2. Turning is performed in a _lathe_, an apparatus constructed in various ways, according to the particular purposes to which it is to be applied, although, in all cases, the general principle of its operation is the same. The kind represented in the above picture, is used for plain or circular turning in wood. On examination, it will be perceived, that two wheels of different sizes make essential parts of it. On the extended axle of the smaller one, is fastened the piece to be turned; and immediately in front of this is the _rest_, on which the cutting instrument is supported during the performance of the operation. 3. When the material to be turned is wood, it is commonly cut to the proper length with a saw, and brought to a form approaching to the cylindrical by means of an axe or drawing-knife. It is next fastened in the lathe. This is done by different means, varying according to the particular form of the thing to be turned. In plain circular turning, as applied to bed-posts, legs of tables, and rounds for chairs, the piece is supported at each end. That at the left hand is driven upon a piece of steel, which has been screwed upon the extended axle of the small wheel; and the other end is fixed upon a steel point, placed in an upright moveable piece called a _puppet-head_. 4. In case the wood is to be turned on the inside, as in making a bowl, cup, or mortar, the piece is supported altogether at one end, by means of a hollow cylinder of wood, brass, or iron, called a _chuck_, which receives it on one side, and on the other is screwed upon the end of the axle. The axle is sometimes called the _mandril_, and any extension of it, by means of a piece added to it for a centre, on which anything may be turned which will admit of a hole through it, is denominated an _arbor_. 5. The tools used in turning wood and ivory, are _gouges_ and _chisels_ of different sizes and shapes. In using these, they are placed upon the _rest_, and brought in contact with the revolving material of the proposed figure. The gouge is employed in cutting away the rough exterior, and the chisel, in producing a still further reduction, and a greater smoothness of surface. 6. In working in very hard wood and in ivory, the _grooving tool_, a sharp pointed instrument somewhat similar to the graver, is used in the first part of the operation; and by this the grain of the substance is cut into contiguous grooves, and prepared for an easy reduction by the chisel. The instruments for turning metals are numerous, but they differ in some respects from those for cutting wood.