tion by means of ropes and pulleys, fixed to beams above. While the metal is melting, the surface of the mould, or table, is prepared by covering it with a stratum of dry and clean sand, regularly smoothed over with a kind of rake, called a strike, which consists of a board about 5 inches broad, and rather longer than the inside of the mould, so that its ends, which are notched about two inches deep, may ride upon the shafts. This being passed down the whole length of the table, reduces the sand to an uniform surface. The pan is now brought to the head of the table, close to the copper, its sides having previously been guarded by a coat of moistened sand, to prevent its firing from the heat of the metal, which is now put in by ladles from the copper..

These pans, or boxes, it must be observed, are made to contain the quantity of melted lead which is required to cast a whole sheet at one time; and the slit in the bottom is so adjusted as to let out, during its progress along the table, just as much as will completely cover it of the thickness and weight per foot required. Every thing being thus prepared, the slit is opened, and the box moved along the table, dispensing its contents from the top to the bottom, and leaving in its progress a sheet of lead of the desired thickness. When cool, the sheet is rolled up and removed from the table, and other sheets are cast, till all the metal in the copper is exhausted. The sheets thus formed are then rolled up and kept for use.

In some places, instead of having a square box upon wheels, with a slit in the bottom, the pan consists of a kind of trough, being composed of two planks nailed together at right angles, with two triangular pieces fitted in between them, at their ends. The length of this pan, as well as that of the box, is equal to the whole breadth of the mould. It is placed with its bottom on a bench at the head of the table leaning with one side against it: to the opposite side is fixed a handle, by which it may be lifted up in order to pour out the liquid metal. On the side of the pan next the mould are two iron hooks, to hold it to the table, and prevent it from slipping while the metal is being poured into the

mould.

The mould, as well as the pan, is spread over, about two inches thick, with sand, sifted and moistened, and rendered perfectly level by moving over it the strike, and smoothing it down with a plane of polished brass, about a quarter of an inch thick, and nine inches square, turned up on the edges. Before they proceed to casting the lead, the strike is made

ready by tacking two pieces of old hat on the notches, or by covering the notches with leather cases, so as to raise the under side of the strike, about an eighth of an inch, or more, above the sand, according to the proposed thickness of the sheet. The face or under side of the strike is then smeared with tallow, and laid across the breadth of the mould, with its ends resting on the shafts. The melted lead is then put into the pan with ladles; and, when a sufficient quantity has been put in, the scum is swept off with a piece of board, and suffered to settle on the coat of sand, to prevent its falling into the mould, when the metal is poured out. It generally happens, that the lead, when first taken from the copper, is too hot for casting; it is therefore suffered to cool in the pan, till it begins to stand with a shel or wall on the sand with which the pan is lined. Two men then take the pan by the handle, or one of them takes it by means of a bar and chain fixed to a beam in the ceiling, and turn it down, so that the metal runs into the mould: while another man stands ready with the strike, and, as soon as all the metal is poured in sweeps it forward and draws the residue into a trough at the bottom, which has been prepa red to receive it. The sheet is then rolled up, as before.

In this mode of operation, the table inclines in its length about an inch, or an inch and a half, in the length of sixteen or seventeen feet, or niore, according to the required thickness of the sheets; the thinner the sheet the greater the declivity; and vice versa. The lower end of the mould is also left open, to admit of the superfluous metal being thrown off.

When a cistern is to be cast, the size of the four sides is measured out; and the dimensions of the front having been taken, slips of wood, on which the mouldings are carved, are pressed upon the sand. Figures of birds, beasts, &c. are likewise stamped in the internal area, by means of leaden moulds. If any part of the sand has been disturbed in doing this, it is made smooth, and the process of casting goes on as for plain sheets; except that, instead of rolling up the lead when cast, it is bent into four sides, so that the two ends, when they are soldered together, may be joined at the back; the bottom is afterwards soldered up.

The lead which lines the Chinese tea-boxes is reduced to a thinness which our plumbers cannot, it is said, approach. The following account of the process was communicated by an intelligent East-Indian, in a letter which ap peared in the Gentleman's Magazine. "The caster sits by

a pot, containing the melted metal, and has two large stones, the lower one fixed and the upper one movable, having their surfaces of contact ground to each other, directly before him. He raises the upper stone by pressing his foot upon its side, and with an iron ladle pours into the opening a sufficient quantity of the fluid metal. He then lets fall the upper stone, and thus forms the lead into an extremely thin and irregular plate, which is afterwards cut into its required form."

Cast sheet lead, used for architectural purposes, is techni cally divided into 5lb. 54lb. 6lb. 64lb. 71b. 74lb. 8lb. and 84lb.; by which is understood, that every superficial foot is to contain those respective weights, according to the price agreed upon.

The milled lead used by plumbers is very thin, seldom containing more than 5lb. to the foot. It is by no means adapted to gutters or terraces, nor, indeed, to any part of a building that is much exposed either to great wear or to the effects of the sun's rays: in the former case, it soon wears away; in the latter, it expands and cracks. It is laminated in sheets of about the same size as those of cast lead, by means of a roller, or flatting-mill.

Lead-pipes, besides the various ways of manufacture described in page 362, are sometimes made of sheet lead, by beating it on round wooden cylinders of the length and dimensions required, and then soldering up the edges.

Solder is used to secure the joints of work in lead, which by other means would be impossible. It should be easier of fusion than the metal intended to be soldered, and should be as nearly as possible of the same colour. The plumber therefore uses, what is technically called, soft solder, which is a compound of equal parts of tin and lead, melted together and run in to moulds. In this state it is sold by the manufacturer by the pound.

In the operation of soldering, the surfaces or edges intended to be united are scraped very clean, and brought close up to each other, in which state they are held by an assistant, while the plumber applies a little resin on the joints, in order to prevent the oxidation of the metal. The heated solder is then brought in a ladle and poured on the joint; after which it is smoothed and finished by rubbing it about with a red-hot soldering iron, and when completed is made sn.ooth by filing.

In the covering of roofs or terraces with lead, (the sheets) never exceeding six feet in breadth,) it becomes necessary in

large surfaces, to have joints; which are managed several ways, but in all, the chief object is to have them watertight. The best plan of effecting this, is to form laps or roll joints, which is done by having a roll, or strip of wood, about two inches square, but rounded on its upper side, nailed under the joints of the sheets, where the edges lap over each other; one of these edges is to be dressed up over the roll on the inside, and the other is to be dressed over them both on the outside, by which means the water is prevented from penetrating. No other fastening is requisite than what is required from the hammering of the sheets together down upon the flat; nor should any other be resorted to, when sheet lead is exposed to the vicissitudes of the weather; because it expands and shrinks, which, if prevented by too much fastening, would cause it to crack and become useless. It sometimes, however, occurs, that rolls cannot be used, and then the method of joining by seams is resorted to. This consists in simply bending the approxi inate edges of the lead up and over each other, and then dressing them down close to the flat, throughout their length. But this is not equal to the roll, either for neatness or security.

Lead flats and gutters should always be laid with a current, to keep them dry. About a quarter of an inch to the foot run is a sufficient inclination.

In laying gutters, &c. pieces of milled-lead, called flashings, about eight or nine inches wide, are fixed in the walls all round the edges of the sheet-lead, with which the flat is covered, and are suffered to hang down over them, so as to prevent the passage of rain through the interstice between the raised edge and the wall. If the walls have been previously built, the mortar is raked out of the joint of the bricks next above the edge of the sheet, and the flushings are not only inserted into the crack at the upper sides, but their lower edges are likewise dressed over those of the lead in the flat, or gutter. When neither of these modes can be resorted to, the flushings are fastened by wall-hooks, and their lower edges dressed down as before.

Drips in flats, or gutters, are formed by raising one part above another, and dressing the lead, as already described, for covering the rolls. They are resorted to when the gutter or flat, exceeds the length of the sheet; or sometimes for convenience. They are also an useful expedient to avoid soldering the joints.

Sheet lead is also used in the lining of reservoirs, which

are made either of wood or masonry. As these conveniences are seldom in places subject to material change of temperature, recourse may be had to the soldering, without fear of its damaging the work, by promoting a disposition

to crack.

The pumps which come under the province of the plumber, are confined generally to two or three kinds, used for domestic purposes, of which the suction and lifting pumps are the chief: these, as well as water-closets, are manufactured by a particular set of workmen, and sold to the plumber, who furnishes the lead pipes, and fixes them in their places.

Plumber's work is generally estimated by the pound, or hundred weight; but the weight may be discovered by measurement, in the following manner sheet-lead used in roofing and guttering is commonly between seven and twelve pounds to the square foot; but the following table exhibits the particular weight of a square foot for each of the several thicknesses.

In this table the thickness is set down in tenths and hundredths, &c. of an inch; and the annexed corresponding numbers are the weights in avoirdupois pounds, and thousandth parts of a pound; so that the weight of a square foot of 1-10th of an inch thick, 10-100ths, is 5 lbs. and 899 thousandth parts of a pound; and the weight of a square foot 1-9th of an inch in thickness, is 6 pounds and 554 thousandths of a pound. Leaden pipe of an inch bore, is commonly 13 or 14 lbs. to the yard in length.

GLAZING.

The business of this class of artificers consists in putting glass into sashes and casements. Glazier's work may be classed under three distinct heads, sash work, lead-work, and fret-work.