ting the spokes or arms. If the spokes are four in number, the process is very simple. We take two pieces of timber long enough to reach across the wheel, and plane them to the required thickness of arm, and have them sufficiently wide to shape the hollows about the hub and towards the rim. Then we make a mark with a pencil on one side of each, which we call the face. We then set a gage to half the thickness of the spoke, and with it mark lines on both edges of each piece, always gaging from the face side. We meet at the center of the length, cut a recess out of each sufficiently wide and deep to admit the other, so that the pieces, when put together, form a cross, which we let into the wheel and fix temporarily with brads. We now place the work in the lathe, and start the lathe so as to find the center of the wheel, from which center we draw out the arms, and then turn out the recess to receive the hub. We mark the arms to their respective places in the rim, so as to be able to correctly replace them, and then we take them out of the rim, and shape them to their proper conformation. This being done, we glue them to their places in the rim. In the case of six arms being required, all these operations are similar, with the exception that there are three pieces to be framed together for the spokes instead of two; and we proceed in the following manner: We divide the thickness of any one piece into three equal parts, and mark lines to these equal divisions on the edges of all the pieces. These gage lines need not extend the full length of the pieces, but only for some distance, about the center of the length, where it is expected the recess will be cut out. We next gage center lines on the flat sides, and find the centers of the lengta approximately. A, B, and C, in Fig. 134, represent our three pieces, which, when put together, are to form the six arms. Setting the compasses to a radius of one half the width of the pieces, we mark (from the centers already found) circles on one side of the pieces A and C, and also on both sides of B. We next set a bevel square to an angle of 60°; and with this, set to touch the edge of the circle, we draw, on A and C, tangents crossing each other; and on the piece B, four such tangents, two on each side, must be marked. The piece A must now be recessed between one pair of tangents to a depth of two thirds of its thickness, and between the other pair to a depth of one third. B must be recessed on each side to a depth of one third its thickness; while on the piece C, the whole of the space included between the tangents must be cut away to the depth of two thirds. The recesses must be cut true to the lines, and level, a rabbet plane being useful for the purpose, unless the work is small; and if the job has been carefully executed, the pieces will fit right together, and may be glued without further labor. For an odd number of arms, such as 3, 5, or 7, the method of putting together is different, and is not so strong as the -------- foregoing. It is as follows: Upon a flat piece of board, fasten a piece of paper, and describe upon the latter a circle; then divide the circumference of the latter into as many equal parts as it is required to have arms, and draw lines from this center of the circle to the circumferential points of division, as shown in Fig. 135. Then bevel the Fig.135 ends of the pieces equally on each side, so that each shall exactly cover its own division of the circle; and as each is fitted, fasten it temporarily down, and when all are fitted, verify the work as follows: Observe if the pieces are equidistant from one another, at an equal distance from the center of the circle, and at or near the extremities, when any error will be easily detected and rectified. Then glue the pointed ends all together, fastening each piece temporarily to the board, as before, and set the whole away, until it is quite dry, when the piece may be taken from the board, and the required form given to the arms, ready for finally fixing to the rim of the pattern. In almost all cases it is necessary that wheels of this kind be provided with hubs; and by the attachment of the latter, the joints of the spokes at the center, when made as shown in Fig. 135, are very much strengthened. But in the rare event of having to put together such a combination of arms without hubs, it will be advisable to turn out a recess at the center, making it as large as practicable, and fitting into it a disk of hard wood. Before cutting out the spaces in the rim to receive the extre mities of the arms, it is necessary to turn out that part of the rim to the finished size, as it will be inaccessible to the turning tool, when the arms are glued in. The arms being fitted to their places, and made fast to the rim, we proceed to turn all that can be got at that is to say, the exterior diameter of the body of the half of the half-pattern, and also the flange. It is needless to add that each half of the pattern must be similarly treated. The work is now to be reversed on the chuck, and the inside turned out, together with a recess at the center, to receive the hub. To maintain the two halves of the pattern in coincidence, two, and sometimes three or more, pegs are inserted in the arms of one half, which pegs fit into holes bored to correspond in the arms of the other half of the pattern. In some cases, the flanges of the pattern are required to be so thin as not to admit of two layers or courses of segments in their composition, in which eventespecially if the flanges extend far from the body of the pattern-it is well to strengthen the joints of the segments. Perhaps the neatest way of accomplishing this, is to make a saw cut in the ends of each segment, and, at the time of gluing, to insert a tongue or thin strip of wood, nicely filling the saw cut, the grain of the tongue being at right angles to the line of the joint of the segments. Care should, however, be taken to have the saw cut in each at a similar distance from the face of the segment. It will be perceived that the flanges might be omitted without making any difference in the method of construction; nor does the method to be pursued vary to any great extent for all kinds of rope or chain pulleys. CHAPTER VIII. PIPE BENDS, AND LAGGING. Our next example will be a pipe bend, such as is shown in section in Fig. 136. It will be seen upon examination that the bend proper is included in that portion contained within the dotted lines, C C and D D, which meet at the center from which the arcs, forming the bend, are struck. Those parts exterior to the dotted lines are made separately from the bend proper, and are subjects in plain turning, similar to those already treated upon. It will be noted, however, that in this kind of pattern the core is not so well supported as in our previous examples; and it has, there |