second-hand shops; these latter are pretty sure to stock "shoddy" foreign-made goods.
Compasses.—-These are instruments for describing circles. There art; several varieties; only a few of the more generally useful, however, are described here. The commonest form is that known as a half set," Fig. 15, which consists of a pair of legs of which one point is removable, and may be replaced by a pencil leg or " point," or by a pen or " ink point." c, Fig. 15, as they are termed in catalogues and a " lengthening bar," a, Fig. 15. this last is inserted into the socket of the compasses and the pen or pencil point inserted into the other end of the bar, for describing circles of large radius. Some instruments are fitted with movable needle points. These are too fragile for the inexperienced .student's use and should be avoided ; so also should those compasses having triangular " points," which make large holes in the paper and are difficult to set accurately. Round hard steel points fixed into the legs are the best, as shown at b, Fig. 15, and there should be a joint in the socket leg to enable the pen point to be set perpendicularly in the paper when the legs are opened out widely; preferably there should be a joint in each leg, as this considerably increases the working " span." The usual sizes of these instruments are 4J- in., 5 in. and 6 in. long. When only a half set can be purchased, and the small instruments mentioned subsequently are not obtained until advanced work is attempted, the medium-size set will be found the most serviceable, but if complete equipment is obtained at the start, choose the largest size in compasses and rjnallest in dividers and spring bow.
In choosing compasses perhaps the chief point to note is the lit of the joints; the legs should move " sweetly," without any jerk. Socketed joints should slide together tightly without shake throughout; and all joints should have screwed, not riveted pivots.
Dividers —These are compasses with solid or nonremovable legs ; they arc used for taking and transferring
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