OF PRACTICAL ENGINEERING AND ALLIED TRADES A PRACTICAL AND INDISPENSABLE WORK OF REFERENCE MACHINIST. We have concluded that it would be more advantageous to bind two volumes of this Encyclopædia in one volume. That is, volumes One and Two, Three and Four, Five and Six, Seven and Eight, and Nine and Ten, are each bound together; thus publishing the work in five bound volumes, instead of ten. THE NORMAN W. HENLEY PUBLISHING CO., s, simple læ. The tement of te in the .E. MAKING," ASSISTED BY A CORPS OF PRACTICAL MEN, EACH A SPECIALIST IN THE SUBJECT OF WHICH HE WRITES. HENLEY'S ENCYCLOPÆDIA OF PRACTICAL ENGINEERING AND ALLIED TRADES A PRACTICAL AND INDISPENSABLE WORK OF REFERENCE Encyclopædic in scope, thorough and practical in its treatment of technical subjects, simple and clear in its descriptive matter, and without unnecessary technicalities or formulæ. The Articles are as brief as may be and yet give a reasonably clear and explicit statement of the subject, and are written by men who have had ample practical experience in the matters of which they write. Edited by JOSEPH G. HORNER, A.M.I.MECH.E. AUTHOR OF PRACTICAL METAL TURNING," MODERN MILLING MACHINES," PATTERN MAKING," ETC., BTC. ASSISTED BY A CORPS OF PRACTICAL MEN, EACH A SPECIALIST enabling the head to be instantly drawn back. One of the commonest types in use, by the Geometric Tool Company, is shown in front view and in section by Fig. 1. There is a shank a held in the turret, and a body B, on which fits a cam ring c, holding the chasers D by cam grooves at their rear. It will be obvious that if c is revolved, the chasers must be moved a spiral spring fitted in a groove (see the front view), throwing the chasers off the thread. There is an arrangement at the back of the head, indicated in the face view, for altering the size which the chasers will cut, by means of a couple of screws, so that variations may be made in the diameters of the work. If desired, the die may be opened by the handle at the top, while |