Page:International Library of Technology, Volume 53.djvu/22

 pivot joint in which the head of each leg is shaped like a disk and the two disks are held together in a fork-shaped brace either by means of two pivot screws or by one screw penetrating both disks. The brace that forms a part of this

joint is generally provided with a handle, as the shape of the joint makes it rather awkward to hold the compasses by the head as is usual with instruments provided with tongue joints. In Fig. 9 is shown a common style of pivot joint. 8. The following suggestions for handling the compasses should be carefully observed by those who are beginning the subject of mechanical drawing. Any draftsman who handles his instruments awkwardly will create a bad impression, no matter how good a workman he may be. The tendency of all beginners is to use both hands for operating the compasses. This is to be avoided. The student should learn at the start to open and close them with one hand, holding them as shown in Fig. 10, with the needle-point leg resting