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was especially heat treated after roll- ing and all holes were drilled. The reduction in thickness allowed due to the use of this special steel is given as 10 to 12 per cent. The EMPRESS OF JAPAN of the Cana- dian Pacific line built in 1930, is of mild steel throughout. In the larger and more distinguished Empress or BRITAIN completed this year, high elastic limit steel was used for about 70 per cent of the length, on the promenade and A decks and on the top side shell between these decks. In this vessel, it is of special interest to observe that no expansion joints have been provided. High elastic limit steel has also been used to some extent in the new MoNARCH OF BERMUDA. In selecting special quality steel it is important to make certain of req- uisite physical requirements to meet the conditions for which it is to be used, and that it is of reliable and uniform quality. The first can be readily established in the laboratory, the other is largely a matter of ex- _ perience. Shipbuilders have always’ been somewhat conservative, and rightly so, in regard to changes in the man- ufacture and use of materials. The use of alloy steel in nearly all other branches of engineering is increasing. In the marine field high pressures in boilers and in machinery is no longer a novelty, and it is but logical that the elastic and tensile properties of the material should keep in step. Con- siderations such as these provide the shipbuilder with food for thought, for, as so often happens, the specialty of today may very easily be the standard of tomorrow. 4. Notes on the Development of Cer- tain Materials Used in Ships of the U. S. Navy, by Rear Admiral George H. Rock (CC) U.S. N., vice president. The author states that it is the purpose of this paper to discuss some of the materials used in shipbuild- ing and some of the work which has been performed by the navy depart- ment through the bureau of construc- tion and repair in the preparation of specifications for shipbuilding mate- rials and the developments of new and improved materials. He takes up first, steel as the most important of shipbuilding material and points out that the bulk of the structural steel used in naval vessels is standard medium steel with mini- mum tensile strength of 60,000 pounds and minimum elongation of 25 per cent. Use is also made in naval vessels for strength members of so-called high tensile steel with a minimum tensile strength of 80,000 pounds and minimum elongation of 20 per cent. This, the author points out, is a silicon steel and unfortu- nately does not lend itself to being welded. He next covers the question of corrosion resisting steel. Then paints, heat insulating material, cot- ton bunting for flags, anchor chain. In connection with the latter the suc- cess of tests on cast steel chain as made by the National Malleable & Steel Castings Co. is reported. The favorable showing of cast steel chain in these tests led to the final decision that cast steel chain should be adopted as standard for navy use. The use of cast steel chain by the navy over a period of 10 years has demonstrated that periodic annealing is not necessary. Other materials considered are deck covering, aluminum furniture, manila rope and steel castings. Admiral Rock points out the op- portunities now presented to improve in material practice, but that long ex- perience with failures in materials under the exacting conditions of serv- ice aboard ship has bred a conser- vatism which must act against too sudden or too radical changes in such practice. The bureau is working to- ward securing the proper mean be- tween rapid material progress, so nec- essary at the present time in naval design and construction, and the ab- solute necessity of obtaining mate- rials which will give satisfaction and long life in service. Note: A discus- sion by W. J. Priestley of Admiral Rock’s paper appears on Page 35. 5. New Structural and Decorative Materials as Applied to Shipbuilding, by William E. Blewett, member. It is the intention of this paper, the author states, to call attention to certain structural and decorative ma- terials which possess characteristics of such value to the shipbuilder that their use would tend to improve the quality of our ships. In the paper each group of materials as far as practicable has been dealt with as a class. The properties which make each material particularly useful for ma- rine work have been noted, but no attempt has been made to pass judg- ment on their desirability. Deficien- cies, where they have been discovered, have been noted. Various methods of installations and treatment of some materials are described where the value of the material is dependent on proper handling, or where difficulties may be encountered in its use. In order the following materials are taken up: High elastic steels, rivets, aluminum, insulation, asphalt chocks, structural finishes, alloy steels for galleys, deck coverings, un- der which are included magnesite, mastic decking, sheet rubber, imita- tion stone, galley tile and parquet floors; composition materials: Plastic ornaments, bathroom material, swim- ming pool tile, metal sprayed mate- rial, hardwoods, hardwood finishes, and joiner bulkheads. This paper represents a very In- teresting and valuable contribution to the art of shipbuilding in the prop- erties of materials gained by experi- MARINE Rreview—December, 1931 ence and by experiments. It is a record for the benefit of others of experience gained. 6. Some Recent Developments in the Shipbuilding Art in America, by John B. Woodward, Jr., member. The preparation of this paper, the author points out, has been sug- gested by the fact that during the past ten years the papers dealing with the shipbuilding art have been few. He enumerates and discusses some interesting recent shipbuilding de- velopments. Shipbuilding is one of the broadest of the industries in its processes, problems and contacts. In pointing out that the free in- terchange of information among shipyards and ideas gathered from other industries have been an impor- tant element in the advance of the art, the author touches on one of the most vital things of the industry. This paper illustrated by views from various shipyards, will prove of great interest to everyone connected with shipbuilding, and as the author hopes, it may serve to lead others at fu- ture meetings to a more complete discussion of some of the points cov- ered. By the interchange of such in- formation it will be possible to build better ships at less cost and to this end all will profit. 7. Notes on the Launching of the T. 8. 8. Mariposa, by James B. Hunter, member. The launching of the Mariposa on July 18, 1931, at the Fore River plant of the Bethlehem Shipbuilding Corp. under somewhat difficult con- ditions, provides an example of the successful coordination of the func- tions of the operating and technical divisions of a large shipyard. This paper presents valuable in- formation covering the launching data of this ship, one of the largest merchant vessels built in the United States. Among the features covered are, the construction of ways and poppets; blocking and shoring; re- leasing and starting gear; checking and launching procedure. Curves are also given of observed data during launching. In conclusion the author points out that the successful launching of this vessel under very restricted condi- tions demonstrates that chain drags form a logical solution to the check- ing problem and that, when reliable data are available their effect is sus- ceptible to calculation within fairly close limits; also that close coopera- tion between the operating and technical division is of great impor- tance. The time spent beforehand in careful consideration of the prob- lem reduces final cost and leads to a much more orderly procedure on the actual launching day. ; 8. Interior Lighting Aboard Ships, by Samuel G. Hibben, visitor. Illustrated by a number of mod- ern ship interiors where the lighting 15