Another manufacturer who was one of the first that adopted the use of this method of illumination in the small way, and who gave a statement of its advantages to the public, is Mr. COOK, a manufacturer of metal toys, at Birmingham, a clear-headed, prudent man, not apt to be dazzled by a fanciful speculation, but governed in his transactions by a simple balance of profit and loss. There is a _naïveté_ in his own account of the process which will amuse as well as instruct the reader. “My apparatus is simply a small cast-iron pot, of about eight gallons, with a cast-iron cover, which I lute to it with sand. Into this pot I put my coal. I pass the gas through water into the gasometer or reservoir, which holds about 400 gallons; and, by means of old gun-barrels, convey it all round my shops. Now, from twenty or twenty-five pounds of coal, I make perhaps six hundred gallons[16] of gas; for, when my reservoir is full, we are forced to burn away the overplus in waste, unless we have work to use it as it is made: but, in general, we go on making and using it, so that I cannot tell to fifty or a hundred gallons;--and, in fact, a great deal depends on the coals, some coals making much more than others. These twenty-five pounds of coal put into the retort, and say twenty-five pounds more to heat the retort, which is more than it does take one time with another, but I am willing to say the utmost, are worth four-pence per day. From this four-pence we burn eighteen or twenty lights during the winter season.” [16] A wine-gallon is equal to 231 cubic inches.