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8 MARINE REVIEW. Engineering Questions and Answers. CONDUCTED BY GEO. C. SHEPARD. Editors Marine Reyrew: My L, P. cylinder is 62// diameter and 48'" stroke, but working my 5-inch injection valve wide open I can only get 21/7 vacuum, and my feed water is 120°, Everything seems tight and air pump works well. What is the trouble? J. A. D. Buffalo, N. Y., March 3, 1893. The data you give is too meager for us to make a very positive answer to your question. Assuming that the initial pressure in the L. P. cylinder is 9 pounds, or 24 pounds absolute, and that you cut off at 3 stroke, the terminal pressure is 15 pounds at which pressure the weight of one cubic foot is .0387 pounds, and the capacity of the cylinder is 87.6 cubic teet, hence 3.39 pounds is the weight of steam expelled at each half stroke of the piston. Now 27 pounds of water to 1 pound of steam is a safe figure on which to compute the amount of condensing water required, in this case 91.5 pounds for each half stroke, or 14,640 pounds per minute at 80 revolutions per minute. With a vacuum of 24'" and a head of 8 feet, this requires an injection orifice of 21.6 square inches, so that, since these calculations are made with « very large margin, 5" isample diameter, and we would suggest tbat in fitting out you examine your injection valve and see if it does open wide when the lever is pulled way down. Paint the exhaust pipe with a very thick paint, especially at joints, and examine the air pump to see that the valves all seat tight. Everything else being in good order the construction of the condenser may be such that it cannot forma good vacuum. A thorough mingling of the exhaust steam and injection water is necessary--the more thorough mingling the more vacuum--and to meet the natural tend ncy of the steam to rise the nozzle should be as high as prac- ticable and should also divide the water into a fine spray or thin ribbons as possible; and then if in falling the water should be intercepted by inclined "baffle' plates arranged in such manner that falling off one in a sheet is caught by the next and so on, while the steam remaining will have to pass through these sheets of water and be further condensed, better results would be obt ined than if the nozzle was low in the condenser and the condensation de- pended upon the spray alone. Editors MarinE Review: The cards taken from the H. P. and I. P. engines of the boat I was on last fall show a loop on the steam ends. Could you tell me the cause and simple remedy. M. E. D., oiler, Chicago, II]., March 5, 1894. Your data is rather incomplete but we will jump at the answer and say that the loop shows that for some reason the steam is forced to a higher pres- sure than that of the steam chest. An excessive lead would not do that, un- less the compression was above what it ought to be, and we are inclined to lay the whole blame at the door of compression caused by too early closure of the exhaust. The remedy for this defect is found in cutting off the inside lap of the valves of the engines in question ; how much depends on the stroke of en- gine, travel of valve and lap of valve. Mr. Geo. C. Shepard, care MARINE REvIEW: I notice in your article on the slide valve that you make the statement that making the distribution of steam imperfect in the backward motion is of little consequence. Now I would like to disagree with you on this point, because if ever we want a perfect work- ing engine it is when we get on the bottom somewhere and try to back off. That is the only time in my experience that the engine is woiked her hardest, and if anything can be done with her valves that will enable her to develop a lot of power for a little while let it be done. S, E. A. Alpena, Mich., March 3, 1894. The jundamental principles concerning the propulson of steam vessels and the performance of marine engines were propounded in the seventeenth cen- tury--long before the discovery of the utility of steam--by Sir Isaac Newton in his Principia at atime when breezes and the brawn of oarsmen were the powers that moved, and a horse power was that developed by a good animal at the end of a sweep turning a windlass to raise coal from the mines, and, thoroughly demonstrated by the experience of centuries, they stand today, as then, true to all motions of matter, men and society. In Newton's own words they read: 1. Every body continues in its state of rest or of uniform motion ina straight line, except in so far as it may be compelled by an impressed force to change that state. 2, Change of motion is proportional to the impressed force and takes place in the straight line in which the force acts. 3. To every action there is always an equal and contrary reaction. To "Harry," New York: Your questions and eards received but before attempting to answer would ask the sequence of rotation of the cranks and the travel of the valves. Ep. Subscribe for the official report of the Engineering Congress through the Marine Review. Price $10. Sold only on subscrip- tion, to be paid for when delivered. The Meeting of Steamboat Inspectors. An advance proof of the circular reporting the proceedings of the recent annual meeting of the board of supervising inepectors of steam vessels has been received from Washington. The board adopted a new form of sample for steel boiler plate which differs materially from the old form of sample and is described by diagrams in the circular. In the matter ot safety valves on water tube boilers an amendment to the rules provides that all spring-loaded safety valves for boilers of this type re- quired tocarry a steam pressure exceeding 175 pounds per square inch shall be required to havean area of not less than 1 square inch to 6 tgquare feet of the grate surface of the boiler. This shall be construed to prohibit the use of two safety valves on any water tube boiler, provided the combined area ofsuch valves is equal to that required by rule for one such valve. But in no case shall any spring-loaded valve be used in lieu of the lever weighted safety valve without first having been approved by the board. The lever and fulcrum link must be made of wrought iron or steel, and the knife-edged fulcrum points and bearings for the points must be made of steel and hardened. But the cham- -- bers and saddle flanges of this and all other types of safety valves attached to boilers may be made of cast iron or other suitable material. By achange in the rule prescribing the experience ashore required of ap- plicants for marine engineer licenses, the machinist who has served an ap- prenticeship and has had three years' experience asa machinist in a marine engine works is placed on an equality with all other machinists, as well as stationary and locomotive engineers and graduates of mechanical schools. All must serve one year ona steamboat before a license can be secured. For- merly the machinist who had served an apprenticeship and three years at his trade in a marine engine works could, according to the rules, obtain a Jicense as scond engineer without spending a year aboard a steamer. Changes in the pilot rules refer entirely to western rivers. Enormous Tonnage Increase. A Detroit vessel owner who claims that the present depression in freights on the lakes is due almost entirely to overproduction of freight carrying ton- nage, has prepared, from reports of the United States commissioner of naviga- tion, the following unique summary of tonnage built on the Jakes: For the seven years ending June, 1872..........sessesreecneeseererers 304,907 For the seven years ending June, 1879..........seeseseeseeeeseenecrens 265,905 For the seven years ending June, 1886............seessesersesereeneees 261,067 For the seven years ending June, 1893...........ssseseseceseeeeseeeees 630,293 He argues that the conditions are even worse than these figures indicate, for the tonnage built in the first two periods was largely sail, with a load draft of not over 14 feet, and a season's capacity of not over nine trips, while the tonnage built for the last two periods was largely steam (especially is this so for the seven years ending June, 1893), with the load draft fully 15} feet and a season's capacity of not less than 16 trips. Applying this increased load draft and extra trips to the enormous output of new tonnage for the past seven years, gives a tonnage capacity of over 1,100,000 tons, as compared with the tonnage capacity of not over 900,000 tons for the three previous periods, or the twenty-one years ending June, 1886. For the year ending June, 1887, the first year of the last period, the output of new tonnage was only 56,488 tons, but the average yearly output of the following six years had risen to 95,635 tons, and the banner year ending June, 1891, the output was 111,856 tons. As the financial scare of November occurred in that year, a slight check was ex- perienced, for the output the next year fell to 45,969 tons. The check, how- ever, was only temporary, for the output for the year ending June, 1893, was more than double the preceeding year, being 95,635 tons. These figures are correct, as they correspond with the statements from the office of the commissioner of navigation published of late years in the REVIEW. At the annual meeting of the board of the supervising inspectors of steam vessels recently concluded in Washington, types of coil and pipe boilers pre- sent+d by thirty-nine individuals and firms whose names follow were approved, Lewis Saunders, Lawrence, Mass,; Perkins & Richmond, Grand Rapids,Mich.; E. P. Clark, New York, N. Y.; John H. Lutz, Michigan City, Ind.; Henry Haenel, St. Augustine, Fla.; Lee H. Stephens, New Albany, Ind.; I. G. Mor- gan, Seattle, Wash.; Charles L. Seabury, Nyack, N. Y.; George H. Holmes, Gardiner, Me.; Charles W. Foster, New Haven, Conn.; Babcock & Wilcox, New York, N. Y.; Anson C. Dearing, Detroit, Mich.; the Rochester Machine Tool Works, Rochester, N. Y.; Hampden Hyde, Rochester, N Y.; Charles DeVore, Philadelphia, Pa.; Emil Volk, New York, N. Y.; J. B. Jardine, San Francisco, Cal.; B. Louis Toquet, Westport, Conn.; L. Boyer's Sons, New York, N. Y.; G.R. Jackson, McKeesport, Pa.; George W. Arrowsmith, Fort Niagara, N. Y.; George L. Wright, North Andover, Mass.; W. W. Moore, Kugene, Ore.; J. J. Driscoll, Stapleton, N. Y.; Charles Ward, Charleston, W. Va. (coil boiler;) Charles Ward, Charleston, W. Va., (navy horizontal pipe boiler;) R. Muroe, & Son, Pittsburg, Pa.; Samuel I. Williams, Baltimore,Md.; John A. Flajole, Bay City, Mich.; D. Rousseau, New York, N. Y.; the Coul- ter and Mc Kenzie Machine Company, Bridgeport, Conn.; John J. Brown, Baltimore, Md.; George E. Dow, Seattle, Wash.; L. D. Daais, Erie, Pa.; John A. Duggan, Boston, Mass., (Christiansen Marine Boiler;) Robert R. Zell & Co., Baltimore, Md.; D. Y. Williams, South Haven, Mich.; E. U. Gibbs, El- mira, N. Y,