A TREATISE ON GAS-I.IGHT.

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deranged, without being immediately extin-guished. Besides, the gas-light flames emitno sparks, nor are any embers detached fromthem. As a proof of the comparative safetyof the gas-lights, it need only be stated, thatthe Fire-offices engage themselves to insurecotton-mills, and other public works, at a lesspremium, where gas-lights are used, than inthe case of any other lights.* The excessiveexpence of insurance arising from the nume-rous candles employed in most of the first ratemanufactories, and the combustible nature ofthe structure of the buildings ; the great diffi-culty of retrieving the injury resulting to awell-organised business, from the accidentaldestruction of the machinery, are objectsalone sufficient to furnish the strongest eco-

* Since the preceding pages have been printed, I haveseen a self-extinguishing gas-lump , invented by Mr.Ci.EGG.This lamp is so constructed, that the gas cannot flow to theburner, when the flame becomes extinguished. If, therefore,the lamp should be blown out, and the stop-cock wiiichsupplies the gas be left open, the extinction of the flamewill effectually shut the valve. The action of this lamp de-pends upon the expansibility of a metallic rod, heated bythe flame of the lamp, and thus keeping open the valve,whereas, when the lamp is extinguished, and the rod be-comes cold, it contracts to its natural dimensions, and, bythat means, effectually closes the valve. The same engineerhas invented a machine, which both measures and registers,

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