lines of all such parts as are immediately transferable by the help of the square and compasses, from one figure to the other. The outline e k and fl are arcs, whose centres lie in ef produced, and pass through the points e, k and f,l. To find the projection of this arc upon the plan (fig. 2), draw through any points m and n, taken at pleasure upon the arc e k (fig. 3), the horizontals mm, n n, and through m and n (fig. 1) draw m m and n n parallel to CD, then set off the distances o m and p n (fig. 3) to the corresponding points on the lower side of centre line M N (fig. 2): thus the curve e m n k will be determined. By a similar method the curve cm n' will be obtained, as also the projections of all such arcs as are denoted by rq (fig. 3).

To draw on fig. 3 the s t h (fig. 2), which is the line of penetration of two cylinders, a similar construction to the preceding may be adopted. But to avoid drawing too many lines on the figures, this projection is constructed (see fig. 5) on another part of the sheet, in which s t h' represent the plan of the curve s t h (fig. 2), and h v2 t the elevation, as at fig. 1. Divide hv2 t into any number of equal parts; let fall perpendiculars h h' v2 v'. . . from the points of division, and horizontal and parallel lines hh, vv...; lay off on each side from the half chords made on the semicircle, and we have the curve h v tv 8, which may easily be transferred to its position in fig. 3.

It will be observed, that one side of the elevation (fig. 1) is represented as broken; this is often done in drawing, when the sides are uniform, and economy of space on the paper is required.

Suspended bearings or hangers for horizontal shafts are divided into two general classes-side hangers (figs. 240, 241), and sprawl hangers

(plate XI., fig. 1); the figures will sufficiently explain the distinction. The side hanger is the more convenient when it is required to remove the shaft, and when the strain is in one direction, against the upright part; they are generally used for the smaller shafts, but sprawl hangers affording a more firm support in both directions, are used as supports for all the heavier shafts. Hangers are bolted to the floor timbers, or to strips placed to sustain them, the centres of the boxes being placed accurately in line, both horizontally and laterally.

Plate XI.-Fig. 1 represents the elevation of a sprawl hanger; fig. 2, the plan looking from above, with cover of box off; fig. 3, a section on the line A B, fig. 1.

Fig. 4 represents the elevation of a bracket, or the support of a shaft bolted to an upright; the box is movable, and is adjusted laterally by the set-screws. Fig. 5 is a front elevation of the back plate cast on the post; it will be seen that the holes are oblong, to admit of the vertical adjustment of the bracket. Fig. 6 is a side elevation of the box; fig. 7, a section lengthways, showing aperture for grease, and the points which retain the babbit-metal lining in its place; fig. 8 is a plan of the bottom half of the box; fig. 9, plan of the top.

Fig. 242 represents different views of what may be called a yokehanger. Fig. 1 is a front and fig. 2 a side elevation; fig. 3 a plan of the hanger, looking up; and fig. 4 a plan of the yoke, looking down upon it. A is the plate which is fastened to the beam, E is the yoke, and B the stem of the yoke, cut with a thread so as to admit of a vertical adjustment; the box D of the shaft C is supported by two pointed set-screws passing through the jaws of the yoke; this affords a very flexible bearing, and a chance for lateral adjustment.

Couplings are the connections of shafts, and are varied in their construction and proportions often according to the mere whim of the mechanic making them.

The Face Coupling (fig. 242) is the one in most general use for the connecting of wrought iron shafts; it consists of two plates or discs with long strong hubs, through the centre of which holes are accurately drilled to fit the shaft; one-half is now drawn on to the shaft, and tightly keyed; the plates are faced square with the shaft, and the two faces are brought together by bolts. The number and size of the bolts depend upon the size of the shaft, never less than 4 for shafts less than 3 inches diameter, and more as the diameter increases; the size of the bolts varies from to 1 in. in diameter. The figure shows a usual proportion of parts for shafts of from 2 to 5 inches diameter; for larger than these, the proportion of the diameter of the disc to that of the shaft is too large.