The following letter has been addressed to the Editor of the Journal of Gas Lighting, de., by Ur, Lewis Thompson aya wore ended, yet I now find myself com-Smx,—although I had a hope that my gus pelled to seek refuge from labour by again taking up the pen upon the subject of gas lighting. In point of fact, ea many persons have lately begged of me to favour them with my opinions upon the relative merit of electric light as compared with ga light, that I tara to your pages as therenliet move of meeting and stopping the demand made upon though cannot avoid sayi mit as the subject has yet be it seems that the most econom: trio lighting is obtained by an electric Lump, worked by one-horse power, and producing a light equal to 700 spermaceti candles; but any attempt to diminish thie light is followed by a rapid increase in the comparative cost; so that, for all practical purpose in oon hole hog," whilst the gas light la In truth, the two lights have as yet no kind of rivalry, from x domestic or consumer's point of view;-nor have any facts been developed electric light atelligible here, T must permitted 6 aay afew words about light it-that in' these" reniarke preference' to the undulatory theory:" Thins regarded, light exists under two forms, which may be called "quantity" and "intensity," and these forms cannot be made to "pass into or substitute each other thus no amount' of red-hot charcoal can ever produce a light having an intensity equal to the light of the eu; nor can the sun's rays be a0 modified as to give a light similar to that of red-hot charcoal. The first form, or quantity of light," depends upon the number of particles of light in motion; the second form, or "intensity of light," depends upon the velocity with which these particles revolve around their own axes; ao that light has two motions, whick may be compared to the annual and diurnal motions of the earth, better, to the motions of a et. Tu passing from one point to another, each particle of light travels at a rate which ins been estimated as equal to 170 000 miles por second, but whilst so travelling it revolves or spins upon its axis with greater or less rapidity, and it is the rate of this rapidity which gives rise to the intensity of the light.' Undervall circumstances the travelling rate of light is uniform, but'the revolving or spinning rate may vary greatly; and it is most likely thie spinning motion which acts upon the-organ of vision in animals, #0 that it is quite possible for a certain rate 'o produce no sction—or darkness—upon the eye of one animal, and yet act strongly so produce clear in the eye of another animal. 'The perfection of a light for uiman use would seem to be a combination of great quantity, with such "intensity: as' the' optic the' human retina ix capable: of bear-ithout st idence has 6 area of the forts of a focus, and thus protect the ner or'retina from violence. Now, it is only when the particles of light are'travelling in' lines parallel to each other that they oan be reduced' to-s small focus equal to the size of this yellow apot—a condition beautifully secured by the great distance of the cun, which readers all the parallel, but which can never be obtaine' any terrestrial light, la consequence of its near proximity to the eye or organ of visi In all kinds of asta light, therefore, the mud yet been produced; and, if produced by any of the electri now in-use, it would be found to b ly expensive, and would far exceed the cost even of wax and spermac Under these circumstances, it seems, at Jeast, to me, that no kind of riv petition ought to exist between gas lighting, for the electric light, i comes into rise, can only do a0 og a kind of wholesale light, or dealer in large quantities, whilst the gas-maker is content to supply the Tots; in short, the one elfers nothing less han million mall or large quantities in small 700 candles, and the other anything you please, down to one candle.
But, turning in another direction, by way of comparison, we may remark that for one per-sou who wants to buy a whole sheep, there are ten thousand persons who require only a mutton chop; consequently, the retail butcher does not find himself in competition with the cattle dealer; or, if we are to speak in Yankee phraseology, we inay say that the electric Light ight, 80 that the rays of artificial light are not confined to the yellow pot or chield of the retina, but spread over irface of the optic nerve, an: thas create at frat a sense of irritation, then a feeling of weariness, and ultimately of exbauation or dimness of eight, whi Tong continued, ends in paralyse called by surgeons, mauros the only disease podvc.ed by for the divergeuct of the. rays tional Pu the refrac powers of the oryatalline wens, thus: giving rise to a chronic inflammation, whith lends to that form of opaque deposit i cataract avd these evil see are canted by the want of two conditions that exist in Joler light—Gret, the near proximity of artificial light, as compared with solar light, carists great divergence or radial tion; secondly, the small area of artificial light, compared with the solar area, adds itumeveely to that divergence, and thus greatly increases the evil. If 1 qas asked whether I would prefer the light from 15 spermadeti candles to plaints about-bad'traide, declitiing profits, and macofi candles, L-wottld say in-a.moment, 'Give' me the candles," because tio. luminiforous aresof the candles is muck greater than that of the gas-burner, and, moreover, the intensity or whiteness of the light is lees in the candles than in the gas light, consequently it will irritate the eyeless, But, if I would thus prefer a candle to a gas light, what must Tsay to an electric light, in which the luminiferous ig. a mere speck, and the intensity of the light enormous? My answer is Sucha ight is altogether-unfit-for domestic use; and if ever it is generally adopted, I'venture to predict that cxaes of amaurosis and cataract will be as plentiful as blackberries in autumn, course, is only my unsupported but there I am content to leave the question, Lawis Taoursow, August 28th, 1878.
Text read from the printed page and cleaned; old type leaves the occasional error.