known as open well or open newel stairs. or joists of floors and landings. Winding stairs have a separate bearer under each step extending from wall to newel. Cross bearers or carriages are also employed as with straight flights. Handrailing is supported by newels and balusters, or in geometrical stairs by balusters alone. It follows the inclination of the stairs, rising more rapidly over the narrow ends of winders than over fullwidth straight ones. It should be several inches higher on the level than it is when inclined. In stairs with newels it is usually in straight lengths, sometimes curved at the ends to raise or lower its height as it reaches a level. In geometrical stairs its curves are complex, as it is re The form of the landings Fig. 37.-Geometric Stairs. and presence or absence of winding stairs at the turns does not affect this distinguishing feature of the two varieties. In both cases, posts, or newels, as they are called, occur at each change of direction in the stairs and handrail. The other type, shown in Fig. 37, are called geometrical stairs, and in these there are no newel posts, but the handrail continues without interruption and without angular turns. These stairs may be of almost any form in plan, but there is always a well. In all types the individual steps are built into inclined timbers called strings. Usually they are housed about half an inch into the string which goes against the wall, and the other string is notched to the shape so that the treads and risers which form the steps can be fitted over it. Details are shown in Fig. 38, in which a is the wall string, and в the cut, or open string. Other timbers, called carriages, are often fitted in intermediate positions running parallel with the strings. These give intermediate support to the steps and are useful for attaching laths and plaster to. Straight flights of stairs are generally glued up in the workshop ready to go in place. Other portions generally have to be put together on the spot. Landings are supported by joists from the walls similarly to floors. Strings are either tenoned into newels, or notched and bolted to trimmers quired to twist to keep its cross section normal with the stairs while rising, and simultaneously following lateral bends. It is jointed in lengths with plain butt joints, dowelled and held together by handrail bolts. Fig. 38.-Details of Stairs. Joint Board.-See Bottom Board. Joist, H-Section, or H-Girder, IBeam, or Beam, or Rolled Joist.-One of the most valuable forms of beams rolled. They range from about 3 in. in depth, by 1 in. breadth of flange, to 24 in. by 7 in. The inner edges of the flanges have from 5° to 8° of angle, or draft. Figs. 39 and 40 illustrate the roughing and finishing rolls for joists of 6-in. Fig. 39.-Grooved Grain Roughing Rolls, 32-in. Centres, by 6 ft. long, for producing Joists 6 in. by 3 in. by 3 in. (Thos. Perry & Son, Ltd.) Fig. 40.-Grooved Grain Finishing Rolls, for Joists 6 in. by 3 in. by 3 in. (Thos. Perry & Son, Ltd.) Fig. 41.-Joy's Valve Gear. Lancashire and Yorkshire Railway (G. Hughes, Esq., Locomotive Superintendent). depth, and 3-in. flanges. The gradual reduction is apparent. Briefly it may be stated thus:A cogged bloom or slab after some preliminary reduction is entered into the closed passes of the roughing rolls, Fig. 39-the first on the right of the figure. The first pass produces a Gothic furrow on each side, the next a nearly semicircular one, after which the shapes approximate to the H section. In each successive pass the furrows are deepened and widened, and the draft becomes lessened. The vertical dimensions of flanges and web lessen, the width or depth of the section increases, and the radii in the corners are reduced, the joist being finished in the left-hand pass in Fig. 40. only supported at intervals of 8 ft. or 10 ft., they may be 5 in. deep. Generally they are 2 in. thick in either case. Floor joists are never less than 2 in. thick, and seldom less than 9 in. deep. Both floor and ceiling joists are generally spaced about 12 in. apart. The binders of a floor are sometimes called binding joists. Bridging joists is another term for floor joists. Joule's Law.-Expresses the fact that the quantity of heat produced by friction, if preserved and accurately measured, is always proportional to the quantity of work expended. Experiments were made on the energy of a descending weight rotating paddles in a liquid Joists-in Wood.-The term is applied to the timbers on which flooring boards are laid, and to those put up specially for attaching ceiling laths to. The former are called floor joists, and the latter ceiling joists. Timbers known as trimming joists are also frequently required in floors, and are of larger section than the ordinary floor joists. The latter measure in section about 2 in. by 3 in., and should not span more than 8 ft. to 12 ft. without support. Ceiling joists, having only the ceiling to support, are of less depth. When attached directly to the under edges of the floor joists, 3 in. is usually sufficient. When attached to binders, and consequently and so raising its temperature. They established the exact relationship between mechanical energy and heat. Joule stated it as the number of units of work in kilogrammetres necessary to raise by 1° Cent. the temperature of 1 kilogram of water. This was 424, the heat unit expressed in metric terms. Expressed in English terms this is equivalent to saying that to raise a pound of water say from 39° Fahr. to 40° Fahr., is equivalent to 772 ft. lb. of work. This is the mechanical equivalent of heat, termed a Joule. Joy's Valve Gear.-A valve gear named after its inventor, Mr David Joy, and designed to avoid the use of eccentrics. It is used largely on locomotive engines, notably on those of the Lancashire and Yorkshire Railway, and on some marine engines. The motion is derived from the connecting rod. The amount of opening of the ports is equal at both ends of the valve, and early cut off can be obtained without excessive amounts of lead and early exhausts. It saves space, so that longer crank pins and journals can be used. A working drawing of Joy's gear as used on the engines of the Lancashire and Yorkshire Railway, kindly supplied by the chief mechanical engineer, G. Hughes, Esq., is shown in Fig. 41, and a skeleton diagram in Fig. 42 to serve as a key to the former. The following is a condensed summary of Mr Joy's instructions for laying out the gear, Fig. 42. Draw the centre line of the cylinder A B, and that of the valve spindle CD; the latter must be in the plane of the vibration of the connecting rod. Draw the circle A E of the crank pin, and the centre lines of the connecting rod FG, HG for the upper and lower positions respectively, with the piston at mid stroke. Take a point J on the centre line of the connecting rod, where its vibration between K and L is equal to about double the length of the full stroke of the valve. It is better to allow rather more than less, in order to avoid too great an angle of the slide link when angled for full forward or backward gear. Through the point J draw the line KL perpendicular to A B. From J mark off JM, JN, being the extreme positions of the point J on the connecting rod for forward and backward stroke. From м and N draw lines to a point o on the vertical line, so far down that the angle between them shall not exceed 90°, and better if less. These points MNO will represent the centres of the first correcting link A (Fig. 41), pinned to the connecting rod. The point or pivot o, which will rise and fall with the vibration of the connecting rod, is to be controlled as nearly as possible on the vertical line by a link P-the anchor link B in Fig. 41-pinned either forward near the cylinder, as at Q, or in the other direction. Next, on the centre line of the valve spindle c D, on each side of the centre, set off RS, RT, equal to the lap and lead for the front and back end of the cylinder respectively. Then, assuming the piston to be at the front of the cylinder, and the centres of the connecting rod to be at E E',-E being the crank pin,-the point to take the motion from will be at N, and the link pinned to the connecting rod for transmitting motion to the valve will be connected at No (the link a in Fig. 41). From a point on this link which has to be assumed first, say at a, which will be about one-third more than the half vibration of the connecting rod, that is, J to K, draw the centre line of the lever U (D in Fig. 41) actuating the valve, that is joining a and s. The point where this point crosses the vertical will be the fulcrum of the lever, and the centre of oscillation of the curved links (c in Fig. 41) in which the blocks which carry the centres of the lever slide. Both centres must be concentric at each end of the stroke. The function of the link N o, and the attachment of the valve lever to it at a, is to eliminate the error in vibration of the lever centre b, which would otherwise arise from the arc passed through by the lower end of the lever. To test if the assumed point b be the correct one, mark off the distances bc, bd (see the diagram, Fig. 42) below and above b on the vertical line, so that cd is equal to the vibration of the connecting rod on the vertical line, or K L. Then set off the distance Na to Ke, and to Lf. Then if the length ab is applied to cd (measuring from c) and to fe (measuring from ƒ), and the point b falls below cd in each case, it will be necessary to take a point on the lever No higher than a. Or if, on the other hand, b falls above cd, then a point must be taken on No lower than a. The point b now represents the centre of oscillation for the links (c in Fig. 41 and the fulcrum of the lever D in that figure), and these, as already mentioned, must coincide when the piston is at each end of the stroke, the lead being then fixed, and the links can be pulled over from forward to backward, or to any point of expansion without altering the lead. This is a test always applied when setting the valves. The point R will be the point of attachment |