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By H. J. Struth

The benefits of proration of oil production were perhaps more concretely realized in 1932 than at any time since the oil industry adopted nation-wide production control. Reduced output of crude petroleum, which brought the daily average of the United States down to approximately 2,000,000 bbl. from a peak in 1931 of more than 2,600,000, had a telling effect on the trend of oil prices. Mid-Continent crude was advanced in price from 776, for 36-gravity oil, to $1.04 a barrel. California crude, of 26-gravity at Signal Hill, moved forward from 736 to 976 a barrel. Pennsylvania crude, the only exception to the upward trend, rose in price from $1.82 per barrel to $2.02, only to react to $1.72. This was due to local conditions which necessitated an adjustment to overcome competition from other areas of the United States. East Texas continued to exert a far-reaching influence on the crude and gasoline market during 1932. Despite the fact that oil prices were advanced in most fields, large quantities of oil were produced in East Texas in violation of state proration orders, and sold in the market at prices considerably below official postings. This created competitive conditions in the gasoline market that were felt by all refining centers of the United States. The quantity of gasoline produced from cheap East Texas crude was not large, but the volume was sufficient to influence prices in practically all sections of the country. Thus, while the industry's' economic situation showed visible improvement statistically, the unreported and unseen statistics originating in East Texas proved to be an insurmountable obstacle to the economic betterment that was otherwise apparently justified. Somewhat surprising to many was the fact that gasoline consumption was maintained within 10 per cent of the preceding year. Domestic consumption showed only a net decline under 1931 of about 8.5 per cent; exports dropped in volume to the extent of about 23 per cent. As a matter of fact, domestic gasoline consumption was only about 1.4 per cent less than it was in the predepression year of 1929. Exports, however,

Jan 1, 1933

By C. W. Mac Gregor

THE observation of the flow layers, or Lüders' lines, produced in mild steel when it is stressed into the plastic range often provides considerable useful information for the study of the fundamental mechanism of the plastic flow of metals. It is a commonly observed fact that as soon as the upper yield point in a mild-steel tensile-test bar is passed, an unstable condition develops in the equilibrium, the load on the testing machine drops and if the surface of the bar contains a thin mill scale, the latter begins to flake off rapidly along certain "lines." These "lines" are in reality traces of wedge-shaped flow layers and are formed by the inter-section of the surface of slip and the surface of the bar. The average plane of the flow layer itself has been found by various experimenters to be inclined at an angle of approximately 45° to the axis of the test bar. In a body of more complicated shape stressed in possibly a different man-ner, the tangent planes to the flow layers at each point seem in many cases to be inclined at an angle of about 45° to the principal stress direc-tions at the point. As examples of the latter may be mentioned the logarithmic spirals obtained when a rivet hole is punched in a thin plate, or when a tube is subjected to internal pressure only, etc. Hence if the flow layers are observed from an experiment, the shear-stress trajectories -the curves indicating the directions of the maximum shearing stresses in the body-may then be approximately determined. Since the latter curves form an orthogonal family inclined at 45° to the principal stress directions, the family of principal stress trajectories, or the curves indicating the directions of the principal stresses, may be thus obtained. Although the discontinuous type of stress-strain curve at the yield point is commonly observed with test bars of mild steel, more recent experiments have shown that this is by no means the only material exhibiting this interesting phenomenon. A similar effect has been observed in zinc and cadmium crystals, by Becker and Orowan;1 in duralumin and other aluminum alloys, by Dawidenkow, 2 Elm,3 Fell, and others; in copper and copper-alloy crystals, by Elam;5 in brass by Elam;5 in brass wires by deForest;6 in higher carbon steels, tungsten steel, and

Jan 1, 1939

Denver, the Mile High, Queen City of the Plains, your host for AIME's 99th Annual Meeting has many exciting and picturesque places for you to visit during your stay. A host of restaurants cater to every taste; supper clubs and theaters provide nighttime entertainment; there are sports facilities and a plethora of shops for the ladies. When it comes to dining out, there are many excellent restaurants within walking distance of the Denver Hilton --among them, three in Brooks Towers: the Gitana, the Boston Half Shell serving the finest seafood, and Marvelous Mary's. In the Larimer Square area there in the Bratskellar with a true Germanic atmosphere and Sperte's Laffite offering a typical New Orleans setting.

Jan 1, 1970

NEW YORK SECTION ALLEN H. ROGERS, Chairman, H. C. PARMELEE, vice-chairman, FOREST RUTHERFORD, Vice-chairman, W. S. DICKSON, Secretary, 71 BROADWAY, NEW YORK, N. Y. J. E. JOHNSON, JR. F. T. RUBIDGE, Treasurer, P. G. SPILSBURY A meeting of the New York Section was held at The Machinery Club on Friday evening, Oct. 4, 1918, The Chairman, Allen H. Rogers, presiding. The CHAIRMAN.-MOST of us, I suppose, have been affected more or less by The request of The Fuel Administration that we leave our automobiles standing in The garages on Sundays. We shall all be interested in hearing about The situation that has called forth This, request, and The Oil Administrator, Mr. Requa, has kindly come from Washington to Tell us about it. MARK L. REQUA.-I am very glad To Tell you about the oil problem during This war period. The United States is supplying by far The greater part of all The petroleum products consumed in Great Britain, France and Italy. In addition To This, we have had To supply a marked increase in our domestic consumption, not only of The refined products, but of fuel oil as well. The combination has put a strain on The oil industry, which it is very difficult To meet. The oil companies, being under contract, had no option as To who should get Their oil first, and They were delivering pro rata To everybody; manufacturers of furniture were getting oil with The same regularity as Those who were making aeroplanes or munitions, and The oil companies felt that something should be done. The first order with which I had. anything To do was The priority list for The delivery of fuel oil. That list contained 12 classifications, beginning with bunker fuel and railroads, and you will realize The complexity of The situation when you hear that munitions plants are in class 11. The priority list held during The winter, but transportation became so bad, because of The number of ships that were Taken for trans-Atlantic use, that some of The oil companies were not able To deliver more Than about 60 per cent. into class 5, and nothing beyond that point. To add To the Troubles, the Tank-car mileage fell off. The average for 1917 was about 36 miles per car per day. in January, 1918, it dropped To about 8 miles, and it must have been nearly zero in The early part. of February. Because of The extremely severe winter, furthermore, pipe lines were not delivering anywhere near Their normal capacity. A new priority list has recently been promulgated, introducing a few slight changes. Natural gas has been brought under its provisions, and it has been extended To include The Pacific Coast, which was not considered necessary last winter. The situation in The gas industry is not satisfactory; it is estimated that There will be a decrease of 10 To 20 per cent. in The quantity of natural gas available This winter, as compared with last winter.

Jan 11, 1918

By Ervin E. Underwood

IT has been recognized for many years that dis-persed particles have great value in raising the creep resistance of metallic alloys. In fact, some of the most successful high-temperature alloys owe their superiority to this factor above all others. A recent observation by Glen1," indicates that even better high-temperature resistance to deformation results in alloys capable of two successive precipitation reactions. The ramifications of this finding are of great interest. Unfortunately, our understanding of the reasons for such notable improvements has not kept pace with technical developments. In an effort to uncover some of the basic facts governing strengthening by particles, a program was initiated at the Battelle Memorial Institute with the primary goal of comparing creep strengths in single-phase and two-phase (precipitating) alloys. The effects of precipitation from solid solution on the creep properties of alloys are generally such that the resistance to creep is increased. However, if alloys are heat treated to different degrees of hardness before creep testing, it is often found that those possessing the maximum hardness initially do not necessarily have the maximum creep resistance. Depending on the stresses and temperatures involved other structures may prove more desirable. Considerations of the above nature indicate the importance of defining the initial state of the alloy. Here, it was decided to start with quenched single- phase alloys in which precipitation and creep deformation proceed concurrently. Equipment and Experimental Procedures Preparation of the Specimens—Four 25 lb ingots were prepared from 99.999 pct Cu and 99.996 pct Al to compositions of 1, 2, 3, and 4 wt pct Cu. Spec-trographic and chemical analyses are listed in Table I. After heat treatments and intermediate reductions, the alloys were cold rolled to 1/8 in. thick sheet. The final cold reductions amounted to 50, 40, 20, and 10 pct for the 1, 2, 3, and 4 pct Cu alloys, respectively. The specimens for creep testing were machined into tensile flats 7 in. long, 3/4 in. wide (at the shoulders), and 1/8 in. thick. The reduced sections were 1/4 in. wide and 21/2 in. long. After heat treatments at 540°C to an ASTM grain size of 1 1, the specimens were quenched into water at room temperature, then electropolished in a glacial acetic acid and perchloric acid solution. The gage marks were Knoop impressions placed 2 in. apart on the reduced sections. Blanks of 1 x 1 in, were cut from the same sheets for the age hardening runs and were given the same grain size heat treatments. The specimens and blanks were stored in a refrigerator at —40°C until needed for testing. Creep Measurements—Creep tests were conducted in a constant temperature room which was maintained at 26° ±1°C. A split-type, hinged, vertical-tube furnace was mounted on a horizontal track so that the specimen could be enclosed suddenly. Thus, it took about 15 min for the specimen to come within 5°C of the test temperature. The temperature variation along the specimen was controlled to about

Jan 1, 1958

By AIME AIME

CONVENTION plans for the A.I.M.E. Regional Meeting to be held on the Minnesota Iron Range Aug. 12 to 1.5 are being completed to give the visiting member?s from all parts of the country a wide variety of technical and recreational features. High spots of the social events are the official dinner, dance, luncheon and golf: and of course, special provision is being, made for the entertainment of visiting ladies. The technical sessions will fit in with scheduled trips to view all phases of mining, beneficiation and transportation of iron ore. Men from the West and Southwest will find much of interest in the detail of the mining operations. A trip to the steel plant of the

Jan 1, 1941

W. H. SHOCKLEY, Chairman, FRANK H.-PROBERT, :Vice-Chairman, T. A. RICKARD, Sec.-Treas.; 420 Market St.,. San Francisco, Cal. C. C. BRAYTON, J. F. NEWSOM. A Meeting of the San Francisco Section was held on May 7, 1917. Chairman Shockley was in the Chair. The Section was honored by the presence of President Moore and Secretary Stoughton of the Institute. C. W. Merrill introduced President Moore, who then spoke to the Section on the Aims of the Institute. He discussed the possibility of improving the standards of membership by introducing a classification of membership. The present rigid investigation of applicants was pointed out by him. He spoke of the important influence that the local Sections can exert on the Institute and of the importance of sociability and informality at the meetings. Secretary Stoughton, who was introduced by the Chairman, emphasized somewhat the same points. He mentioned the need for making the Bulletin of the Institute more, interesting than it is at present, this to be accomplished by raising the necessary funds by increased advertising. He asked for an expression of opinion on this point. He. said that the employment department of the Institute is now used extensively. At the request of Mrs. Mark L. Requa, Mr. Stoughton. announced that a San Francisco branch of the Woman's Auxiliary of the, Institute was being formed and asked that the ladies of the members' families send in their names to Mrs. Requa or to the Secretary of the Institute.

Jan 10, 1917

NEW YORK SECTION J. E. Johnson, Jr., Chairman Edgar Rickard, Vice Chairman. D. M. Liddell, Secretary, 7 Wall St., New York, N.Y. C. A. Bohn, Treasurer John V. N. Dorr Lewis W. Francis. The annual meeting of the New York Section was held on Wednesday, June 6, with about 40 members in attendance. The treasurer re a brief summary of-the financial statement for the year, and the secretary's report was read. These reports were ordered placed on file together with the report of the auditors for the two previous years.

Jan 8, 1917

NEW YORK LOCAL SECTION Executive Committee L. W. FRANCIS, Chairman WILLARD S. MORSE, Vice-Chairman THOMAS T. READ, Secretary, Woolworth Bldg., New York, N. Y J P. A. MOSMAN, Treasurer Louis D. HUNTOON Since the annual meeting in February, the New York Section of the Institute has held three meetings. The meeting-on March 10 was held in conjunction with the American Society of Mechanical-Engineers and the American Electrochemical Society, at the Engineering Societies Building. The papers of the evening were devoted to records of progress in the Processes for the Photographic Reproduction of Natural Colors. The speakers of the evening were F. E. Ives, one of the earlier workers in color photography, Westley Allison, C. W. Robinson, George F. Clyfton, John B. Taylor, and Henry Hess. The April meeting was held on April 22 at the Institute headquarters, and the topic for discussion was Sanitation in Mining and Metallurgical Work. The principal paper was by J. W.. Luther, chief surgeon of the New Jersey Zinc Co. This was followed by a similar paper by Charles L. Close, secretary of the Welfare and Sanitation Committee of the United States Steel Corporation, and by an account of the sanitation work done in Cuba by the Spanish-American Iron Co., which was read by the Chairman, in the absence of Charles F. Rand. Following these papers general discussion was indulged in.

Jan 6, 1914

By Henry N. McCarl

[The Construction Materials section contains the following Chapters: Aggregates Cement and Cement Raw Materials Crushed Stone Dimension and Cut Stone Lightweight Aggregates Gypsum and Anhydrite Sand and Gravel Insulating Materials-Thermal and Sound Slag Roofing Granules] Mineral aggregates are those natural and manufactured industrial mineral and rock materials that provide bulk and strength in portland cement concrete, bituminous concrete mixes, and plaster or stucco surfaces. They may also provide special characteristics such as thermal and acoustical insulation, weight, surface textures, abrasion resistance, and impermeability to various concrete products and mixes. Most aggregates are relatively inexpensive materials, but despite their low unit value, the tonnages consumed each year in the United States and throughout the" world make mineral aggregates by far the leading industrial mineral and rock materials both in terms of volume (tonnage) produced and value consumed. The major use of mineral aggregates is in concrete. The low cost, high bulk aggregates tend to keep concrete construction costs at levels competitive with other building materials. Other major uses of aggregates include highway and railroad base or ballast materials, graded fill, and various industrial uses such as metallurgical and chemical fluxes and raw materials-these latter uses are often considered nonaggregate uses of mineral aggregate materials. The per-ton value of mineral aggregate materials at the production plant in 1980 and 1981 varied from $2 to $5 for most sand and gravel and crushed stone, $3 to $6 for air-cooled slag, $7 to $20 for expanded slag and expanded clay or shale aggregate, to as much as $165 to $320 for expanded perlite or vermiculite. The expanded lightweight aggregates have been dramatically affected by increasing fuel costs. It is ironic that the specialized aggregates used as insulating materials to conserve energy cost so much more to produce due to the high proportion of energy consumed in their production. The first four parts of "Construction Materials" deal with the utilization of four major mineral aggregate types: Crushed Stone, Lightweight Aggregates, Sand and Gravel, and Slag. While the focus will be on the use of these industrial minerals and rocks, there will also be some coverage of sources, mining and production, especially in those cases where they are not discussed in the Commodity section of this book.

Jan 1, 1983

NEW YORK SECTION J. E. JOHNSON, JR., Chairman EDGAR RICKARD, Vice Chairman D. M. LIDDELL, Secretary, 7 Wall St., New York, N. Y. C. A. BOHN, Treasurer JOHN V. N. DORR LEWIS W.. FRANCIS The following minute was unanimously passed at a meeting of the NEW YORK SECTION AMERICAN INSTITUTE OF MINING ENGINEERS held on the evening of June 6, 1917, two regular meetings having been adjourned by unanimous consent until this date out of respect to the memory of the late Chairman of the Section. Minute The death of our beloved fellow member DR. DAVID H. BROWNE one of the foremost metallurgists and one of the most brilliant and original thinkers in the profession of mining engineers, the chairman for the past two years of this section, has caused throughout a wide circle of

Jan 9, 1917

• Phelps-Dodge Corp. signed an agreement with the Defense Materials Procurement Agency to increase copper production from the east ore deposit of the company's Copper Queen branch at Bisbee, Ariz. The company agreed to undertake a $25 million expansion program, including construction of a concentrating and leaching plant at the Bisbee mine and enlargement of the Douglas smelter. The Government agreed to buy the first 112,500 tons of the first 150,000 tons produced at 22e per lb if the company could not sell at a higher price. The new facilities will have a yearly capacity of 38,000 tons and should be in production by late 1954 or early 1955. • American Smelting & Refining Co. has started construction of a new building to house the Central Research laboratory at South Plainfield, N. J. It will have approximately 75 individual laboratories and an equal number of offices and shops. Modern apparatus to be installed will include electron microscopes, electric and fuelfired furnaces, miniature copper refineries and zinc plants, wire drawing machinery, and large pilot plant laboratory. In the new building scientists study the base metals, and the development of new uses for a number of Asarco by-products, arsenic, and little

Jan 11, 1951

NEW YORK SECTION Executive Committee, DAVID H. BROWNE, Chairman., JOHN H. JANEWAY, Vice-Chairman, F. E. PIERCE, Secretary, 35 Nassau St., New York, N. Y. P. A. MOSMAN, Treasurer, LEWIS W. FRANCIS, BENJAMIN B. LAWRENCE. At a meeting of the New York Section, held at the Machinery Club on Jan. 19, 1916, the topic, for the evening was The Problems of the Naval Consulting Board, on which board are four prominent members of the Institute. The speakers of the evening were W. L. Saunders, president of the Institute, Dr. L. H. Baekeland, and Commander A. B. Fry, chief of staff of the New York Naval Militia. After Chairman Browne had laid before the meeting certain business matters, he introduced President Saunders, who presided during the speech making and delivered the first speech. The letter from President Wilson to Mr. Saunders and the presidents of the other national engineering societies, inviting their cooperation in a scheme for mobilizing, as it were, the industrial capacity of this country, had just been made public (see a previous page of this Bulletin) and President Saunders described in considerable detail the origin, purposes, and scope, of the work to be undertaken in this direction. Each of the five national scientific societies is to select a representative from its resident members in every State of the Union, that is, the mining engineers will have 48 representatives, likewise the electrical engineers, the chemists, the civil engineers, and the mechanical engineers. Thus, there will be a representative body or board of five members in every State, one from each of the five societies or institutes. Each committee will investigate the manufacturing and producing possibilities in its own state, and will gather information as to the capacity of every industry which may be capable of supplying things that are needed for the sinews of war. Industrial preparedness means something more than mere capacity to make shells. The field covers food, clothing, hospital equipment, motors, animals, telephones, telegraph and railway accommodations, and a myriad of small details.

Jan 3, 1916

The 48th convention of the International Union of Mine, Mill and Smelter Workers, held in New York City recently, saw delegates vote funds for a new organizational drive expected to begin immediately. John Clark, union president, told members in his keynote speech, that the union would be in a better position to make demands if it extended its membership to all phases of the nonferrous -industry. He told the 250 delegates that union leaders have already laid extensive groundwork for the campaign. Clark said: "I am proposing here that we concentrate on organizing during this coming year. I am proposing that we throw a heavy amount of re sources in organizing. That means financial resources as well as re- sources of staff ."

Jan 1, 1952

•Mineral Development Corp. of Salt Lake City, Utah purchased the Somerset and Oliver coal mines from the Kaiser Steel Corp. The mines are located at Somerset, Colo., about 75 miles east of Grand Junction, Colo. Somerset Town, with housing for 600 persons was included in the transaction. The mines employ 115 miners and have a combined capacity of 1750 tons per day. The Minerals Development Corp. is headed by Claude P. Heiner and is controlled by Godfrey L. Cabot, Inc. of New York and Boston. The Cabot Company is a major producer of carbon black. • The Dept. of Interior has announced that the name of the Defense Minerals Administration will be changed to Defense Minerals Exploration Administration. The new name of this defense agency more nearly describes its duties, since the mineral programming, procurement and claimant functions of the former DMA have been transferred to the Defense Minerals Procurement Agency. C. O. Mittendorf, formerly acting administrator of DMA, is serving as acting administrator of the new DMEA.

Jan 1, 1952

U.S. Signs Pact With Miami Copper Miami Copper Co., of Arizona has agreed to mine lowgrade copper ores in an extension of its Globe-Miami mining district operations at a guaranteed price of 27.35[] per lb, under a contract signed with defense Materials Procurement Agency. Terms of the contract call for delivery of 230 million lb of refined copper between 1955 and 1962. DMPA said highgrade ore in the de posit will soon be exhausted and it is considered advisable to have Miami continue the operation. The Government has an option to buy 120 million lb of refined copper from present production at market prices. Miami will develop the new ore- body at its own expense-estimated at $3 million. If losses under the new contract reach a specified point, Miami may cancel the agreement. The company plans to use the block caving method in the underground operation.

Jan 4, 1953

THE RELATION OF THE ENGINEER TO RECONSTRUCTION FIFTY-THIRD MEETING OF BOSTON SECTION The fifty-third meeting of the. Boston Section was held April 28. The speaker of the evening was the new president of the Institute, Mr. Howard V. Winchell, who spoke on "The Relation of the Engineer to Reconstruction." He told of the part engineers had played in the war and paid tribute to Herbert E. Hoover as an example of what engineers can do. He said that engineers are not taking enough interest in politics, although it is badly needed as shown by the evidences of Bolshevism even in America. Conditions have suddenly changed; whereas we formerly borrowed money we are now loaning widely to foreign countries and our investments, abroad have to be protected. A committee is badly needed to investigate and determine the actual conditions. The Government has already been invited to cooperate with the Institute along professional lines and this should lead to closer contact between our Society and the Government. Mr. Winchell then went on to describe some of the mining conditions in Russia. He brought out the point that the rich platinum deposits are exhausted and only the poorer sands remain. The largest copper properties average less than 2 per cent. copper and there are some 4,000,000 tons available in .the Caucasus region near Batum. There are approximately 100,000,000 tons of high-grade manganese ore scattered in small deposits in the eastern Ukraine. There are some copper mines in the East, butt they are almost exhausted. The Baku oil field is the second largest in the world and there is probably oil in Persia. There are also manganese in Siberia and coal veins of enormous thickness.

Jan 7, 1919

Briefly, an open stope is one in which the ore is taken out and no filling is put in; the only support for the walls may be posts or pillars of ore. Such a method is limited to orebodies with strong walls and ore strong enough to stand unsupported over the back of the stope. Details vary and depend on the dip of the vein, mode of breaking ground, method of handling broken ore, and so forth. The examples given are the Beat-son, Birmingham district, Mineville district, and Cornucopia.

Jan 1, 1925

A meeting of the New York Local Section of the American Institute of Mining Engineers, in joint session with the American Electrochemical Society, was held at the Engineering Societies Building, 29 West 39th Street, New York City, Nov. 20, 1913. Mr. Lawrence Addicks, Chairman of the American Electrochemical Society, presided at the meeting, in conjunction with Mr. Louis D. Huntoon, Chairman of the New York Local Section of the American Institute of Mining Engineers. The Chairman announced the subject to be discussed it the meeting as follows: As this is a joint meeting of the New York Sections of the Electro-chemical Society and the Institute, Mr. Huntoon has insisted that I share the responsibilities of the chair to the extent of introducing the speakers.

Jan 1, 1914

Secondary blast holes are now being pierced in quartzite and sandstone quarries, using multiple hand-operated Jet-Piercing units supplied with oxygen, fuel and water from a compact mobile carrier. A unit of this type, operating in a Canadian quarry, enabled four Jet-Piercing blowpipes to pierce blast holes for two hours without shutdown. The piercing blowpipes used were developed by Linde Air Products Co., a division of Union Carbide and Carbon Corp. The mobile supply carrier was constructed by the quarry from specifications supplied by Linde and modified by the quarry operators for their particular use. Employment of the new self-contained unit, which allows up to four operators to pierce approximately 450 ft of blast hole without shutdown, accelerates rock removal operations. Normally, only two blowpipes are in operation at one time. Large boulders or ledges, which sometimes remain after primary blasting to hamper loading operations, can, in the case of certain hard rock, be prepared for reduction more rapidly with these new units than by any other means. A special feature of the new manual Jet-Piercing unit is the mobile gas and fluid supply carrier. It consists of a standard truck chassis fitted out with four banks of large standard-capacity oxygen cylinders, a steel-holding tank for fuel oil, and a gasoline-driven air compressor and tank for pressurizing the fuel oil tank. Cooling water for the blowpipes is supplied to the unit from a hose extension to the quarry supply line. Feeder lines from the oxygen cylinder manifolds and the oil and water tanks terminate in four sets of take-off stations on the control panel at the rear of the truck. As many as four hand Jet-Piercing blowpipes can be connected to the take-off panel by high-pressure rubber hoses. The hand Jet-Piercing blowpipe used with the mobile supply carrier is a highly portable device which can be manipulated comfortably by one operator. The blowpipe can pierce blast holes at rates up to 60 ft per hour, depending on the properties of the rock. Blast holes can be pierced at any angle from the vertical to the horizontal, making it necessary for the operator to drill from the top of the boulder. Hole diameter is held to approximately that which allows the use of a standard 11/8-in. diameter dynamite. The manual Jet-Piercing blowpipe has these important design features: a burner from which the combustion gases emerge at supersonic speeds (in excess of 6000 ft per sec); a hole-sizing shell which controls the minimum size of the hole and protects the copper burner; and a sliding shield which protects the operator against the steam and spallings ejected from the hole during the piercing. The Jet piercing process has been applied successfully in United States and Canadian quarries within the last several years as an advanced method of "drilling" blast holes.

Jan 1, 1952