 



,, „ electricity (arc) ,, 



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 Jablochkoft" and Bi-ush showed how to light up our streets effectually 

 and practically ; it was not ttntil 1881 that Edison and Swan showed how our 

 homes could be illuminated softly and perfectly. ' Unpreparedness for such a revo- 

 lution produced a perfect panic among gas proprietors ; inexperience in the use of 

 powerful electric currents resulted in frequent failure and danger ; speculation in 

 1888. 3e 



