THE WORK OF THE MACHINES 223 turning for running them on the spindle only, and for massive work to support them on an annular ring nearly as large as the diameter of the table. Very many machines have two work-holding tables. At the opposite ex- treme, machines of large dimensions will take pieces from 30 to 40 ft. in diameter. On all, a cross-slide, much like that of a planer, receives the saddles that carry the tool slides. Frequently a turret is mounted on a slide, carrying a battery of tools. Boring and turning are performed simultaneously, and turning may be done from two tool-holders on opposite sides of a diameter. A photograph of work being done on the machines by Messrs. Webster & Bennet, Ltd., of Coventry, will serve to indicate the utilities of the boring and turning mills equipped with turrets. In fig. 57 two distinct castings are being tooled on one machine, bored, turned, and faced, in charge of one attendant. Loose chuck jaws hold the work in each case. DIVISION V Milling Machines.—These are all derived from the Lincoln millers, to which they bear no resemblance beyond the fact that they all employ rotating cutting-tools with many teeth. The Lincoln Machine.—This is used for plain horizontal and face Fig. 58.—Slab Milling on a Plain High-power Cincinnati Machine. Material Steel, width cf cut 5 in., depth £ in., feed 19 in. per minute. Material removed 24 c. in. per minute.