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By A. B. Parsons

Not so many years ago the interest of the average mining engineer in money matters-aside from his pay check or his consulting fees-was confined to the per-ton cost of mining and beneficiating ore and to the amount of capital that would be required to erect the plant necessary to carry out such operations on a prescribed scale. The so-called "business men" assumed that questions of marketing the products, of profits, and of dividends were in their exclusive sphere-matters too intricate or, perhaps, too practical for the mere engineer! In the case of a new enterprise, the promoter shouldered the entire responsibility for raising the necessary funds, and incidentally he got the lion's share of profits. In fact, he frequently profited handsomely even though the mine earned little or nothing. Occasionally the engineer turned promoter or entrepreneur--conspicuous examples are Herbert Hoover, D. C. Jackling, William Braden and F. W. Bradley- but by and large he remained in a sphere of his own. To what extent this condition of affairs has changed is difficult to say. It might be argued that it were better that it be not changed; and yet I cannot help feeling that in mine promotion lies a distinct opportunity for the

Jan 1, 1932

By Alfred V. de Forest

We are now assembled in this hall for the eighteenth lecture in honor of the memory of our greatest American metallurgist, Henry Marion Howe. Many of his most intimate contemporaries, led, as was fitting, by Professor Sauveur, have described his vital accomplishments in three fields: as a leader in technical industrial development; in theoretical research; and finally as a teacher and source of inspiration for nearly two generations of students. In 1914 Professor Howe had retired from active teaching, but maintained his laboratory at Columbia University under the care of Arthur G. Levy, with whom he published many of the papers that later were incorporated into his last book, " The Metallography of Steel and Cast Iron." My position at the time was that of personal assistant to Professor Campbell—no pay, no duties, but the great privilege of preparing specimens, taking pictures and attending to some of the current consulting work. Whenever possible, I visited Howe's laboratory to chat with Levy and gather ideas about the wonderful field of metallography—in which I was a rank amateur, rescued by the quiet enthusiasm of Donald Smith of Princeton from an instructorship in civil engineering. Levy let me act as a fly on the wall during the Professor's occasional visits. Busy as he was, Professor Howe took the time and trouble to encourage my interest, as he had done for hun- dreds of others. He told me how he went about gathering his own information speculating as to causes, considering experiments, and verifying his conclusions. I ventured to mention some tests I had run on the irregular stretching of wires of different metals. He read the small volume I had prepared of ill-assorted facts and fancies and remarked: "Nobody cares for your theories or the history of your tests. Describe what you found as briefly as possible and perhaps I can help you to publish." Curiously enough, among my discards were some autographically recorded load-versus-electrical-resistance measurements. Taken with inadequate knowledge and equipment, these curves did not reproduce consistently, but if the relationship between strain and resistance had then been explored, the latest type of strain gauge might have been in useful service for the past 25 years. Professor Howe was a gifted teacher, perhaps because he was primarily an ardent and assiduous student. His own eagerness to learn and his willingness to revise and extend his opinions constantly encouraged those of his environment to be diligent and painstaking in the pursuit of knowledge. In honoring his memory, I also wish to bring to mind the kindly, humorous and quiet Levy, and join his name again, as it was for too brief a space in the past, with that of many-sided Henry Marion Howe. Factors oF Impact Strength The subject chosen for the Howe Memorial Lecture by Dr. Gillett last year

Jan 1, 1941

By H. M. Davis, T. S. Jones

A methodfor accelerating the reduction of a metal oxide by carbon monoxide is to incorporate in the reduction system a nonreducible oxide which has a strong affinity for carbon dioxide and will remove it from the product gases. The effectiveness of this method was investigated by veduction experiments on specially prepared powder mixtures of SrO-ZnO ("active'.) and SrCO3-ZnO (reference). Measurements at 750o and 677°C showed that the rate of reduction of ZnO by CO was as much as an order of magnitude greater in the presence of SrO. Under the experimental conditions at least as much CO2 as generated by veduction was absorbed when SrO was present. Enlzancernent of the veduction rate by SvO resulted from modification of' gaseous djfitsion processes. THE specific question posed in this investigation was whether the reduction reaction CO + ZnO - Zn(g) + COa [1] could be accelerated by incorporating strontium oxide into the oxide charge undergoing reduction. Provided the strontium oxide was active enough, it could remove carbon dioxide from the product gases of ( 11 and form strontium carbonate, thus modifying Reaction [ 1] to CO + ZnO + SrO = Zn(g) + SrCO3 [ 2] This study of the comparative rates of Reactions [ I] and [2] can be considered as a particular case of a general scheme for increasing the rates of reduction of metal oxides by carbon monoxide. The limits of applicability of this scheme are indicated in the simple thermodynamic analysis presented in the appendix. This analysis primarily dictated the choice of the system, CO-ZnO-SrO, employed in this investigation. In addition, it was thought that a study of this scheme by use of the CO-ZnO-SrO reaction system would be of special interest in view of indications in the literature1-3 that the gaseous reduction of zinc oxide is prone to rate control by diffusion in the gas phase. The distinction should be pointed out between this and other efforts to increase the rates of reduction reactions through the use of addition agents. Additions of a wide range of chemicals have been tried with de- grees of apparent success varying from slightly negative to highly positive. The reasons for making additions have included the use of salts to produce effects akin to catalysis,4, 5 the alteration of the microstruc-tural details of the reduction process (including solid-state diffusion),6-8 and the conversion of an en-dothermic reaction into one that is exothermic or autogenous.9-12 The means used to attempt alteration of the enthalpy change has commonly been to incorporate lime into the charge, so that heat is generated by reaction with either of the reaction products, carbon dioxide or water. The use of lime in this way makes endeavors such as that of Edstrom and Wiberg similar to the present one. Furthermore, the basic principle behind the present work has previously been set forth.13 However, a detailed investigation of the type of reaction described in this work does not appear to have been conducted. EXPERIMENTAL PROCEDURE From both conceptual and physical standpoints, Reaction [2] is to be considered as the sum of two reactions:

Jan 1, 1968

By F. F. Aplan, G. Simkovich

Zinc oxide, an n-type semiconductor, and nickel oxide, a p-type semiconductor, were studied in electrostatic separation experiments in pure and doped forms. In addition, pure potassium chloride and potassium chloride containing one volume per cent silver were also investigated. It was found, in agreement with theory, that the presence of dopants in the oxides could either increase or decrease the electrical conductivity of the base compounds and, thus, control the response of these particles to electrostatic separation. Further, it was shown that the same dopant in the n- and p-type semiconductors produced opposite conductivity effects; again in accord with theory. Finally, it was found that the presence of dispersed silver particles in the normally insulator phase potassium chloride produced sufficient electronic conductivity to cause the silver containing particles to respond as would materials possessing "medium-type" conductivities.

Jan 1, 1980

By A. L. Holley

The three principal mines from which the celebrated Salisbury iron ores are obtained are called respectively the "Old Hill," "Davis," and "Chatfield" ore beds, and are situated in the town of Salisbury, Litchfield County, Conn., on the eastern slope of the Tocconuc range of hills.* The Old Hill Ore Bed is a tract of land of 100 acres, originally granted by the General Court in October, 1731, to be laid out by Daniel Bissell of Windsor. It mas Boon after surveyed and located by Ezekiel Ashley and John Pell. The descendants of Ashley are still proprietors in the mine. The supply of ore has been very abundant, and for many years was easily obtained, but latterly the cost of raising has been greatly increased. Up to about 1840 the average yield was estimated to be about 4500 tons per annum. The production has gradually increased until the average yield at present is estimated at 15,000 tons annually. The largest production in any one ymr was about 20,000 tons. The proprietors of this mine were incorporated many years ago under the style of " The Salisbury Ore Bed Proprietors." The Davis Ore Bed, named after an early owner, was originally called Hendricks Ore Bed, and was owned before the organization of the town of Salisbury by Thomas Lamb, one of the first settlers

Jan 1, 1879

By K. C. Hong, R. B. Jensen

The problem of determining the optimum set of steam volumes and cycle lengths for a single well undergoing multicycle steam stimulation in order to maximize the cumulative discounted net income has been formulated mathematically and programmed for a digital computer. The mathematical fonnulation of the problem and the method for its solution are discussed in this paper. The oil production performance during each stimulation cycle was simulated by either a constant percentage or a harmonic decline. Using simple analytical expressions for production performance, the cumulative discounted net income and cumulative time of operation were related to the pertinent process and cost parameters and two principal process control variables (cycle length and steam injection volume). The discrete maximum principles was used to transform the equations for cumulative time of operation and cumulative discounted net income into a set of simultaneous equations. The simultaneous equations then were solved by trial and error on a digital computer to determine the set of cycle lengths and stem injection volumes that gives maximum cumulative discounted net income over the project life. INTRODUCTION Steam stimulation is a process for improving the oil recovery rate from wells producing high-viscosity crudes. The process is applied on an individual well basis and is executed in a series of cycles, each consisting of three phases: steam injection, soaking (steam condensation), and production. Significant increases in production rate following the stimulation operation result from heating the reservoir around the wellbore. As heat is removed with produced fluids and dissipated into nonproductive formations, the production rate declines, usually to near the prestimulation value. Typical production responses are given in case histories reported by Owens and Suter,l and are depicted in Fig. 1. Duration of the production phase is equal to the time for the oil production rate to decline to some specified value and is called the cycle length. (Cycle length is defined as the producing portion of the cycle and does not include the downtime required for steam injection and soaking operations.) Termination of the production phase coincides with the start of steaming for the next cycle. The process is continued, cycle by cycle, until it becomes unprofitable. Models 2-4 have been developed to simulate behavior of a single well during one cycle of steam stimulation and have been used to investigate the effects of system and operating conditions on the production responses. However, these investigations have not shown how the models can be used to determine a most profitable set of operating conditions for a multicycle stimulation project. Perhaps these models are too complicated mathematically to be adapted readily to an optimization study. This paper presents a method for optimizing a multicycle steam stimulation project based on simple production performance models. First, the performance of a steam-stimulated well during each cycle was simulated by either a constant percentage or a harmonic decline model. Using these simple analytical expressions for production performance, the cumulative discounted net income (before tax) and cumulative time of operation for each cycle were related to the pertinent process and cost parameters and two process control variables—the cycle length and the steam injection volume. Finally, the profit function to be maximized was formed. The analogy between the above problem and problems of optimizing multistage decision processes that have been reported extensively in the chemical engineering literatures5-10 in recent years has led this investigation to the use of the discrete maximum principle.5-7 This principle was used to transform the equations for cumulative discounted net income and cumulative time of operation into a set of simultaneous equations characterizing the optimum operating conditions in terms of the two control variables. These equations

Jan 1, 1970

By Richard Hunt

BINGHAM has produced 6 per cent. of this country's copper. In total production, it ranks fourth among the copper camps of North America, the order being Butte, Michigan, Bisbee, and Bingham. In its annual production, it held that same rank until 1919, when its production was exceeded by the combined production of the Globe-Miami district of Arizona. Bingham has also been a lead camp of the first order. Utah ranks third among the lead-producing states, and its production comes largely from three camps which, in the order of their productivity, are: Bingham, Tintic, Park City. Bingham's silver production is important, but it does not rank high as a silver producer. Utah owes its rank as first among the silver-producing states to Tintic, a camp 40 miles due south of Bingham. The United States Mineral Resources reports a total production from Bingham for the period 1865-1920 having a gross value of $528,043,432. Bingham is on the eastern flank of the Oquirrh range 30 miles south-west of Salt Lake City, from which it can be reached in an hour by auto, or by the Denver & Rio Grande or the Bingham & Garfield railroads.. The automobile route is a paved road across the floor of Great Salt Lake Valley, through farming country. The Bingham & Garfield railway leaves the level of Great Salt Lake at the northern end of the Oquirrh range, and in 20 miles it climbs 2100 ft., and deposits the traveler upon a shelf cut in the side of Bingham Canyon below most of the mines, which are farther up Bingham Canyon and its tributary Carr Fork. Below lies the town, a narrow ribbon running for a couple of miles along the bottom of a canyon 2000 ft. deep-an almost impossible site for a community numbering, in prosperous times, 5000 to 7000 inhabitants drawn from all quarters of the globe. Up the canyon and down, and beneath the steep slopes nearby, and beneath the town itself, are the mining operations of over half a century.

Jan 3, 1924

By Joseph W. Siefke

Jan 1, 1985

By P. D. Merica, H. Scott, R. G. Waltenberg

The remarkable phenomena exhibited by the aluminum alloy known as duralumin were discovered during the years 1903—1911 by A. Wilm1,2 and have been described by him and by others. 3, 4,5.6 The unusual feature of this alloy is the fact, as was shown by Wilm, that it can be hardened quite appreciably by quenching from tempera-

Jan 1, 1921

B. S. and E. M. from the School of Mines at Socorro, New Mexico, in May, 1912. Immediately after graduating, he began as a practical miner in the U. S. mines at Bingham, Utah, but in November, 1912, he entered the operating department of the Chino Copper Co.'s concentrator at Hurley, New Mexico, where he stayed until July, 1913. During the latter half of 1913, he was employed as chemist in the laboratory of the El Paso smelter, at El Paso, Texas. In December, 1913, he became engineer and geologist with the Empire Zinc Co., at Socorro, New Mexico, which position he held at the time of his admission to the Institute in 1914, and until he entered the army in June, 1918. Before beginning the study of mining, Mr. Ringlund had completed a course in pharmacy, which accounts for his enlisting in the Medical Corps. Lieutenant George Roper, Jr. George Roper, Jr., a Junior Member of the Institute, was killed in an aeroplane accident near Shotwich, England, on Play 25, 1918. He was born at Steubenville, Ohio, in 1893, and at the time of his admi~sion to the Institute in 1916 was a student in mining and metallurgy at the Massachusetts Institute of Technology, Boston, Mass., from which he received the degree of S. B. in June, 1917. In August, 1917, he enlisted in the Royal Flying Corps, and after preliminary training on this side of the water, was sent to England. He was making the final cross-country flight of his course of training when the accident occurred.

Jan 1, 1920

By Benjamin N. Webber

THE peninsula of Nicoya contains virtually all of the known manganese deposits of Costa Rica. These are south and west of the Tempisque River, which flows across the peninsula near its juncture with the mainland. This peninsula forms the westernmost part of the province of Guana¬caste, which is the northern of the two Pacific Coast provinces of Costa Rica. The larger villages are connected by ox-cart roads and trails. The area may be covered on horseback without difficulty except during the rainy season, when rivers are in flood and difficult to ford. This is particularly true of the Rio Seco-Guayjiniquil area, where there are no inhabitants and few open trails through the tropical jungle. Santa Cruz and Sardinal are served by the Taca Airlines, two planes a week from San Jose and Puntarenas. The port of Puntarenas has excellent loading facilities but none are available nearer the manganese districts; there ore must be lightered to vessels standing offshore. PHYSIOGRAPHY In Costa Rica there are three physiographic divisions: (I) the central plateau (Mesa Central), a somewhat dissected lava platform upon which are superimposed volcanic peaks, some of which are still active; (2) the Atlantic lowlands and (3) the Pacific lowlands. The peninsula of Nicoya and the larger part of the province of Guanacaste lie within the Pacific low lands. The term "lowland" indicates relation to the central plateau, as the peninsula of Nicoya is largely mountainous. The mountains of Nicoya form the southern extremity of a range of low hills, which are almost continuous along the Costa Rican coast to the Nicaraguan border. The coast line shows evidence of subsidence. The Gulf of Nicoya obviously is the drowned valley of the Tempisque River. The west coast of Nicoya shows many rocks, shoals, bays, inlets and small islands as evidence of a sea encroachment. The altitude of the manganese deposits ranges from 0 to 800 ft. Topography is of the mature type of wide valleys and low ,hills, often with abrupt slopes. The climate is tropical and humid; rainfall of 125 in. falls largely between Sept. I and Jan. I. Vegetation often is very dense, the Rio Seco-Guayjiniquil area being truly tropical jungle, containing many hardwoods. HISTORY AND PRODUCTION The production of manganese ore in Costa Rica apparently dates from the first World War. It reached a peak of about 10,000 tons in the year 1919, then declined rapidly. Evidence of this period of prospecting has rotted away or been swallowed by the jungle. The war now in progress apparently revived the interest in Costa Rican manganese and has encouraged further prospecting. Deposits long known have been redenounced and trails have been cut through the jungle to them. Many new deposits have been discovered in the last

Jan 1, 1942

By I. N. Zavarine

THE present paper is a continuation of the work on the relationship between the magnetic and the phase transformations in carbon steels during quenching. An account was given by the author in a previous paper1 of an investigation of this relationship during a continuous quench. The experimental difficulties then encountered prevented a conclusive proof of the existence or absence of such a relationship. The conclusions of the previous paper were derived indirectly. The present paper deals with the same problem, but the method of attack is modified. The technique developed by Davenport and Bain2 in their well-known study of austenite transformation at subcritical temperature was adopted in the present investigation.. They have shown that the austenite to martensite transformation can be caused to proceed at a relatively slow rate by quenching steels into a hot metal bath. Slowing down of the rate of transformation, together with an observation by Lewis3 that a eutectoid steel can be preserved in the nonmagnetic state by such quenching, pointed out a possibility of a study of both transformations .under more favorable conditions than previously described. The preliminary steps were connected with the technique of the hot bath quench. To study this phase of the present work a modification of the apparatus previously described1 was used. The modification consisted in the use of a hot quenching bath instead of brine, and in fixing the secondary and the primary coils of the apparatus in a stationary position in and around the bath. Tubular specimens, as in the previous investigation, were heated in a suitable furnace to a temperature in the austenitic

Jan 1, 1935

By Harold B. Ewoldt, Robert R. Reynolds

THE Upper Mississippi Valley zinc-lead district covers an area of some 2000 sq ml located in the southwestern corner of Wisconsin, the north-western corner of Illinois and a portion of eastern Iowa around the city of Dubuque. Commercial deposits of lead and zinc have been mined in Iowa but the major discoveries during the past eight years have been made in Jo Daviess County, Ill, and LaFayette County, Wis. Activities in the state of Illinois are centered about the city of Galena, while those in Wisconsin are located a few miles south and west of the town of Shullsburg.

Jan 3, 1951

By Ralph Hultgren, Prodyot Roy

Manganese vapor pressures from 1250° to 1500°K were measured by conventional Knudsen and torsion-effusion methods in twelve Fe-Mn alloys with compositions from 9 to 80 at. pct Mn. The Knudsen re-sults agveed approximately with previous measurements found in the literature which indicated the solutions were nearly ideal. However, except for the higher manganese compositions, the initial torsion readings indicated much (up to 50 pct) higher vapor presszcres than the Knudsen method. These high readings decreased steadily with time. The results are interpreted as due to depletion of surface concentration of manganese during evaporation. Thus the initial torsion readings are the most nearly correct and Knudsen methods on alloys are to be regarded with suspicion unless it can be demonstrated that diffusion rates are rapid enough to replenish surface concentrations depleted by evaporation. For the lowest manganese contents and highest temperatures, depletion causes initial torsion readings to be too low. FEW thermodynamic data are available for alloys of the high-melting transition metals due primarily to experimental difficulties at the high temperatures involved. Measurement of vapor pressure is one of the most promising techniques to be applied to this problem. From the vapor pressure of a component of an alloy phase, its activity or its partial molar Gibbs energy can be directly calculated. From measurements over a sufficient range of temperatures and compositions the partial and integral Gibbs energies, enthalpies, and entropies may be determined through Gibbs-Duhem integration. For solid phases of variable composition, which commonly are found in alloys, measured vapor pressures are low because of depletion of the surface concentration of the more volatile component as it is selectively vaporized. Diffusion from the interior tends to restore the depleted concentration. The seriousness of the effect depends on the relative rates of diffusion and vaporization. Although depletion has been recognized as a factor,' direct measurements of its rate are lacking and quantitative estimates of its effect on measurements are uncertain. In the present work the vapor pressures above a series of Fe-Mn alloys have been measured by the torsion-effusion method. This method permits a measurement of the vapor pressure of manganese as soon as the sample comes to temperature and continuously throughout the run. The rate of decline of the apparent vapor pressure measures the rate of depletion and the torsion reading at zero time should be correct. At high manganese concentrations (70 and 80 at. pct Mn), the torsion reading remained nearly constant; surface depletion was negligible. There was a slow drop in measured pressure due to bulk loss of manganese from the sample. However, for lower manganese contents, especially at high temperatures, the depletion effect was considerable and the apparent vapor pressure decreased steadily with time. For these alloys the Knudsen method should give pressures which are too low. The measurement of pressure in the Knudsen method cannot be made until enough manganese has been vaporized to be weighable. The Knudsen result is therefore an integrated average between the initial and final vapor pressures. To verify this, conventional Knudsen measurements were also made with results in approximate agreement with previously published Knudsen measurements for these alloys. As expected, for the lower manganese contents the initial torsion readings of pressure were as much as 50 pct higher than the Knudsen. THE APPARATUS The apparatus, shown in Fig. 1, is capable of operating to temperatures up to 2000°K. A vacuum of 5 x 10"6 mm Hg can be maintained. Temperatures were measured to +3° by a W-Re thermocouple placed in the dummy cell, N. The torsion cell consisted of two alumina crucibles with holes in their covers. They were placed in the molybdenum holder shown suspended from the torsion wire. Rectangular torsion wires (1 by 4 mm) were found to have superior sensitivity and less residual distortion than circular (2-mm-diameter) wires. The precision of angular measurement was found to be *0.025 deg; the variation is no doubt due to temperature fluctuation and vibration. For the Knudsen experiments the alumina cell was set on the support, N. SAMPLE PREPARATION 800-g samples were prepared by melting together electrolytic iron and electrolytic manganese and pouring the melt into a water-cooled copper mold. Melting and pouring were done under a helium at-

Jan 1, 1965

By E. A. Gulbransen, W. S. Wysong, K. Andrew

The reaction of carbon in solid solution in a metal with the surface oxide fim on many metals may be inferred from thermo-dynamic calculations for high vacua and high temperature conditions. Holm has recently shown that oxide films may be removed from ferrous materials by heating in a vacuum at high temperatures and that carbon is the essential element in the reaction. considerable work has been described in the literature on the de-carburization reaction. Several general references may been 2,3,4 However, the nature of the mechanism involved in the decarburization is not well understood. Our interest in this reaction resulted from many attempts to degas and to reduce by pure and dry hydrogen the surface oxides on strips of various types Of chrome-nickel alloys. Some of the early experiments On the behavior Of '3 pct chrome-iron in vacua of the order of 5 X lo' mm and at a temperature Of 600°C have been reported.5 These experi-merits showed a 'low reaction with the residual Oxygen Or water vapor in the system and no reaction with hydrogen. This is in accord with thermodynamic data which would lead to the prediction that it is extremely difficult to maintain a hydrogen atmosphere at 600' C pure enough to reduce Crz03 formed On the surface. The crystal structure of the superficial oxide film formed on 13 pct chrome- iron and Nichrome V has been investigated in the thin film range by Gulbransenr Phelps and Hickman,' and shown to be "203. It Was surprising to us to note that when a specimen of Nichrome V containing approximately 80 pet nicke1 and 20 pet chromium was heated to 850°C in a high vacuum, the specimen lost weight. The rate Of weight loss was very temperature sensitive. A study of this reaction in vacua and in a hydrogen atmosphere is the subject of this communication. Type Reactions Let us consider the various reactions which may occur when a metal is heated in vacua, in a hydrogen atmosphere, or in an oxygen atmosphere. The number and kind of reactions will depend upon the chemical nature of the metal, its alloying constituents and the location of the alloying constituents. The metals used in this study are chrome-nickel alloys of the heater type, They consist essentially of chromium, nickel and iron, small amounts of carbon, silicon and manganese and traces of zirconium, calcium, aluminum and magnesium. The trace elements are added to improve the lifetime and other characteristics of the alloy when used as a heater. Seven of the more important reactions with which we are going to be concerned here are as follows: 1. Metal . (gas) F? metal + gas — degassing of the metal 2. zM(s) + y }i Oi(g) M MIOu(s) -oxidation

Jan 1, 1949

By J. Goldfield

Asbestos fiber, before it can be used commercially, is separated from the rock in which it is naturally found. Johns-Manville Corp. is currently constructing a 12-story fiber mill, of which the first half is completed and in operation. The mill will be the largest in the world, producing about 30 pct of the world's fiber. It was engineered and constructed by a cooperative effort of the engineers of the Canadian Johns-Manville Fibre Div. and the general plant engineering dept. Detailed design work on all phases of the job was done by Surveyer, Ninniger & Chenevert of Montreal. A series of crushing, screening, air aspirating and air separating processes will separate the fiber from 10 tons of rock per min. But to process this amount of ore about 90 tons of air per min will be handled in the aspirating and dust-collecting systems. To express this in more common units, 2.5 million cfm of air will be required. All this air will pass through a bag-type continuous automatic filter and will be expelled to atmosphere in summer or returned to the mill for heating during the winter months.

Nov 1, 1955

The following letter has been received from Prof. Alfred C. Lane, of Tufts College, who is now in charge of the department, of mining in the College of Engineering, American E. F. University, Beaune, France. My DEAR MR. STOUGHTON: I have had a very interesting time here. We were received fast Saturday with great courtesy by the Schneiders at the Creusot plant, and saw many interesting things, from the mammoth guns clown. In one trip I saw a coal mine, an iron mine, an oilshale mine, a gypsum mine, and a most beautiful fluorspar mine. So you see we were not badly located. A mine like Epinac, which has a washery, a briquetting plant, and great central electric plant where coal that might otherwise be waste is converted into electricity and shipped away at 30,000 volts pressure, is of interest mechanically as well as geologically. Many of the French coal seams are very thick here and have especial mining methods. The Department of Mining has been manned by men with whom it was a pleasure and an honor to be associated, as well as with Dean Reber who was in charge of the College of Engineering as a whole. Names like Captain H. C. Ray, former professor at the University of Pittsburgh, on leave in the army, Captain Archbald of the Colliery Engineer at one time, whose work in the Pennsylvania coal mines is well known, Captain Vail of the Engineering and Mining Journal staff and Captain E. C. Dietrich of the Southwest, are familiar to members of the Institute, and Are guarantees of competent instruction.

Jan 7, 1919

By H. De Cizancourt

The Pechelbronn (Alsace) field is the only important French producing field. During 1934, development was carried on as in previous years. The total output of this field reached 553,575 bbl. in 1934, showing a slight decrease from the 1933 figures. Of the total, 315,000 bbl. (56 per cent) was extracted by drilling, while 238,875 bbl. (46 per cent) was obtained by means of shafts and galleries. Exploration of deep Jurassic and Triassic horizons was still in progress at the end of 1934. A deep well reached the Upper Triassic at a depth of 34 m. (2736 ft.). (Information kindly supplied by M. S. Mena, Directeur Technique.) As mentioned before, the small Gabian field (Herault) is gradually being exhausted. No drilling operations were undertaken in 1934, the small production being restricted to the pumping of old wells. Two exploration wells, noted as "drilling" at the end of 1933, were completed in 1934; viz., Lavelanet (Ariége) at 3785 ft. and Santenay (Niévre) at 2578 feet. French Possessions Algeria.—No drilling at Tliouanet. Out of a total of 100 wells drilled in the area, only 8 are still producing. No exploration work is reported during 1934 in Algeria. Tunisia.—Two wells completed; one well drilling at the end of 1934. A total of 11 wells is reported to have been drilled before the beginning of 1935; out of these, 8 were completed before the present program was begun. Morocco.—Exploration work progressed actively last year. The outstanding event was the coming in of Ts. 26 well at 1243 ft. This well took fire, therefore great difficulties were encountered in the accurate measurement of initial production; the figure of 1500 bbl. of oil given here is a near estimate. Oil flowed accompanied by a great amount of water. The apparent decrease of drilling operations in 1934 is explained by the increase in field activities after the results of Ts. 26 were known;

Jan 1, 1935

CARL E. SWARTZ, Chairman D. K. CRAMPTON, Past-Chairman CYRIL S. SMITH, Vice-Chairman ARTHUR PHILLIPS, Vice-Chairman FRANK T. SISCO, Secretary 29 West 39th Street, New York, N. Y. H. A. MALONEY, Treasurer Executive Committee 1943 1944 ERIC R. JETTE WILLIAM C. ELLIS LOUIS W. KEMPF ALAN MORRIS GEORGE SACHS KENT R. VAN HORN

Jan 1, 1942

By K. Sassa, I. Ito

The dynamic principal stresses induced within rock by an explosion under con fined conditions are analyzed for the case of blasting with one free face by applying the values of measured radial displacement, particle velocity and so on to equations derived from the theory of elasticity. The dynamic stresses on the free face are also calculated from the strain measured by wire strain gauges affixed on the free face. Some results obtained are briefly: 1) The maximum stress on the free face appeared at the intersection between the free face and the burden, and its magnitude was about twice as large as the magnitude of the tangential tensile stress imparted by the incident stress wave within the range related to the breakage by blasting. 2) The maximum value of the compressive stress near the free face was decreased due to the existence of the free face, while that of the tensile stress was increased. 3) At any point near the free face, the directions of the principal stresses in the r? plane using spherical coordinates with the origin at the center of the spherical charge, changed with time except in the direction of the burden. However, at another point near the explosion point where the principal stresses were mainly those stresses caused by the initial longitudinal wave, the directions of the principal stresses coincided with those of the coordinate used. 4) The maximum value of the tensile stress in the F direction was larger than those in the re plane at and near the free face. 5) The tensile stress caused by the Hopkinson effect appeared only near the burden. 6) It is presumed from the results of stress analysis that radial cracks will be produced in the rock mass near an explosion point, but with the approach of the free face, the directions of cracks curve towards a direction parallel to the free face. INTRODUCTION In order to investigate the mechanism of rock breakage by blasting, it is considered to be very im- portant to know how the stresses are generated and distributed within the rock by explosion of a confined charge. As part of a research program concerning the mechanism of rock breakage by blasting, the authors have already published papers on the detonation pressure produced at the inner surface of the charge hole1 and on the behavior of the dynamic stresses within rock caused by an explosion in the case where no free face existed.' In this study the dynamic stresses on and near the free face have been investigated for the case of blasting with one free face. The mechanism of rock breakage in blasting is discussed in the light of these studies.

Jan 1, 1967