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434 whus tole "ircle. the entire casting. As les run. into each other a short eee from the periphery, the final operation of removing the head is easily done by means of a hammer and cold chisel. The drill is mounted in an extension socket which is driven by a turret lathe or other con- venient tool. If reasonable care is ex- ercised in laying out, the holes befor2 drilling, the operation can be carried out without services of a skilled mechanic. THE MARINE REVIEW Record of War Work A circular recently issued by the Todd Shipyards Corp., deals with the com- pany's activities in repair and construc- tion work during the war. More than 250,000,000 tons of shipping were han- dled. This work included fitting out transports to carry troops to France, the rehabilitation of a number of dam- aged German liners, lengthening lake vessels, supplying engines and the re- October, 1919 fitting of yachts for use by the navy as scout patrol vessels and other emer- gency war work. Aside from this work, the company built mine sweepers for the navy de- partment, freighters and scout cruisers, Some of the vessels handled by the com- pany were the Grorce E. Warren, L. V. Sropparv, GeorGE HaAwtey, Curaca, Frep R. Ketiocc, Lorp DurFrerin, GrorGE WASHINGTON, PRESIDENT LIncoun, Mount VERNON and Hampure. etd Vote. Set With No Lead? | ees opening of the port to ad- mit steam into the cylinder of an engine while the piston is yet a short distance from the end of its stroke is properly referred to as lead, and is so nearly universally ac- cepted as an indispensable condition to the successful operation of a steam en- gine, that it seems almost a desperate proposition to oppose lead, according to Harry Stone in The Bulletin of the ioame Catri¢rs association. . The. text books on steam engineering advocate lead. The technical schools advocate and teach lead. The question of lead is seldom'. reterred to except (asa mechanical necessity for the smooth and economical performance of a steam en- gine. But is it? After more than 50 years' experience as stationary and marine engineer, the writer is decidedly opopsed to lead. With the slide valve set -with lead there are two points in the revolution of the engine where, instead of the steam driving the engine, the engine has to actually drive the lead steam back into the boiler against boiler pres- sure. Added to this is the greatly in- creased friction on the crank pin and journals, and it requires no -argument to prove that these deterrents retard the speed of the engine. The' lead steam is not wasted because it does not escape but it is a question whether it would not be as well for it to escape as for the piston to buck it back into the boiler. An absolutely convincing test of ae efficiency of the two arrangements, lead or no lead, can be made only by shift- ing the eccentric or altering the struc- ture of the slide valve in the same en- gine. This the writer has always done when possible, and found'.that engines of between 40 and 24 -inches stroke, will make from one to two revolutions more in a minute without lead than they will with lead. ~The argument advanced: by 'engineers in favor of lead, that lead steam is a necessity to cushion the. piston and bring the moving parts of the engine quietly to. rest at the centers, can be . the evil. graphically shown to be unnecessary by drawing a circle of any convenient size to represent the path of the crank pin in motion, and in the circle draw a supposed vertical diameter and dot its extremities to represent the centers. In this simple diagram it can easily be seen that the speed of the piston is greatest while the crank pin is sweeping through the middle of the side arcs of the cifcle and gradually diminishes as the crank approaches the center line where the piston is stopped and_ re- versed in direction by the compression which is provided for the very same purpose as lead, more smoothly and quietly than by the trip- -hammer impact of lead steam . Another objection to lead is, an en- gine will work slower under check without lead than it will with lead, be- cause it is the momentum of the mov- | ing parts of the engine that carries the crank past the centers. As the crank approaches the center, the -pressure of the lead steam and the increased fric- tion are again encountered, and unless the motion of the engine is great enough to generate sufficient momentum to overcome both, the engine stops. This resistance is sufficient to reduce the speed in ordinary running, one to two revolutions per minute, say one and a half. Then a ship driven by a wheel with blades set to .16-foot pitch and with 25 per cent slip, will lose 18 feet each. minute or 'nearly five miles in 24 hours. Of coutse this computation will vary with propeller wheels set to differ- ent pitch and 'slide valves set with different lead, but it gives an approxi- mate idea of the aggregate loss to the vessels through the mistaken idea of lead. The greater the lead, the greater The less the lead, even if it extend to setting the valve with an eighth of an inch steam lap, the more satisfactorily the engine works in all respects. It must be borne in mind that it is the momentum of the moving parts of the engine that carries the crank past the centers, and not the pressure of steam. The writer points out that he does not expect all engineers to agree with him unless they, or some of them, have had practical experience with both methods, lead or no lead, but he sets forth that the subject' is timely and 'worthy of discussion. System of Dry Lock Where a canal connects two rivers situated at different levels, and the usual chamber lock is necessary to pass traffic from the higher to the lower level, the water taken from the higher level stream is considerable. Sometimes tunnel sluices in conjunc- tion with an auxiliary basin are used, but in such cases the cost of pumping the water is high. To overcome these difficulties many schemes of dry lock have been elaborated, including hoists, railways, etc., for ferrying the traffic over from the high to the low level and vice versa, but the cost of these is generally prohibitive, owing to the heavy and expensive machinery which it is necessary to install. A German firm has patented a new system of ferrying ships, etc., used for canal traffic, which is said to com- bine the advantages of the existing railways or hoists and those of an ordinary lock. The new ferrying plant, which is shown in the accompanying illustra- tion, consists of an iron carriage, which carries a trough filled with water for holding the vessels to,be ferried.. The weight of the carriage is only to a-small extent borne by PLAN OF DRY LOCK SYSTEM