The Tripods, figs. 747. 748, are adaptations of Pompeian pedestals. The first, a Table lamp stand, fourteen inches high, has three supports braced together by square diagonal pieces connected to central rings; one side and two shafts only being shown to avoid confusion. The shafts terminating in pins, pass at an angle through separate capitals and bases, by one of the methods figs. 688. 690, into apertures bored in the surfaces of horizontal quadrants, cut from circular pieces, turned to the required profile; the flat sides of the latter being enriched by inserted ornaments, formed by a series of turned fillets. The upper and under surfaces of the quadrants are connected to the vase above and the feet below by vertical pins turned in the solid upon interposed collars. The feet are cut from a ring turned to the profile, the flat surfaces of their sides receiving similar ornaments to those above them; the foundation plate being of the curved triform plan already described. The diagonal bracing, principally required to give character to the design, is formed of pieces of square section, the ends of which are turned with cylindrical mouldings and pins, inserted in appropriate apertures made in the quadrants and in their central connecting rings.
The second Tripod to support a lamp, statuette, or flower vase, stands on the floor and is forty-eight inches high. The long uprights again terminate in pins, which pass into the crescents above and into the quadrants below; both formed from rings turned of square section. Turned from single pieces the shafts would probably require the lengthening bearers, fig. 185, but they may also be each made in two lengths joined in the central ornament; one length having an aperture in the end, turned with the piece supported in the boring collar, and the other, provided with a corresponding pin; the method that was adopted in constructing this specimen. The shafts are connected and strengthened towards their lower ends by a central disc, to which they are attached by screwed pins with ornamental heads, passing transversely through them; the upper and lower surfaces of the disc carrying a vase and a pendant ornament. The lifting blocks Figs. 182, 183, would be required to turn the circular plate, fourteen inches diameter, connecting the lower ends of the feet. The vase and its pendant at the summit, is formed of three or more pieces as may be convenient to the material; the pendant being attached by horizontal pins, passing only partially through the three crescents and therefore concealed. The portions of square rings forming the latter, have the two holes for these and the pins of the shafts, bored in exactly similar positions in all three, and their radial surfaces are also pierced with apertures to receive the terminal ornaments.
In concluding the description of the specimens of plain turning contained in the foregoing chapters, it should be noticed that in copying from designs or existing works, it will frequently happen that the reproduction has to be executed on an increased or diminished scale, in order that the copy may agree with the height or diameter of some particular piece of material to be employed. The exact and relative proportions of all parts of the design then requisite, may be readily ascertained by mechanical assistance; the most familiar being that afforded by proportional compasses.
By means of its sliding center the one end of this instrument may be arranged to measure, say, one and a quarter, two and a half, three times, or other proportions of that shown by its opposite points; and in this manner the shorter ends of the compasses being adjusted to the height of any of the foregoing figures, while the longer agree with that of the piece of material selected, all the measures then taken on the original with the former, are equally increased by the latter, and the form may be delineated in accordance upon paper, before commencing the work. Proportional callipers which resemble the callipers, fig. 342, but have the legs terminating in points, and the center moving and fixing to different positions along them, are still more convenient for the purpose. The pointed ends are used to measure the design, while with the calliper bows, the increased measures can be directly applied to the length or diameter of the work in progress.