THE ELECTEIC LIGHT.

Thames Star, Volume VIII, Issue 2836, 18 March 1878, Page 2

THE ELECTEIC LIGHT.

In a paper on " Some Becent Improvements in Dynamo-Electric Apparatus," by Pr Higgs, and Mr Brittle, the practical application of Faraday's discovery of magnetic-electricity was stated to be the origin of the present powerful dynamoelectric machines. A description was then given of the latest construction of the Sieman's dynamo-electric machine and electric lamp, the latter devised specially ;fpr lighthouse illumination, similar lamps being about to be supplied to the Lizard lighthouse. The magnetoelectric machines first employed in lighthouse illumination, as' poin'ed out by Dr Tyndall, bore a cost of 10 to one as com* pared with the latest dynamo machine, while the cubic spaces occupied were as 25 to one, and the weights as 13 7 to one; the total light power produced for the condensed beam of light bein* about one to fire. Thus, with a cost 10 times, with a weight 14 times, and a volume 25 times that of llie latest construction, the old machines produced one-fifth of the light with an expenditure of practically the name driving power. Much excitement had been evinced as to the probable competition between gas and electricity as sources of light power. Although, under certain circumstances, these two agents I undoubtedly came into competition, they ! had separate fields. Hitherto gat had j been employed for spaces of both large and small dimensions,.because a better source of light for large spaces had not! been procurable with economy ; but for lighting large spaces not subdivided by opaque objects or screens it was a want of economy to employ gas. Assuming the light power proportional to horse power expended, 100-horse power would fcive 160,000 candles' light; distributed from three points the post would not be more than $1 gs GJ per hour, each light centre giving au illumination which -would enable small print to be read at a distance of.a quarter of a

mile. For large spaces the cost of electric lighting was about one-fourth, or even one-fifth that of gas lighting, when steam had been used as power and wear and tear were reckoned. With a gas engine as motor the ratio had only been as 1 to 5, the greatest economy having been with a turbine as motor. If, however, the ratio of light intensities were adopted as that ratio of efficiency, the advantage would be considerably higher (20 to 1) in favour of eleetrie lighting. It might be laid down as proved by experience that for lighting large spaces not too much subdivided the advantage was greatly in favour of electric light, but that where numerous light centres of small intensity were required, or where the space was much subdivided, the advantage was in favour of gas. This advantage would cease when a practical method of subdividing the electric light was obtained.--Times.