Among persons interesting themselves in the progress of British manufactures, it can scarce fail to be known, that Mr Neilson of Glasgow, manager of the Gas Works in that city, has taken out a patent for an important improvement in the working of such furnaces as, in the language of the patent, “are supplied with air by means of bellows, or other blowing apparatus.” In Scotland, Mr Neilson's invention has been extensively applied to the making of cast-iron, insomuch that there is only one Scotch iron-work where the invention is not in use, and in that work, apparatus is under construction to put the invention into operation.