Abbildungen der Seite
PDF

slates is called trimming them; but the head of the slate is never cut. In that part holes are pierced through the slates by which the nails pass to the boarding. The operations of the slater are of so simple a nature, that we do not further think it necessary to detain the reader on this section, which with that of Sect. VIII. Chap. II. in this Book affords all the information that can be required.

SECT. VII.
plumberty.

2212. The plumber has but few working tools, for the facility with which the metal in which he works is wrought does not render a variety necessary. The principal are — a heavy iron hammer, with a short but thick handle. Two or three different sized wooden mallets, and a dressing and flatting tool, which is made of beech wood, usually about 18 inches long and 2, inches square, planed smooth on one side, and rounded on the other or upper side. It is tapered and rounded at one of its ends for convenient grasping by the workman. Its use is to stretch and flatten the sheet lead, and dress it into the shape required for the various purposes whereto it is to be applied, by the use of its flat and round sides as wanted. The jack and trying planes, similar to those used by carpenters, for planing straight the edges of their sheet lead when a regular and correct line is requisite. They also use a line and roller called a chalk line, for lining out the lead into different widths. Their cutting tools are chisels and gouges, of different sizes, and cutting knives. The latter are for cutting the sheet lead into strips and pieces to the division marked by the chalk line. They use also files of different sizes for making cistern heads to pipes, for pumpwork, &c. For the purpose of soldering, they have a variety of different sized grozing irons, which are commonly about 12 inches long, tapered at both ends, the handle end being turned quite round to allow of its being held firmly in the hand whilst in use. The opposite end is spherical, or more usually spindle-shaped, and proportioned to the different situations for which they are required. The grozing iron is heated to redness when in use. The iron ladles are of three or four sizes, and used for the purpose of melting lead or solder. The plumber's measuring rule is 2 feet long, in three parts, each of 8 inches. Two of the legs are of box-wood, and the third of steel, which is attached to one of the box legs by a pivot whereon it turns, and shuts into the other legs in a groove. The steel leg is useful for passing into places which the plumber has to examine, into which anything thicker would not easily enter, and it is often used also for removing oxide or other extraneous matter from the surface of the heated metal. The plumber moreover is provided with centre bits of all sizes, and a stock to work them in, for perforating lead or wood where pipes are to be inserted, as well as with compasses, for striking out circular portions of lead. Scales and weights are also in constant requisition, as nothing done by the plumber is chargeable till the lead is weighed.

22 13. The method most commonly adopted in laying sheet lead for terraces or flats, is to place it on a surface as even as possible, either of boarding or plastering. If boards are employed, they should be sufficiently thick to prevent warping or twisting, which, if it occur soon, causes the lead to crack or to become unsightly. As sheets of lead are not more than about 6 feet in width, when the area to be covered with them is large, joints become necessary, which are contrived in various ways to prevent the wet from penetrating. To do this, the best method is that of forming rolls, which are pieces of wood about 2 inches square extending in the direction of the joint, planed and rounded on their upper side. These being fastened under the joints of the lead between the edges of the two sheets which meet together, one is dressed up over the roll on the inside, and the other over both of them on the outside, whereby all entry of the water is prevented. No fastening is required other than the adherence of the lead by close hammering together and down on the flat: indeed, any fastening would be injurious, as by it the lead would not have free play in its expansion and contraction from heat and cold. If rolls are not employed, which from their projection are in some cases found inconvenient, seams are substituted for them ; but they are by no means equal to the roll either for neatness or security. They are formed by merely bending up the two edges of the lead, and then over one another, and then dressing them down close to the flat thoughout their length. Though some solder the joints, it is a bad practice, and no good plumber will do it, for the same reason as that just given in respect of fastenings in flats. A leaden flat, as well as a gutter, should be laid with a fall to keep it dry. A quarter of an inch in a foot is sufficient inclination for lead, if the sheets be 20 feet long, so that in this case they will be 5 inches at one end higher than at the other. . This giving a current, as it is called, is usually provided for by the carpenter previous to laying the lead.

2214. Round the extreme edges of flats and gutters where lead is used, are fixed pieces

[merged small][ocr errors]

of milled lead which are called flashings. When the lead work is bounded by a wall of
brick or stone work, the flashings are passed on one edge into and between a joint of the
work, and the edges of the flat or gutter being bent up, the other edge of the flashing is
dressed over it. If there be no joint into which the flashing can be inserted, it is fastened
on that side with wall hooks. Drips in flats and gutters are used when the length of the
gutter or flat is greater than the length of the sheet of lead, or sometimes for convenience,
or to avoid joining lead by soldering it. They are formed by raising one part above
another, and dressing the lead round, as has been described for rolls.
2215. The pipes used for the purposes of building are proportioned to their uses. Those,
for instance, for carrying away the soil from a water closet, or the conveyance of water from
roofs and sinks, are of course of larger diameter than those called service pipes, which are
merely, as their name implies, for laying on water.

[blocks in formation]

2216. The work of the plumber is estimated by its weight and the time employed in fixing it. The weights and thicknesses of different sizes of sheet lead have been already given in Chap. II. Sect. VI. of this Book. 2217. The lead generally used in roofing and guttering is from 7 to 12 lbs. to the superficial foot, and great vigilance on the part of the architect is required, in these days of contracts, to see that his employer has the thickness, or, which is the same thing, the weight that has been contracted for. 2218. We do not think it necessary to describe at length the machinery of a water closet. Every one knows that the principle on which it is formed is that of a head of water in a cistern placed above it, which by means of a lever attached to a valve in the cistern allows a body of water to rush down and wash the basin, whose valve is opened for the discharge of the soil at the same moment that the water is let down from the cistern. Various instruments for this purpose have been contrived and patented, but we are not aware of any better than those which were made by the late Mr. Bramah, almost as soon as the subject formed a matter of inquiry. The reader will obtain by the inspection of one a far better notion than words or diagrams will convey. 2219. As it is a branch of the plumber's trade to find and fix the pumps for the supply of water to a dwelling, we think it right to furnish a description of the three sorts commonly used, which are the lifting, the common, and the force pump. 2220. Fig. 804, is a diagram of a lifting pump, in which ABCD is a short cylinder submerged in the well or other reservoir, whence the water is to be raised. In this cylinder a valve is placed at r, above which the pipe or tube CE is carried upwards as high as is requisite for the delivery of the water. In the cylinder AD a water-tight piston moves vertically, being worked by rod or framework as seen in the diagram. To this piston is fixed a valve at v opening upwards. On the descent of the piston the pressure against the water opens the valve p, and the cylinder between the two valves is filled with the water. When the piston is then raised, the water between the valves being pressed upwards against the valve r, opens it, and is driven into the tube CE, from which, on the renewed descent of the piston, its returnisintercepted by the valver. The water follows the piston in its ascent by the hydrostatic pressure of the water in the reservoir outside the cylinder; and on the next descent of the piston the water will again pass through the valve v, and will be driven through the valve a on its next ascent. It is manifest from inspection that the valve r relieves the valve v from the pressure of the column of water in the tube CE during the descent of the piston; for if the valve v were subject to that pressure during the descent of the piston, it could not be opened by the pressure of the water in the well, inasmuch as its level is necessarily below the level of the water in the pipe CE. The valve v prevents the return of the water through the piston during its ascent. In Fig. 804. raising the piston a force is required sufficient to support the entire column of water from the valve v to the surface of the water in the tube CE. To estimate this, we must take the weight of a column of water whose base is equal to the area of a section of the piston, P p 4

[graphic]

and whose height is equal to that of the surface of the water above the valve v in the tube CE, Hence, after each stroke of the pump, the pressure on the piston and the force necessary to raise it, will be increased by the weight of a column of water whose base is the horizontal section of the piston, and its height equal to the increase which the elevation of the column in CE receives from the water driven through the valve r. In the figure cq is the piston, the bottom of whose rod is at b ; m and n are rods which connect it with the upper part of the work, and WW is the level of the water in the well. 2221. The common, or as it is usually called, suction pump a (shown in fig. 805.), is nothing more than a large syringe con- ME – —is nected with a tube whose lower extremity is plunged in the well from which the water is to be raised. The tube is called a suction to pipe (SO), and its end in the well is represented by O, which, for the purpose of preventing the ascent of solid impurities, that might choke the pipe and impede its action, is pierced with holes like a strainer. At the upper end of this suction pipe is placed the valver opening upwards. At this place the tube is connected with another, BC, which acts as a great syringe, and in which works a piston having a valve at v, also opening upwards. The piston is worked alternately upwards and downwards in common pumps by a lever called the brake, but it may be worked in many ways. In the figure, W is the level of the water, CD the flange, where the lower valve is fixed, cd the piston, ab the piston rod, and MN the cistern into which the water is raised and delivered by its gravity at the nozzle of the pump e. At the commencement of the operation the water in the suction tube stands at the same height as the water in the well, being equally subject to the atmospheric pressure; but as soon as the syringe BC exhausts the air by the upward and downward action of the piston cd, the pressure of the air in SO being diminished and rendered less than that on the surface of the water in the well, will rise in SO by the atmospheric pressure; and as the air becomes more completely exhausted in the column of water in the tube SO below the valve ar, so will its pressure on the surface of the column be diminished, and whilst that diminution goes on, the height of the column will increase. If the air could be entirely withdrawn from the tube SO, and a Fig. 805. perfect vacuum created beneath the valve r, similar to that existing above the mercury in a barometer, then the atmospheric pressure, acting with undiminished effect on the surface of water in the well, would, in the tube SO, sustain a column of water equal to a column of mercury of the same base and of the same height as the mercury in the barometer. Now, the specific gravity of mercury being 134 times greater than that of water, a force capable of sustaining a column of mercury 30 inches high, would sustain a column of water equal to 30 inches x 13}=405 inches=338 feet. But an absolute vacuum is never formed, and, moreover, in this country, as the barometric column varies between 28 and 31 inches in height, the valve r should on no account be more than 28 feet above the level of the water in the well, taking into consideration all the attendant circumstances. This is the construction and principle upon which the common household pump is formed, and in it no other aid is derived from atmospheric pressure than what we have already stated; hence the pump requires as much force to work it as, in general terms, is equal to the weight of all the water in it at any time, the atmospheric pressure affording no aid to the workman. The cistern at the top is placed for the purpose of affording an unintermitted discharge of the water by holding more than the whole accumulation of water which is contrived to be greater than the spout or nozzle will discharge. 2222. The forcing pump, whose construction is shown in fig. 806., is a combination of the common suction and lifting pump. CEFD is a suction pipe descending into the well, and at its top is the valve V opening upwards. The pump barrel ABCD is furnished with a solid piston cd, whose rod is ab, without any valve. From the side of the barrel, just above the suction valve, a pipe proceeds, communicating with an upright cylinder GH, carried to such height as the water is intended to be raised. At the bottom of this cylinder is placed the valve V’ Fig. 806. opening upwards. At the commencement of working, the suction pipe CE and the chamber between the piston and valves are filled with air. When the piston descends to the valve V, the air enclosed in the latter chamber becomes condensed, and opening,

[ocr errors]
[ocr errors]
[graphic]
[graphic]
[graphic]
[graphic]
[graphic]
[graphic]

therefore, the valve V', a part of it escapes through it. On raising the piston the air below it becomes partially exhausted, and that in the suction pipe, opening the valve V, by its greater pressure, expands into the upper chamber. A part of this is expelled when the piston next descends, by means of the valve V’. This action is similar to that of an air pump or exhausting syringe. When by the repetition of this action the air is sufficiently exhausted, the atmospheric pressure upon the water in the well causes the water to rise therefrom through the suction pipe and the valve V, into the chamber between the piston and the valves. When the piston next descends it presses on the surface of the water, and the valve V opening upwards prevents the return of the water into the suction pipe, while the pressure of the piston being transmitted by the water to the valve V', opens it, and as the piston descends, the water passes into the force pipe GH. On the next ascent of the piston more water is allowed to pass through the valve V, and the next descent forces this water through the valve V into the force pipe. By repeating the action the quantity of water in the force pipe increases, receiving equal additions at each descent of the piston. It is obvious that the position of the force pipe is a matter of no moment; it may be perpendicular, oblique, or horizontal; for in each case the water will be propelled through it. When the piston is pressed downwards, and the valve V* is opened, it is necessary that the force working the piston should balance the weight of the column of water in the force pipe, for this weight is transmitted by the water between the piston and force pipe to the bottom of the piston; the height, therefore, of the column of water in the force pipe will measure the intensity of the pressure against the base of the piston when the valve V" is open. A column of water suspended 34 feet in height in the force pipe will press on the base of the piston with a force of about 15 pounds for each square inch; and the pressure at other heights will be proportional to this. Thus the force necessary to urge the piston downwards may always be calculated. The valve V* is closed in drawing up the piston, and it then relieves the piston from the weight of the incumbent column. If the valve V is opened, the piston is subject to the same pressure as in the suction pump, and this has already been seen to be equal to the weight of a column of water raised above the level of the water in the well. From this it follows, that when the height of the force pipe is equal to the length of the suction pipe, the piston will be pressed upwards and downwards with equal forces; but when the height of the force pipe is greater or less than the length of the suction pipe, the downward pressure must be greater or less, in the same proportion, than the force which draws the piston up. 2223. The supply of water by the force pipe through the valve V' is evidently intermitting, being suspended during the ascent of the piston; hence the flow from the point of dis. charge will be subject to the same intermission if means be not taken to counteract such effect. A cistern at the top of the force pipe, as already shown, for the suction pump, would answer the purpose; but it is found more convenient to use an apparatus called an air vessel (see fig. 807.), in which immediately above the valve V" a short tube communicates with a strong close vessel of sufficient capacity, through the top whereof the force pipe GH passes, and descends to near the bottom. When the pump is in action the water is forced into the vessel MN, and when its surface, as at ww, rises above the mouth H of the force pipe, the air in the vessel M N is confined above the water; and as the water is gradually forced in, the air, being compressed, acts with increased elastic force on the surface of the water. This pressure forces a column of water into the pipe HG, and maintains it at an elevation proportional to the elastic force of the condensed air. When the air in the vessel MN is reduced to half its original bulk it will act on the surface of the water ww with double the atmospheric pressure; meanwhile, the water in the force pipe being subject to merely once the atmospheric pressure, there is an unresisted force upwards equal to the atmospheric pressure which sustains the column of water in the tube, and a column 34 feet high will thus be sustained. If Fig. 807. the air is reduced to one third of its original bulk, the height of the column sustained will be 68 feet, and so on. If the force pipe were made to terminate in a ball pierced with small holes so as to form a jet d'eau, the elastic pressure of the air on the surface would cause the water to spout from the holes. 2224. In the formation of all pumps the parts should be nicely fitted, and as air-tight as possible, otherwise, in using them, much of the power employed will be lost. All expedients which tend to this great desideratum are of value; indeed any arrangement adapted to insure the perfect action of a pump is of the utmost importance for the comfort and convenience of small no less than large dwellings.

[graphic]

SECT. VIII.
Glazi NG.

2225. Glazing, or the business of the glazier, consists in fitting glass in sashes, frames, and casements, either in putty or lead. It may be classed under the heads of sashwork, leadwork, and fretwork. Glass, as a material, has been already described in Chap. II. Sect. II. of this Book. 2226. The tools necessary for sashwork are— a diamond, polished to a cutting point, and set in brass in an iron socket, to receive a wooden handle, by which it is held in a cutting direction. The top of the handle goes between the root of the forefinger and middle finger, and the under part between the point of the forefinger and thumb. In general, there is a notch on the side of the socket, which should be held next the lath. Some diamonds have more cuts than one. Plough diamonds have a square nut on the end of the socket next the glass, which, on running the nut square on the side of the lath, keeps it in the cutting direction. Glass benders have their plough diamonds without long handles, as they cannot make use of a lath in cutting, but direct them by the point of their middle finger. The ranging lath should be long enough to extend beyond the boundary of the table of glass. Ranging of glass is the cutting it in breadths, and is best done by one uninterrupted cut from one end to the other. A short lath is used for stripping the square to suit the rebate of the sash, as in ranging they are generally cut full. A square, for the more accurate cutting at the right angles from the range. The carpenter's chisel is used in paring away some of the rebate of the sash when the glass does not lie so flat as to allow a proper breadth for front putty. The glazing knife is used for laying in the putty on the rebates, for bedding in the glass, and finishing the front putty. A bradding hammer is made with a head in the form of a small parallelopiped, with a socket for the handle, using it at an obtuse angle from the middle of one of its sides. The square edges of the head drive the brads in a horizontal direction, and with this tool there is less liability to accident than with any other. Some use the basil of the chisel for the purpose. Brass points are considered the best for bradding; small cut brads are also used. All new work should be bradded, to prevent the glass being moved out of its bed. The duster is a large brush for brushing the putties, and taking the oil from the glass. The sash tool is used wet, for taking the oil from the inside after the back putties are cleared off. The hacking knife is for cleaning out the old putty from the rebates where squares are to be stopped in. The use of the glazier's rule needs no explanation: it is 2 feet long, doubling in four different pieces. 2227. Leadwork for lights is often used for inferior offices, and frequently in country buildings. Frames made with crossbars receive these lights, which are fastened with leaden bars, called saddle bars. Where springs are wanted, a casement is introduced of wood or iron. Sometimes a sliding frame is used, particularly for church windows. 2228. The tool called the glazier's vice is for preparing the leaden slips with grooves, &c., to fit them for the reception of glass. The German vices are esteemed the best, and turn out a variety of lead in different sizes. There are moulds belonging to these vices in which bars of lead are cast; in this form the mill receives them, and turns them out with two sides parallel to each other, and about 3 of an inch broad, and a partition connecting the two sides together, about of an inch wide, forming on each side a groove near by of an inch, and 6 feet long. The setting board is that on which the ridge of the light is worked, and divided into squares, and struck out with a chalk line, or drawn with a lath, which serve to guide the workman. One side and end is squared with a projecting bead or fillet. The latterkin is a piece of hard wood pointed, and so formed as to clear the groove of the lead, and widen it, for the more readily receiving the glass. The setting knife is a blade with a round end, loaded with lead at the bottom of the blade, and having a long square handle. The square end of the handle serves to force the squares home tight in the lead; being loaded with lead, it is of greater weight, and also cuts off the ends of the lead with greater ease, as in the course of working these lights the lead is always longer than is necessary till trimmed. 2229. The resin box contains powdered resin, which is put on all the joints previous to soldering. Clips are for holding the irons. . All the intersections are soldered on both sides except the outside joints of the outer side, that is, where they come to the outer edge. These lights should be cemented, which is done by thin paint being run along the lead bars and the chasm filled with dry whiting. After it has stood a short time a small quantity of dry red or white lead is dusted over it, which will enable it to resist, the weather well. Fretwork is the ornamental part of lead-light work, and consists in working ground or stained glass into different patterns and devices, as may be seen in the old stained glass windows. 2230. In London a large portion of the glazier's business consists in cleaning windows. 2231. The putty in which the glazier beds the glass is of four sorts. Soft putty, which is composed of flour, whiting, and raw linseed oil; hard putty, composed of whiting and

« ZurückWeiter »