Thus are the candles which Mr. COOK used to employ, and which cost him three shillings a day, entirely superseded. But, besides his expence in candles, oil and cotton for soldering, used to cost him full 30_l._ a year; which is entirely saved, as he now does all his soldering by the gas flame only. For “in all trades in which the blow-pipe is used with oil and cotton, or where charcoal is employed to produce a moderate heat, the gas flame will be found much superior, both as to quickness and neatness in the work: the flame is sharper, and is constantly ready for use; while, with oil and cotton or charcoal, the workman is always obliged to wait for his lamp or coal getting up; that is, till it is sufficiently on fire to do his work. Thus, a great quantity of oil is always burned away useless; but, with the gas, the moment the stop-cock is turned, the lamp is ready, and not a moment is lost.” We must refer to Mr. COOK’s letter for the details of expence, which he gives with faithful minuteness, and always leaning to the side unfavourable to the gas. The result of the whole is, that he saves 30_l._ out of the 50_l._ which his lights formerly cost him: and, when we consider that his calculation allows the gas-lights to burn the whole year, and the candles only twenty weeks, there can be little doubt, that the savings in this case follow nearly the same proportion as in the former. If the apparatus be erected even on a smaller scale, “the saving,” Mr. COOK assures us, “will still be considerable: for the poor man, who lights only six candles, or uses one lamp, if the apparatus is put up in the cheapest way possible, will find it only cost him 10_l._ or 12_l._ which he will nearly, if not quite, save the first year.” Mr. ACKERMAN having, in this town, set the example of lighting his establishment with gas, several other individuals soon followed the attempt. The following statement will show, that this species of light may be made use of with the greatest advantage, upon a still smaller scale, where no great nicety with regard to the apparatus for procuring gas is required. The following report I have received from Messrs. LLOYD, of Queen Street, Southwark, thimble manufacturers and whitesmiths, who have used the gas-light for soldering and other purposes these five years past.