communicating with the chimney. The retorts are charged every six hours. Formerly, for cooling the retort lids, a pulpy mass of lime and mud of the consistence of mortar was used under the cognomen of "blue billy." This has been superseded by Morton's Patent Air-tight Lid, and Holman's Patent Lever. The two mechanical contrivances combined for this purpose are most efficient, and when financially considered must be a great saving to the Company. In the new house there are seven retorts in a bed; these, when heated sufficiently, are simultaneously charged at each end with two scoopfuls of bituminous coal; the upper retorts, on account of their retaining more heat, are charged with three scoops--each scoop contains 1 cwt. 2 qrs. of coal As soon as the lids are closed with the patent lever and cross-bar the process of gas distillation commences. In house No. 7 there are 392 mouths--total number of mouths in all the retort houses 1,793. As clay retorts when heated at first have a tendency to crack, it is necessary that the process of heating should be slow, also to get them up to their proper heat a similar caution is requisite when cooling. Apart from the manufacture of gas, in order to attend to the furnaces with the view of keeping up the heat of retorts, a certain amount of Sunday labour is involved, but it is gratifying to state that at these works labour on the Lord's day is reduced to its lowest minimum. Among several annoyances in the manufacture of gas is the choking or stoppage of ascension pipes; the person whose employment it is to look after, and if possible prevent this, is called by his fellow-workmen "the pipe jumper." Pipes connected with the mouthpieces called the ascension pipes conduct the gas to the hydraulic main, this is a large pipe at the back of the ascension pipes partly filled with water, when the works are started into which the ends of the pipes from the retorts are made to dip, and by this means forms a seal by which the gas is prevented from finding its way back either by those retorts which the workmen may be re-charging or to other parts of the bench that for the time may be out of action. The hydraulic main and its supports are very strong in order to stand the alternate and unequal heating and cooling of the benches, and the enormous strain occasioned by the large extent of pipage. Wrought iron is used in preference to cast-iron because of its lightness, strength and elasticity.