The former is applied in the bowls of small plain turned vases and tazze, the substance of parts or the whole of their hollowed portions being reduced, until sufficiently attenuated to become transparent. Ivory, from its strength and tenacity, is the most appropriate material, while it possesses an incidental advantage from its structure, the different layers of which are very visible in these thin works. This elegant effect may be enhanced by selecting a piece of ivory from a tooth of nearly circular section and of coarse grain, and chucking this with the nerve precisely central; the entire thin surface then exhibits a delicate transparent pattern, composed of a numerous and regular series of eccentric rings or ovals of varying opacity.

The sections given to the vase are those of the hemisphere, the tulip, the oval divided upon its shorter, and the ellipse upon either diameter, all forms having their greatest internal width at the mouth. The piece is first turned nearly to its external and internal shape, the curvature of the latter is then completed and polished, after which the work is mounted on a solid wood arbor chuck, precisely fitting the internal form. The wood chuck having been reduced nearly to this, the entire surface of the hollow of the vase is moistened with some coloured mixture, such as powdered red chalk and oil, and the work is applied to the chuck to obtain its exact counterpart. It marks all parts of the chuck that require further reduction by the tool, and the work is continually re-applied in the same manner, until by alteration of the former, the two surfaces prove to be identical in curvature.

The whole surface of the chuck is then coated with lampblack mixed in water, to which size or a small quantity of melted glue has been added; and when this is dry, the chuck and work having been slightly warmed, the two are carefully cemented together with thin glue all over their respective surfaces. After an interval to allow the glue to thoroughly harden, the external central portion by which the bowl is attached to its stem, is turned to shape, partially pierced with a plain hole or cut with a screw and polished; subsequently to which, the thickness of the bowl is gradually reduced externally, with the ordinary hand turning tools. As it becomes sufficiently thin the blackened surface of the chuck shows through the ivory, the equality of the colour shown affording the guide for the further and parallel reduction of the work, which by careful management of the tools may be continued to great tenuity. The upper edge may be left of the same thinness as the rest of the bowl, or it may be strengthened by a small bead or moulding turned upon it, as with the piece below, prior to reducing the remainder to transparency. The finished form is then polished, and the work is separated from the chuck by immersing the two in a vessel of water, until the one can be removed from the other without difficulty.

Similar specimens may be constructed in wood, but the material presents difficulties without usually allowing such complete results. The chuck and the work having been carefully prepared, the former is covered with white chalk rubbed on dry, a small portion within the lip of the vase only being glued, this glued portion being cut off and left on the chuck to release the finished work. Although not so readily executed in wood, excellent specimens may be met with. One, a masterpiece of antique German turning, in the author's possession, is a truncated taper vase made in beechwood, the transparent cup measuring two inches in diameter by the same high, mounted in the solid, on a turned beechwood stem, ornamented by mouldings, the milling tool and incised work. The bowl contains fifty similar cups loose one within the other, the smallest the size of a thimble. All these are left from the tool, semi-transparent, parallel in thickness, perfectly smooth within and without and very pliable, being only the substance of a thin wood shaving.

Additional elegance may be given to the foregoing works by mounting the transparent bowls upon delicate parallel shafts, some three to six inches high, terminating above and below in small spreading mouldings to break their junction with the vase and the foot. In ivory, such stems may be readily reduced to one sixteenth of an inch or less in diameter, and they are mentioned, as being among the more delicate specimens of slender turning, a term comprehending all long works of relatively small diameter ; the management of larger examples has been incidentally referred to in preceding chapters.

The piece for the shaft is securely mounted in a small, plain metal chuck, and supported by the point of the popit head. The terminal forms and mouldings are sometimes both first completed and polished at either end, while the piece is still strong; that most distant from the chuck, and its pin or screw for attachment to the bowl, being in all cases finished prior to any reduction of the slender stem. The whole length of the parallel portion is then a little reduced in diameter and turned true, after which a short length of about an inch, more or less, according to the size and length of the shaft, is further reduced with a small gouge or round tool, and finished to the required size with a narrow flat tool, the last held slightly tilted, as described page 303, so as to place both its corners free of the work. The reduction to size is commenced against the moulding and gradually completed towards the chuck, to careful measurement with the callipers or some other gage; after which, this short portion of the parallel stem is polished.

A second and shorter length is then reduced to size in the same way, commencing at the termination of the first and proceeding towards the chuck, but with the left forefinger placed around the work from below, so that the first joint or the tip of the finger may restrain the work in true revolution and support it against the thrust of the tool; and this is continually repeated upon shorter and shorter lengths, until the entire shaft is completed. Every length being carefully measured for diameter, more especially where it joins the preceding, and polished, before commencing the next. With increasing length a very slender stem runs risk of fracture from its gyrations; the popit head has then to be withdrawn, but the work may be restrained by being passed through holes, sufficiently large to allow complete freedom of rotation, pierced in one or more thin pieces of wood attached at intervals to the lathe bearers after the manner of the boring collar. The moulding and the pin or screw beyond it at the chuck end of the shaft, to attach the stem to the foot, is usually turned last, with the work still in the same chucking, or with the piece reversed, and carried in a long wood spring chuck.

Other equally slender stems are turned with a variety of small ornamental shapes, left at intervals, which appear as if threaded upon them; that about the center of the length being generally larger, while the base of the shaft springs from some appropriate ornamental foot. These works, often eighteen inches or more in height, are constructed in pieces of moderate length, attached to each other at the larger ornaments. A short length is indicated by fig. 762; this would be readily turned as one piece, solidly chucked in one of the screw or die chucks or driven into a plain chuck.

Fig. 762.

Transparent And Slender Turning 400400

The work as before is commenced at the opposite extremity to that in the chuck, and is turned in short lengths, every one of which is completed and polished before proceeding to the next. The piece if long is soon unable to sustain its own weight in the horizontal position, while its gyrations early require restraint; the wooden frame and cross threads, fig. 138, best meet both requirements, and two or more of these supports may be employed. The screw by which the lower end of every length is connected to the next, is cut by hand, or with the traversing mandrel, from the shoulder towards the chuck, subsequently to the completion of the piece, which is then severed from that remaining in the chuck, leaving the work suspended in the threads,

When the sphere shown in fig. 762, is of a larger size, in place of turning it in the solid with the stem, it would be chosen as an appropriate piece to attach two lengths of the latter. A solid turned cube or other rectangular figure, or a sphere containing some other turned solid, is frequently employed for the main central ornament of the stem; the general effect being increased by the contrast between their magnitude and the delicate slender stem by which they are supported.

To leave a column in the solid, not to interfere with its strength as a support and at the same time for economy of material, the furniture turner sometimes adds the piece to give additional diameter for a central or other ornament, in a manner different from any previously described. These works, although the antitheses of the delicate productions last mentioned, may be conveniently referred to here.

Fig. 763.

Transparent And Slender Turning 400401

The column, fig. 763, is first turned to its general proportions, after which the width of the part that has to receive the piece to give increase of diameter, is reduced below the level of its neighbouring portions, turned to a true cylinder, and the narrow surfaces thus formed above and below it, turned square to its axis. The piece to be added, shown shaded, usually required of the same material, is selected of straight grain and rather too large in diameter; it is first pierced with a cylindrical aperture carefully measured with the callipers to fit the cylindrical portion turned upon the shaft, after which its two surfaces are turned flat and true, until its height exactly agrees with the width reduced upon the shaft.

The annular piece thus prepared is then split with the grain into two halves, the two halves of the hole and those of the fracture, the cylinder and its two containing surfaces, are then all lightly coated with thin glue and quickly placed together; a screw clamp being immediately fixed upon them to force the two halves of the ring into contact with each other and the cylinder. When the glue has become hard, the shaft is again mounted in the lathe to turn the added piece to shape; this removes the marks left by the chisel or other tool used to split the ring, when, should a suitable piece of material have been selected and the work skilfully performed, the line of fracture is not easily detected and the completed shaft appears to be one solid.