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June, 4919 below. New Orleans, by a wrecking company. Chicago Bisso was sunk in collision with a freighter some months ago, and the contract price for raising her has been fixed at $100,000. She belongs to the W. -A. Bisso Towing & Coal. Co; Crank Slotting Machine In the general run of marine work, both on new equipment and repairs, many pieces of irregular contour or with enclosed rectangular surfaces re- quire finishing. Many parts also re- quire keyseating. Work of this nature is admirably done on _ the slotting machine as the downward cutting action does not obliterate scribed start: of the tool's down stroke does not throw up a burr. A slotting machine particularly adapted for marine work is shown in the accompanying' illustration. "This machine has an 18-inch stroke and is a product of the Putnam Machine Co., Fitchburg, Mass. The base and col- umn are cast in one piece to insure rigidity while the cutter bar. has ample bearing surfaces to eliminate chattering while taking heavy cuts. The cutter bar is counterbalanced through the medium of a weight car- ried on a forged-steel arm. The guide carrying the cutter bar is adjustable so that it can be conveniently placed near the work in process of ima- chining. The relief apron at the end of the cutter bar is provided with both horizontal and _ vertical tool clamping surfaces which permits the machine to handle a wide range of work. The clamping surfaces are pro- tected against wear by hardening and are serrated to insure a positive tool grip. The hinge is placed well back and low down to insure positive and quick relief of the tool on the return stroke. A spring tension at the top of the relief apron is controlled by a bolt. This feature permits of ready adjustment or allows the apron to be clamped rigidly to the cutter bar in cases where this is advantageous. The quick-return device is said to be simple and efficient. It consists of a link connecting the main driving gear to a crank keyed to the shaft that actuates the cutter bar. The holes in the link are equipped with bronze bushings in which steel pins work. The parts are so proportioned that the cutter-bar speed is practically uniform throughout the cutting stroke with a return ratio of 2 to 1. All shafts are finished by grinding and all wearing surfaces are accurately scraped to a bearing. The lines because the cutter bar has eight speeds -which are provided by a 4-speed gear THE MARINE: REVIEW : ob3 SLOTTER WITH 18-INCH STROKE PARTICULARLY ADAPTED FOR MARINE WORK box and 2-speed countershaft. The feeds are actuated bya. cam on the erank-disk Shaft. -. All "feeds are en- gaged when tie cutter. bar is iat the top "ol its Stroke." "The 'rocker arm supporting the feed pawl is equipped with a slip ttiction. so" that] man obstruction is met with, the friction slips. This prevents serious breakage in cases where the operator is neg- ligent about throwing out the feed when planing to a shoulder. The circular platen is graduated at its periphery to insure close settings and is equipped with T-slots for ac- commodating strap bolts. It can be securely clamped in any position de- sired by four corner clamps. The compound table, on which the circular platen rides, is supported for its full width on the carriage. Thread Cutting Tool In the manufacture of engines and other marine equipment, it is common practice to cut, many threads on the engine lathe as this tool affords a ready means for that purpose. All lathe-cut threads are not accurate, however; which is. generally due to the fact that the workman it properly. is some - times indifferent about grinding the tool to the correct angle or setting Again, a_ single-point. tool, quickly becomes dull. To provide a thread cutting device that would overcome these difficulties, the Rivett Lathe & Grinder Co., Bos- ton, developed the device shown in the accompanying illustration. This tool carries a cutting unit having 10 teeth, which is rotated, one tooth at a time, through the medium of a convenient lever. The first tooth cuts a light chip the full width of the thread, the second one takes a slight- ly deeper cut and s6'.O0n until the tenth tool has passed over the work. which finishes the thread. Through this method, the rapid dulling of the point of the tool is avoided. The principal parts of the device are the sub-base, base, eccentric cutter arbor, operating lever, clamping plate, micrometer stop and cutter. The sub- base is mounted directly on the tool block of the lathe and is secured in place by a hollow-head cap screw and a nut in the T-slot. The arbor that carries the cutter is made of tool steel, hardened, ground and lapped to a good fit. It is made conical in shape to permit of ready adjustment in case of wear. The