The solder is melted in an iron ladle, on a rude temporary fire-place, built as near the spot where the solder is wanted as possible. The plumber having turned back the edge of the upper sheet at the joint, an assistant carefully pours the solder on the lower edge. The workman then spreads it evenly along the joint, by means of _soldering irons_, which are irregularly-shaped iron bars, swelling at their ends into rounded forms of different sizes and shapes, according to the particular purpose for which they are intended. These irons are used in a red-hot state in order to keep the solder melted. As soon as the workman has spread the solder, he presses and hammers down the upper edge upon the lower, and spreads the solder forced out of the joint, along the seam. The outermost edge of the lead covering is nailed down to the boarding or cistern-frame by nails, with their heads leaded over to prevent the corrosion of the metal, by the chemical or _voltaic_ action that takes place when two metals in contact are exposed to moisture. The situation of the soldered joints depends on the size and form of the surface to be covered over; and a good workman considers well how he can cut out the lead so as to have the fewest joints, and these in the most favourable situations. If he has to line a cistern, he will cover the bottom in one piece, cutting the lead large enough to admit of its turning up for an inch or two at two of the sides, the joint consequently being made at these angles. When a large roof, like that of a church, is covered with lead, this is laid on in parallel bands as wide as the sheet will admit of, the edge of one sheet being turned over a wooden roller or fillet, nailed down on the boarding to receive it, while the edge of the next sheet is turned over the former lead again; the double thickness being well _flogged_ down to render the joint water-tight: and in this case no solder is used. The edges of lead gutters that turn up against the inside of the parapet are either laid as flat against the brick-work as possible, and secured so by iron _holdfasts_, so as to prevent rain from getting in; or to effect the same object, they are in all the better kind of buildings, turned into a joint, in the brick-work, between two courses.