The invention by Mr. W. Sugg, in 1868, of the famous "London" Argand constitutes an important epoch in the history of gas lighting. Prior to that time, the construction of this class of burners had been carried out in a wholly empirical manner; and such improvements as had been effected must be looked upon as being rather the fortuitous issues of hap-hazard endeavours, than as resulting from the acquirement of clearer views as to the conditions to be complied with in order to ensure the successful operation of the burners. The invention of the "London" Argand was the first earnest attempt to abandon the former chance methods, and to proceed upon more scientific lines. Its construction shows that its inventor possessed a thorough acquaintance with the principles of combustion; while, in many particulars, it exhibits an intelligent discernment, and a successful application of the precise means required to attain a desired end. In this burner, the extreme importance of causing the gas to issue at a low pressure is for the first time clearly recognized; and the manner in which this object is so successfully attained is as simple as it is ingenious. At the entrance to the burner the gas is divided among three narrow tubes, the combined capacity of which is much smaller than that of the pipe supplying the burner. Through these tubes the gas is conducted into a concentric cylindrical chamber (forming the main body of the burner), where its rapid flow is checked; the current, or swirl, which it may have acquired, is subdued; and the gas comes to a state of comparative rest before it issues into the atmosphere and is consumed. The top rim of this concentric cylinder is pierced with 24 holes, the aggregate area of which is considerably greater than that of the three supply-tubes; thus ensuring that the gas shall be delivered at a much lower pressure than that at which it enters the burner. By dividing the gas into three streams, which enter the cylindrical chamber at equidistant points in its circumference, the supply is equally distributed throughout the entire ring of holes; and a flame of even and regular shape is the result.