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By E. R. Johnson

The copper concentrator of the Braden Copper Co. is at Sewell, Chile, on the westem flank of the main Cordillera of the Andes, at an air distance of approximately 50 miles southeast of Santiago, the capital of Chile. The region is mountainous and space is at a premium because of the rough terrain and the danger of snowslides. The ore, a porphyry copper, is mined by a block-caving method in the El Teniente mine. It is hauled to the crushing plant, a distance of 2.6 miles, through a tunnel because of the severe climatic conditions. The usual large, coarsely set, primary reduction machines found in many ore-treating plants are not required because of the mining method employed and the limiting 12-in. spacing of the grizzlies at the head of each ore pass in the mine. It is the purpose of this paper to describe the numerous improvements made in the crushing section of this large flotation concentrator during the past I5 years to increase the efficiency of the plant and to raise the daily output from around 20,000 to 30,000 tons. The reader should keep in mind that all changes were made within the existing building because of the limited space and the high cost of the heavy mill construction required to withstand the snow loads. The present plant, as well as the former, operates on a 24-hr, 7 days a week basis. The crushing plant commenced operations at its present site in 1921, the main equipment being No. 7½ gyratories, followed by 48-in. horizontal Symons disk crushers. Fines were removed by I-in. stationary grizzlies ahead of each unit. In 1924 a third stage of crushing was provided by the addition of 55½-in. rolls in open circuit. During 1925, the Symons disks were replaced by 73½-in. rolls. All the rolls were changed to closed circuit, with elevators and screens to give a final product of 9 pct plus 3-mesh. The flowsheet of a typical crushing section of this period is shown in Fig I. The ore was withdrawn from a common bill serving the five crushing sections in the plant by means of any number up to six 36-in. wide-apron feeders, which discharged onto a common conveyor belt. This conveyor was equipped with a magnetic head pulley and the crusher attendant was stationed near the discharge end to pick out pieces of mine timber that might be in the ore. The ore was discharged over a 13/4-in. spaced bar grizzly and the oversize of this grizzly was crushed by a No. 7½ McCully gyratory crusher set at 13/4-in. opening on the closed side. The grizzly undersize joined the gyratory discharge and was conveyed to a set of 73½ by 20-in. Garfield rolls set at I in. These rolls operated in closed circuit with a bucket elevator and two vibrating screens placed in parallel.

Jan 1, 1949

By Gligorije Stankovic

This paper describes the fluo-solids roaster and acid plants at the new 40,000-TPY Trepca electrolytic zinc plant. The electrolytic zinc plant units were constructed to the design of Singmaster and Breyer, New York and began operation in mid-1967. The fluo-solids roaster plant, constructed according to the design of Dorr-Oliver, Paris, includes concentrate handling and storage facilities; two independent concentrate roasting circuits, each with a 110 to 155 TPD fluo-solids roaster; waste heat boilers; cyclones; electrostatic precipitators; calcine coolers; and calcine conveyors. The acid plant uses the "Petersen system" contact process. The plant has one acid circuit with a capacity of 230 tons of monohydrate per day. Gases for the acid plant are obtained from roasting zinc concentrates. When the roaster plant is operating at maximum capacity, excess SO2 is used in two other Petersen System circuits in the near vicinity.

Jan 1, 1970

By Frank C. Greene

The year 1941 was uneventful in oil and gas development in Missouri. No new pools were opened and several areas with promising structures, in the northwestern part of the state, were disappointing when drilled. In looking for an explanation of these failures, it is suggested that it will be necessary to find areas in which the lower beds of the Mississippian are upfolded, in order to obtain production in northwestern Missouri. To do this, geophysical exploration or test drilling far enough into the Mississippian beds to get cores or cuttings of definitely established age appear to be the best methods. Although not leading to new production, drilling in Missouri established two new state records, one for depth and another for the amount of rotary drilling. An important well† in sec. 24, T. 19 N., R. 11 E., Pemiscot County, in the southeastern corner of the state, was drilled with a rotary to 4740 ft., several hundred feet deeper than any previous hole. The total footage drilled by rotary rigs of various types was 31,135 ft. and that by cable tools, 29,166 feet. The total number of completions was 85, of which 18 were gas wells with an initial open-flow capacity of 12,528,000 cu. ft., and 67 were dry holes. Of the latter, 19 were drilled into Mississippian or older formations. Table I gives a summary of activities by counties.

Jan 1, 1942

By Frank C. Greene

The year 1941 was uneventful in oil and gas development in Missouri. No new pools were opened and several areas with promising structures, in the northwestern part of the state, were disappointing when drilled. In looking for an explanation of these failures, it is suggested that it will be necessary to find areas in which the lower beds of the Mississippian are upfolded, in order to obtain production in northwestern Missouri. To do this, geophysical exploration or test drilling far enough into the Mississippian beds to get cores or cuttings of definitely established age appear to be the best methods. Although not leading to new production, drilling in Missouri established two new state records, one for depth and another for the amount of rotary drilling. An important well† in sec. 24, T. 19 N., R. 11 E., Pemiscot County, in the southeastern corner of the state, was drilled with a rotary to 4740 ft., several hundred feet deeper than any previous hole. The total footage drilled by rotary rigs of various types was 31,135 ft. and that by cable tools, 29,166 feet. The total number of completions was 85, of which 18 were gas wells with an initial open-flow capacity of 12,528,000 cu. ft., and 67 were dry holes. Of the latter, 19 were drilled into Mississippian or older formations. Table I gives a summary of activities by counties.

Jan 1, 1942

Greater automation of facilities is probably the best hope of the mining industry in its efforts to surmount continually rising labor costs. Underground mining, with its inherently low unit labor output, is especially vulnerable to rising costs, and here maximum automation is becoming increasingly important. One area of such operations that has been receiving a great deal of investigation is that of ore haulage and hoisting, two steps that often account for 10-35% of underground operating costs. Innovations and experimentation by mining firms and manufacturers over the past few years have resulted in larger, faster and more efficient tramming and hoisting equipment, but the White Pine Copper Co., at its operation in the Upper Peninsula of Michigan, is preparing to start up an entirely new concept in haulage later this summer. Known as the Dashaveyor System, it consists of individually powered modules (cars) that run on tracks inside a rectangular tube or on an open trackway at predetermined speeds up to 50 mph. At White Pine the Dashaveyor will be used to carry ore (crushed underground to -10 in.) from the mine to the concentrator. Dr. James Boyd, president of Copper Range Co., which is a 25% shareholder in The Dashaveyor Co., has indicated that if the Dashaveyor meets the expectations for surface operation, it will also be used underground for ore transport in place of the several miles of conveyor belts currently in use (Business Week, July 29, 1967).

Jan 7, 1968

The following members were appointed on the Committee Advisory to the U. S. Bureau of Standards: Arthur S. Dwight (Lead). John Fairfield Thompson (Nickel). The reports of the Committee in charge of the Arizona Meeting and the Committee on Transportation to the Arizona Meeting were accepted with the thanks of the Board. The By-Laws of the Nevada Section of the Institute were approved. The subscription price of the Bulletin to non-members of the Institute was increased to $12, per year beginning with January, 1917. This increase does not affect the reduced price of $5 on extra copies of the Bulletin which are sold to members, libraries and sister societies.

Jan 7, 1916

By Tom Westgarth

As papers are placed before you upon large gas-engines in Belgium and Germany, it was considered that some information should be given upon the same subject in Great Britain. I therefore agreed to compile these notes, which I have made very short in view of the somewhat full nature of the other papers presented to this meeting, and considering the complete nature of the many publications which have been made recently upon the subject of large gas-engines. I give below Tables I. to VI., showing the number and particulars of large gas-engines which have been built or are building by British makers, and in view of the growing size of gas-engines I have concluded that engines of less than 500 h.p. cannot now he included in the category of large gas-engines, and therefore I have not considered engines under that power. Table I.—-" Oechelhauser " Type Gas-Engines. Built or Building by William Beardmore Co., Limited, Glasgow Indicated ! Engines. Horse-Power Type. Nature of Work. Gas Used. 6 2,500 Twin cylinder. Dynamo. Producer. 1 in Single cylinder. Rolling-mill. Producer. 4 1,250 Twin cylinder. Dynamo. Producer. 2 1,250 Single cylinder. Dynamo. Producer. 4 625 Single cylinder. Dynamo. Producer. 1 625 Single cylinder. Rolling-mill. Producer. 1 625 Single cylinder. Air compressor. Producer. 2 500 Single cylinder. Air compressor. Producer. 7 500 Single cylinder. Cement-mill driving Producer. Total, 28 engines ; 32,600 indicated horse-power. * Presented at the Joint Meeting of the Iron and Steel Institute and the American Institute of Mining Engineers, London, July, 1906, and here published under a mutual agreement between the Councils of the two Institutes.

Jan 1, 1907

By Radoslav Despotovic

The developed radiometric method of particle system analysis has been applied to investigate the bulk properties of particles precipitated from solutions. The nature and principles of the method applied are described briefly, and some possible models in the field of fine colloid particles precipitation discussed. Changes in radionuclide distribution were followed during the solid phase formation and the data were used to calculate changes in bulk composition of colloid precipitates. The radiometric data show interesting phenomena closely connected with the characteristic of bulk particles. The measured radiometric data are highly reproducible, the applied methods have proved to be sensitive, and the developed techniques have been tested by various standard procedures.

Jan 1, 1980

By M. T. Worley

This paper reports investigative work conducted to develop a method of estimating the groundwater influx from a homogeneous permeable formation into a vertical mine shaft during sinking. A method of analysis was developed using data obtained from pumping tests and a modification of the Theis non-equilibrium interpretation technique. Excess influx of groundwater into mine shafts has long been one of the more important problems encountered in the development of a mining property. Much work has been done on methods of preventing such influx and on pumping schemes to control inflow if preventive measures fail. The fundamental aspects of the problem, on the other hand, seem to have been neglected. The purpose of this paper is to review the fundamentals of groundwater flow and to propose a rapid method of analyzing hydrologic data in order to estimate influx from a homogeneous permeable formation into a mine shaft. Such an estimate of the quantity of water to be encountered is of value in planning grouting, pumping and other programs designed to control that influx. It is emphasized that the proposed method of analysis should be regarded only as a tool to be used in evaluating the problem before investing the capital necessary to begin development of a property. FUNDAMENTALS OF GROUNDWATER FLOW In order to effectively approach the problem of estimating influx into a mine shaft, a knowledge of the fundamentals of fluid flow through a porous medium is necessary. Darcy, in 1856, developed an empirical relationship to explain the flow of water through sand filters. This relationship V = k (dh/dl), is the basis for all other flow formulae. It has been shown that Darcy's relation is a solution of the Laplace equation and thus is analagous to other natural phenomena such as heat flow. Theis, using the analogy of heat flow by conduction, developed an expression for determining the transient or time-dependent groundwater flow through a homogeneous, isotropic medium. The resulting equation Was also derived by Jacob using hydrologic considerations alone.' The individual terms in the equation are described in Table I. It is important to understand the assumptions upon which this equation is based. 1) The medium through which the fluid flows is infinite in areal extent, homogeneous and isotropic. 2) The well into which the fluid discharges completely penetrates the medium. 3) The characteristics of the medium remain constant at all times. 4) The initial pressure surface is horizontal. 5) The confining media are impervious and horizontal. 6) Fluid is removed from storage instantaneously by a decline in pressure. 7) The diameter of the discharge well is infinitesimal with respect to the drainage radius of the medium.

Jan 1, 1962

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Member, mining engineer, technical education, married, 15 years' experience as foreman, superintendent, manager of examination and exploration work. Prefers Pacific Coast or Alaska, but will go anywhere. Available Nov. 25. No. 422. Mine manager or mill superintendent. U. S. A., Canada or Mexico preferred. Age, 33. Member. Five years mill superintendent, mills up to 2500 tons a day-gold, silver and lead; 6 years mining from bottom up to manager. No. 423. Member, mining engineer, technical graduate, age 40, 17 years' experience, having filled every position at a mine; superintendent of large mine at present. Familiar with all kinds of mining machinery. 'Best of reference. Available after Jan. 1, 1918. No. 424. Member, age 41, with 20 years' experience in design construction and operation of mining and smelting works and steam, electric and water-power plants, etc., who has held positions of responsibility in important concerns, desires a position requiring executive or engineering ability, or both. No. 425. Member, age 37, graduate mining engineer, with 29 years' experience in all phases of anthracite and bituminous mining, at present engaged as manager of one bituminous mine and consulting engineer for others, desires position as manager of a coal mine or consulting engineer for banking interests. No. 426.

Jan 1, 1918

By William E. Ford, Edward Salisbury Dana

The Silicates are m part strictly anhydrous, in part hydrous, as the zeolites and the amorphous clays, etc. Furthermore, a large number of the silicates yield more or less water upon ignition, and in many cases it is known that they are, therefore, to be regarded as basic (or acid) silicates. The line, however, between the strictly anhydrous and hydrous silicates cannot be sharply drawn, since with many species which yield water upon ignition the part played by the elements forming the water is as yet uncertain. Furthermore, in the cases of several groups, the strict arrangement must be deviated from, since the relation of the species is best exhibited by introducing the related hydrous species immediately after the others. This chapter closes with a section including the Titanates, Silico-titanates, Titano-niobates, etc., which connect the Silicates with the Niobates and Tantalates. Some Titanates have already been included among the Oxides.

Jan 1, 1922

Engineering Council has been elected to membership in the Chamber of Commerce of the United States. Its representative will be Mr. Harold W. Buck, of Viele, Blackwell & Buck, Consulting Engineers, New York City, Past-president of the American Institute of Electrical Engineers, his alternate being Mr. Irving E. Moultrop, of the Edison Electric Illum-inating Co., Boston, member of American Society of Mechanical Engin-eers and American Institute of Electrical Engineers. The Chamber of Commerce of the United States was formed in 1912 and now consists of more than 1100 organizations in every state of the union, in the out-lying possessions, and of all the principal American chambers of commerce abroad. One of the chief aims is to obtain the best business thought on national questions that concern business. Members of the National Chamber have the privilege of using all the facilities of the Chamber's offices in Washington when information is desired.

Jan 12, 1919

By T. F. Adams, D. P. Morse

Tunneling is primarily an excavating cycle consisting of a sequence of operations: drilling, shooting, ventilating, mucking, and erecting supports, if necessary. However, the type and condition of the ground that is being worked, as well as the size and shape of the tunnel, determine the rate of advance. In addition developments in drilling, ventilation, mucking, and haulage equipment have contributed to faster tunneling. Geology: This discussion will be limited primarily to rock tunnels or those which require the use of explosives, and the cost and hazards depend primarily on the condition of the rock which may be broken, decomposed, and contain water with gas. Advance geological study is an important part of any tunnel work and helps to minimize serious miscalculations. The geology itself, at best, is a matter of experience and prediction and it is not so much a matter of the types of rock the tunnel may go through, but a knowledge of the class and intensity of the rock defects that may be encountered.

Jan 4, 1958

By I. W. Walling, F. B. Plummer

Bastin and others have demonstrated the presence of sulphate-reducing bacteria in oil wells producing salt water. Analyses show that at 125°F. bacteria alone reduce sulphates in East Texas salt water by only 3 per cent in 30 days, forming principally hydrogen sulphide and sodium or calcium hydroxide. The hydrogen sulphide reacts with soluble iron compounds to produce iron sulphide in the absence of oxygen, and ferric hydroxide where oxygen and air are present. Where iron or other metals and iron sulphide are already in the water containing bacteria, I00 per cent reduction of the sulphates is complete in 30 days or less; where magnesium is present, reduction is complete in 15 days. The effects of changes in temperature, of different bactericides, and of concentration of bactericides on sulphate reduction are described in detail and illustrated by tables and curves. The significance of sulphate reduction on corrosive properties of oil-field water is briefly discussed. Chemistry of East Texas Oil-field Water The chemical composition of the water in the East Texas field salt-water disposal pits is shown in Table I. This salt water corrodes pipes, pumps, and steel tanks excessively, principally because of its content of oxygen, hydrogen, sulphide, and carbonic acid. The carbonates in the water when exposed to air tend to give up carbon dioxide and to precipitate calcium carbonate in large quantities. This forms coatings in tanks, settling pits, and ditches, and soon, unless removed by acid treatment, will effectively clog an injection well and reduce the flow of water back into the ground. The iron compounds in the water, most of which are dissolved from tanks and pipes, are in the ferrous form, and when exposed to the air are oxidized from soluble ferrous carbonate to insoluble ferric hydroxide, resulting in the precipitation of a gelatinous precipitate that will clog oil-field sands effectively: 2Fe(HCO3)2 + O + H2O -> 2Fe(OH)3 + 4CO2 The sulphates in strong sulphate-bearing water may be attacked by swarms of sulphate-reducing bacteria and more hydrogen sulphide may be produced. The hydrogen sulphide reacts with soluble minerals in the water to form black sludges. A knowledge of the chemistry of each reaction in oil-field water is important to the oil-field engineer, since means must be devised to prevent the formation of harmful precipitates that clog injection wells and to prevent corrosion of tanks by harmful products of biochemical processes. Methods of Treating Water before Injection into Ground* The open system of handling the waste salt water in the East Texas field consists of aerating and chemically treating the water to precipitate the unstable iron,

Jan 1, 1946

By F. B. Plummer, I. W. Walling

Bastin and others have demonstrated the presence of sulphate-reducing bacteria in oil wells producing salt water. Analyses show that at 125°F. bacteria alone reduce sulphates in East Texas salt water by only 3 per cent in 30 days, forming principally hydrogen sulphide and sodium or calcium hydroxide. The hydrogen sulphide reacts with soluble iron compounds to produce iron sulphide in the absence of oxygen, and ferric hydroxide where oxygen and air are present. Where iron or other metals and iron sulphide are already in the water containing bacteria, I00 per cent reduction of the sulphates is complete in 30 days or less; where magnesium is present, reduction is complete in 15 days. The effects of changes in temperature, of different bactericides, and of concentration of bactericides on sulphate reduction are described in detail and illustrated by tables and curves. The significance of sulphate reduction on corrosive properties of oil-field water is briefly discussed. Chemistry of East Texas Oil-field Water The chemical composition of the water in the East Texas field salt-water disposal pits is shown in Table I. This salt water corrodes pipes, pumps, and steel tanks excessively, principally because of its content of oxygen, hydrogen, sulphide, and carbonic acid. The carbonates in the water when exposed to air tend to give up carbon dioxide and to precipitate calcium carbonate in large quantities. This forms coatings in tanks, settling pits, and ditches, and soon, unless removed by acid treatment, will effectively clog an injection well and reduce the flow of water back into the ground. The iron compounds in the water, most of which are dissolved from tanks and pipes, are in the ferrous form, and when exposed to the air are oxidized from soluble ferrous carbonate to insoluble ferric hydroxide, resulting in the precipitation of a gelatinous precipitate that will clog oil-field sands effectively: 2Fe(HCO3)2 + O + H2O -> 2Fe(OH)3 + 4CO2 The sulphates in strong sulphate-bearing water may be attacked by swarms of sulphate-reducing bacteria and more hydrogen sulphide may be produced. The hydrogen sulphide reacts with soluble minerals in the water to form black sludges. A knowledge of the chemistry of each reaction in oil-field water is important to the oil-field engineer, since means must be devised to prevent the formation of harmful precipitates that clog injection wells and to prevent corrosion of tanks by harmful products of biochemical processes. Methods of Treating Water before Injection into Ground* The open system of handling the waste salt water in the East Texas field consists of aerating and chemically treating the water to precipitate the unstable iron,

Jan 1, 1946

By Clifton W. Livingston

So many factors influence blasting results that theories and rules are usually dismissed as impractical; the practice prevailing today is arrived at by cut and try. Usually the first step is to experiment with drillhole patterns and spacing until an arrangement is found that gives best results. The next step is to experiment with different types of explosives and sequences of blasting until the most satisfactory degree of fragmentation is achieved and until no further reduction in cost is immediately apparent. Improved fragmentation is generally attributed to the type of powder used, the sequence in which the holes are blasted, or the use of millisecond delays. Various types of drill rounds have been evolved in tunneling operations, underground development headings, and stoping, and various patterns of blasting in open pit mines and quarries. These practices usually are carried from mine to mine or from district to district, and great skill is exercised by those experienced in the art of blasting.

Jan 1, 1960

By J. H. Henderson, L. A. Wilson, R. L. Gergins, R. J. Wygal, D. W. Reed

This paper presents a method of predicting the production history of an underground combustion recovery process. A rigorous solution of the thermodynamics and hydrodynamics involved is beyond the scope of this report. However, a practical scheme to appraise combustion recovery performance has been Worked out. By prudent assumptions, regarding the attainment of steady-state conditions, a trial-and-error solution, which satisfies both material balance and three-phase relative permeability requirements has been evolved and tested. As a combustion zone moves through a formation the interstitial water, the water of combustion and a portion of the oil wil1 be vaporized. These vapors will move downstream to a cooler region of the formation where they will condense. Part of the remaining oil will be displaced by the imposed gas drive and what remains behind will be consumed as fuel. The fluids will distribute themselves downstrean? in a manner which will satisfy the three-phase relative permeability characteristics of the formation. Three distinct zones will exist ahead of the combustion zone: (I) a zone termed a water bank which contains three mobile phases, oil, water and gas; (2) a region containing two mobile phases, oil and gas, called the oil bank; and (3) a zone having the fluid saturution distribution which existed prior to combustion. The mobile water will impose a water flood on the oil in the region containing three flowing phases. The process can be visualized as a simultaneous water .flood and combustion-supported gas drive. It is possible to estimate the saturation distributions in the water bank and oil bank as well as the production history for any combustion temperuture if the porosity, three-phase relative permeability characteristics, oil viscosity and initial saturations are known. This has been done for injection pressures ranging from I to 100 atm, oil viscosities of 10 to 1,000 cp and porosities from 20 to 40 per cent. Several of these calculations have been checked in the laboratory, with the result indicating rather good agreement between the predicted and observed production histories. The analytical and experimental techniques are described and the comparison of predicted and observed performance presented. INTRODUCTION Considerable research by the oil industry during the past 10 years has been directed toward the thermal recovery of crude oil. Of all schemes considered, the one receiving the most attention is in situ combustion. This is a process in which part of the oil is actually burned within the reservoir rock. The uniqueness of the process lies in its potential. Theoretically, this potential generates from the following: (1) it may open the door to vast reserves previously not economically producible, (2) it may induce increased production rates where low rates are now realized and (3) it may give high over-all recovery efficiency. The general idea of the process has received considerable attention in the literature '-' and the following brief description is intended for orientation only. In situ combustion can be visualized by considering a linear system, one end of which represents the injection well and the other the producing well. The formation at the inlet end is raised to ignition temperature by placing a gas or electric heater at the face of the formation or by the ignition of thermite, charcoal or similar material. While heating, the water and part of the oil in the heated region is vaporized and moved out into the reservoir by the injection of gas containing oxygen. In addition, part of the oil is displaced as liquid by the imposed gas drive. The oil not displaced is modified to an immobile, coke-like material (hereafter referred to as coke) by the high temperatures existing immediately ahead of the combustion zone. This coke is used as fuel, and the combustion front advances through the formation at a temperature which is probably in excess of 800°F. As the combustion front advancek it will drive ahead all interstitial oil not rendered immobile and all interstitial water plus the water formed by the combustion of hydrogen. As a result the sand behind the combustion zone is freed of all oil and water. Although the general description of the process has been outlined in the literature, there has been no consideration of the behavior of the fluids moving downstream from the combustion front. It is the purpose of this paper to present a technique

By M. B. Ramachandra Roa

This paper records the results of the earth resistivity surveys made in the Godavari River in connection with the Ramapadasagar project. After describing the topographical and geological features of the area, the results of the investigation at the several sites have been mentioned. Further, a detailed account has been given of the resistivity methods adopted, the apparatus used and the interpretation of the curves. The resistivity measurements carried out over the water course have been specially outlined, and a review of the verification of the electrical indications by drilling in a number of cases, has also been presented. Introduction The Government of Madras has under consideration the Ramapadasagar project which is estimated to cost some Rs.660,-000,000 (about two hundred million dollars). The most essential feature of this project is the construction of a high dam across the Godavari near Polavaram for impounding the waters of this great river of South India, whose maximum discharge is 2 million cu secs in flood time. It is estimated that when the proposed reservoir is constructed, about one million tons of rice could be produced annually under irrigation. To those who have had any acquaintance at all with the recent distressing famine conditions which India has passed through and is still undergoing, the Lounteous effects which this project will bring about to the country in the future, are obvious. In the region of the proposed reservoir, the river flows for several miles through a hilly tract, hemmed in between flanks of hard, solid rock; but the river bed is mostly sandy. A few bore holes put down in this sandy bed touched rock at a depth of 180 to 200 ft. The river bed is about jo ft above the mean sea level (m.s.l.) and the bedrock was found at —125 to —160 ft m.s.l. The crest of the dam is proposed at +162 ft m.s.l. The proposed dam mould therefore be about 120 to 130 ft above the river bed, and the foundations would have to reach down nearly zoo ft below the bed at the deepest part. A number of alternative sites were proposed for investigation, and it became necessary to quickly ascertain the bedrock topography at these sites. Dr. M. S. Krishnan,* who was consulted in the matter, furnished a detailed account of the geological features of the region and suggested a geophysical investigation which the writer carried out from February to April 1944, employing solely the electrical resistivity methods. The total length of the survey lines for the electrical measurements amounted to 62,600 ft and the number of resistivity determinations was about 2500. Altogether nine alignments for the dam were inten-

Jan 1, 1949

By Fred P. Peters

T. D. Yensen.*—As my information is of a negative nature, I think it belongs under this paper. We are particularly interested in magnetic materials and we would like very much on occasions to make use of powder metallurgy. We have tried repeatedly to use powder metallurgy in preparing our nickel alloys but always. with negative results; that is, we cannot get as good magnetic properties by powder metallurgy as we can by starting with a molten material. We have tried by all possible means to make materials' like 50 per cent iron-nickel alloys by powder metallurgy. The compacts can be regularly lorged and rolled but no matter what we do in the way of annealing, the magnetic properties come out very much poorer than if we start with molten material. F. V. Lenel. †—I want to mention one characteristic of articles made from metal powders which distinguishes them from die castings; that is, their wear resistance. Die castings usually are made from zinc or aluminum alloys and a few copper-zinc alloys; all of them are comparatively soft and not very wear resistant. I know of a number of cases where powder metallurgy rather than the die-casting method was used for producing a certain part because higher wear resistance was needed than could be attained in die castings. A, J. LanghammeR.*—The subject of powder metallurgy is somewhat difficult to discuss, and portray, in the time that his been allotted. Most of you would rightly be bored if we went into details. However, I will cite one incident that possibly will help illustrate some of the potentials. Last summer I was in Washington and met Navy officials for the purpose of studying the possibility of making a certain part by powder metallurgy. The part is highly intricate and I happened to remark that the material cost would be high; that is, the cost on one raw material. Promptly a high-ranking Navy officer said: "Mr. Langhammer, if you must pay x dollars a pound for the raw material, but achieve the desired results, the cost of the finished part would still be low."

Jan 1, 1945

By R. C. Earlougher

Jan 1, 1970