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By Gerard Matthes

WITHIN the last three years, aerial mapping has made wonderful progress. Its three sources of development in North America may be enumerated as follows: (1) The work of the U. S. Army Air. Service and Corps of Engineers at the McCook Experimental Field, Dayton, Ohio. This is generally regarded as the backbone of this class of endeavor in the United States. (2) In Canada, a great deal has been accomplished in a practical way by methods that have not even been tried out in the United States. Under the leadership of the late Doctor Deville, the Dominion Land Surveyors have turned out reconnaissance maps of large areas at very, small cost. (3) Private capital has contributed a great deal toward development of aerial mapping in a practical way in the United States. Prominent in this regard stands the Fairchild Aerial Surveys, Inc. which has spent large sums in research and development work, especially in the construction of aerial cameras. Its camera is, at present, the official camera of the U. S. Army and Navy Air Services, also, of the Canadian and Brazilian governments. Aerial photographic surveying is a flexible process and adapted to a variety of uses. To date, it has proved. of direct practical value for engineering projects such as reservoir and power transmission surveys, railroad location, drainage, harbor front studies; also, for many commercial purposes, tax assessment, city planning, forest surveys, and lawsuits. In a few instances, aerial photographs have been used successfully by geologists as base maps on which to record field observations, thereby dispensing with pacing and compass surveys. There is reason to believe that, eventually, the aerial map will find wide application in the work of geologists. The reason for advancing this opinion is that aerial maps have, in other fields, proved more complete as regards detail than maps made by standard processes of surveying and drafting, and often are more accurate than the latter. At the present time, five distinct uses are being made of aerial photographs: There is the "oblique" photograph taken at an angle with the horizon; it is used extensively for illustrations in newspapers, magazines, and advertisements. Also, for reconnaissance purposes, it has been found of great practical value. For illustrating reports of engineers and geologists, it offers many obvious advantages. In the Canadian Surveys, maps have been compiled from oblique photographs.

Jan 3, 1925

By AIME AIME

SHORTLY after he started his professional career, the subject of this sketch acquired the sobriquet "Moose" Allen. At the time he was engaged in geological exploration it1 the Canadian wilds. The nickname was given .him because of the wide, straight trail that he broke with unusual speed when going through the bush. Like a moose he was strong, energetic, and determined. To a considerable degree, Rolland Craten Allen today displays the same characteristics in larger affairs-business, civic, and professional. It is his habit to study a problem thoroughly, to decide u11on the best course of action, and then to pursue that course with vigor and

Jan 1, 1936

The Institute conducts jointly with the American Society of Civil Engineers, American Society of Mechanical Engineers and American Institute of Electrical Engineers, certain activities as listed below, and is joint owner with them of certain properties. United Engineering Trustees, Inc. When Mr. Carnegie made his gift which made possible a home for the engineering societies, a separate corporation was organized to act as a holding company and to manage the common property. This was long known as the United Engineering Society, but the name has 'now been changed to one which more nearly reflects the real function of the corporation. It holds title to the Engineering Societies Building and to various funds placed in its charge and is managed by a Board of Trustees, of which three are chosen by each of the four societies, American Institute of Mining and Metallurgical Engineers, American Society of Mechanical Engineers, American Institute

Jan 1, 1934

As a service to its readers, MINING ENGINEERING is publishing the mineral industry portion of the 1952 list of "Accredited Undergraduate Engineering Curricula in the United States." This list, revised annually, is issued by the Education Committee of the Engineers Council for Professional Development, and covers all phases of engineering education. The AIME is actively represented on ECPD, which was jointly organized by the Founder Societies and various other groups interested in the professional recognition of engineers.

Jan 4, 1953

By J. C. Martin

Equations for three-phase, three-dimensional, compressible flow (including capillarity) are reduced to two-dimensional relations by a partial integration. This reduction allows three-dimensional flow problems to be treated with mathematics for only two spatial dimensions. The results can be used to formulate flow equations for two-dimensional reservoir simulators in which the effects of capillarity and fluid segregation in the third dimension are represented. Such reservoir simulators would retain many of the aduantages of two-dimensional simulators while simulating three-dimensional effects. The principal restriction of the method is that the thickness of the reservoir should be small, compared to the distance across the reservoir. INTRODUCTION In recent years, computers have been used to calculate the performances of many reservoirs. Most of the detailed calculations, however, are based on finite difference solutions of the flow equations, and present day computers are seldom able to handle a sufficient number of cells to produce entirely satisfactory solutions, even for reservoirs represented by two-dimensional arrays of cells. The situation becomes much worse when one wishes to approximate the reservoir by a three-dimensional array. A great saving in computation or a more detailed solution can be obtained for many reservoirs by using the partial integration of the equations of flow presented in this paper. The integration reduces the three-dimensional equations to two-dimensional relations; and, for studies of two-dimensional flows in vertical cross-sections, the equations are reduced to one-dimensional relations. Most reservoir performance calculations currently are based on one- or two-dimensional flow re1ations.l-3 In some cases flow in the third dimension is approximated by assuming a particular type of vertical saturation distribution, such as gravity segregation.l.2. The relations developed in this paper approach those for segregated flow as the capillary pressures approach zero, and they approach those for uniformly distributed saturations as the capillary pressures are increased. For this analysis, the ratio of the reservoir's thickness to the maximum distance across it must be small. The capillary pressures between the oil and water should also be small compared to the maximum pressure difference in the reservoir. This requirement is met by most reservoirs. It is assumed that the capillary-pressure curves are well defined, whether or not hysteresis effects are included. Also, the reservoir must have sufficient vertical permeability to allow the fluids to segregate. The results presented here provide a firm theoretical foundation to Coats' et aL5 assumption of vertical equilibrium and extend the relations to three-phase flow. Coats' assumption of vertical equilibrium, which he verified by calculations and experiment, is developed here mathematically from basic flow equations. DISCUSSION SATURATION AND PRESSURE DISTRIBUTIONS Appendix A presents a mathematical analysis of fluid flow in reservoirs where the ratio of thickness to maximum distance across the reservoir is small. The results indicate: (1) that the fluids along any line perpendicular to such a reservoir's upper surface are in static capillary equilibrium (vertical equilibrium); (2) that, to a first approximation, the fluid pressures and properties are functions of only areal position in the reservoir and time; and (3) that hydrostatic pressure gradients exist along any line perpendicular to the reservoir's upper surface. The results might be expected after studying several physical considerations. First, no flow is allowed normal to the upper and lower reservoir boundaries, which are relatively close together.

Jan 1, 1969

To the members of the A. I. M. E., who have given much and risked all to fight "Over There" with pick, or gun, or brain, and to the members who have chosen the sometimes more self-denying duty of remaining at home to help produce metals for fighters: Your experience in foreign lands has bred in you that spirit of internationalism which will soon be infused into every corner of our country by virile lads thrilling from a great experience in an old, yet new, land over the seas. To them the East will not seem as far from the West as it was, nor the North from the South. Sectional jealousies will seen despicable to one who has fought for a great ideal shoulder to shoulder with real men of other nations. And they who have willingly sacrificed much on the altar of service will have little patience with an egotist, be he laborer, tradesman, capitalist or engineer. The problems which peace brings to us are more difficult than those of war and their solution requires not only cool heads, tolerance, and wise judgment, but the "getting together" of sections and classes and individuals. The triumph of justice over individualism, represented by the draft law, must be repeated, for there are "slackers" in peace Is well as in war, and the spirit of self-denial expressed in response to Liberty Loans, Red Cross, and Welfare drives and Food Administration appeals must live. We have only just begun to learn how to serve. It is often claimed by our members that the engineer is not given, in the community at large, the recognition which his training should merit; that his reward is not as great nor his service as welcome as it should be. Public service is generally assumed to be a logical activity for a lawyer,

Jan 12, 1918

By AIME AIME

ANNOUNCEMENT on August 6 of the historic event of dropping an atomic bomb on Hiroshima, Japan, was more dramatic even than V-E day, since that had so long been forecast whereas the bomb production had been the best-kept secret of the war, even though at one time more than 100,000 people had been at work in connection with its production, and some two billion dollars had been spent on the project. Mining men had long been aware of an unexplained abnormal interest in uranium production, and suspected that something of the sort was on foot, while metallurgists were aware that various men of their acquaintance were engaged in some top secret research. The first announcement was soon supplemented by other official releases which told more about the research laboratories for theoretical and pilot studies, and the plants in Tennessee and Washington, but none of them made clear what the modus operandi is of these terrific bombs. Inquiry at Colum. bia University, where Dr. Dunning and his associates had succeeded in 1939 in splitting the uranium atom, and where laboratories known only as SAM have been feverishly active since the beginning of the war, was unproductive, since none of those officially connected with the project could give out anything beyond the official releases.

Jan 1, 1945

By Robert Glass Cleland

THE DEATH of William E. Dodge occurred at a time when, all unwittingly, the company in which he had so long been the dominant factor was about to break with its old practices, its old traditions, its old interests, and transfer its major activities three fourths of the way across the continent and engage in an enterprise that differed almost as much from the original Phelps Dodge undertakings as the rough, arid mountains of the new region differed from the green hills and valleys of New England. To understand the effect of this transformation upon the fortunes of Phelps Dodge, one must change the setting of the present narrative from the familiar locale of the Atlantic seaboard to the land of "distance, silence, and solitude," that men called Arizona. In 1880 that Territory was one of the last frontiers of the Old West. To the Spaniards it had been a land of mystery and fable, the limit of the King's settlements, the far edge of the rim of Christendom. Through it Coronado; in a vain effort to find the fabulous Cities of Cibola, had led "the most brilliant company ever assembled in the Indies to go in search of new lands." Below its southern border, Father Kino, the "steel-thewed" Jesuit described by his

Jan 1, 1952

By C. D. Haynes, S. C. Gambrell

The practice of roof bolting in WORLD-WIDE mining activities is very well-known, having been used extensively for over 50 years. The theory of roof bolting, however, is extremely complicated, and only recently have investigators attempted to explain the theory. Various means of stress analysis have been utilized in rock mechanics, most of which reduce rock to an isotropic, homogeneous medium that can be easily analyzed. One of the indirect research methods is the photo-elastic technique, the theory of which is widely known and needs no elaboration. This technique has been used extensively to examine the state of stress around underground openings of various shapes in certain types of strata, and under various loading configurations.'-" In-Situ Mine Roof Trusses The photoelastic technique was employed here to evaluate the state of stress above a mine opening where support is provided by the in-situ mine roof truss. This support configuration, shown in Fig. 1, has gained popularity in recent years, particularly in mines with bad roof conditions." To the authors' knowledge, no scientific determination has been made of the advantages roof trusses may offer over conventional bolting configurations comparable to roof trusses. Ordinary mine roofs usually sag or bulge downward soon after mining. Normally, after some movement the roof begins to stabilize, but the face of this bulging mine rock is usually in tension and will almost always fail unless supported. Because rock fails easily in tension, it is desirable to "preload" the roof, that is, to impress a compressive force on the mine roof to prevent bulging and subsequent tensile failure. Ordinary rock bolting installations, particularly if the bolting is perpendicular to the mine roof plane, do not produce a preloading effect. Although bolting installations squeeze the strata together and produce a beam effect desirable for support, they do not have the advantage of actual uplift. They pull down at the anchorage point with a force equal to the bolt tension which sometimes causes a separation in the plane of the anchorage detrimental to roof strength. In-situ mine roof trusses require the installation of steel tension rods in the roof of the mine much the same as conventional roof bolts, except that the rods are arranged to produce a stress pattern above the upper surface of the opening similar to that of a prestressed beam. The roof rock acts to transmit the compression force. The simplest form of truss consists of two steel rods anchored to the back of holes drilled at an angle of approximately 45 over the mine pillars. These rods are collared near the middle of the room, and the lower ends of the rods are connected by tie rods and turn-buckles. Used in this manner, a small-diameter steel rod can provide essentially the same support as a wide-flange steel beam. By tightening the turnbuckles, an uplift on the roof can be produced. Objective of the Investigation The objective of this investigation was to determine qualitatively the state of stress that exists above a mine roof after the installation of the in-situ mine roof truss vs. that of two angle roof bolts, hereafter referred to as "roof bolts," drilled and placed in the same configuration, that is, 45" above each pillar and connected together in the middle of the room by a bearing member such as a steel beam. Each state of stress was to be identified, insofar as possible, as compression or tension above the mine opening. Model Construction A photoelastic model of a mine opening was coil-structed from -in. thick PLM-4B birefringent plastic and was machined to specification shown in Fig. 2. The dimensions of the opening were chosen to simulate a width-to-depth ratio of 3 to 1. Two % -in. holes were drilled at 45" angles, as shown, to provide for the loading devices. After construction, the model was annealed at 240°F to remove stresses produced during machining.

Jan 1, 1971

By Allen Rogers

TWENTY-FIVE DOLLARS for nothing at all except a sheepskin. That to me is the effect of the New York State law for registration of engineers and the same may be said of any of the state licensing laws. Of course, if one has to practice in more than one state, he must pay a more or less equal amount for every state he works in; and yet there has been little effective protest against these laws. It would seem that the spirit which animated the Boston Tea Party is non-existent amongst engineers. Undoubtedly a good many consider, through their failure to understand the law, that the matter does not affect them. In New York State it is provided that "any person practicing or offering to practice profes-sional engineering or land surveying . . . shall be licensed as hereinafter provided." To quote further from the law: "A person practices professional engi-neering . . . who holds himself out as able to do, or who does, the work that an engineer does . . . " The cunning of the wording of this article can only be appreciated by considering that anyone calling himself an engineer falls within the definition; its liberal inter-pretation (I have not quoted the whole of it) would embrace many who do not consider themselves engi-neers. The state authorities may not construe it to include such individuals; indeed, they may possibly consider it inexpedient to extend it to include engineers of subordinate grade, but the possibility is always there and, even though an engineer be of the grade of assis-tant, he may at any time be called upon to substitute for his principal in responsible charge of the work. It is therefore clear that anyone calling himself engineer and practicing engineering must, for his own protection, apply for registration or run the risk of violating the law. Now, what is the sense of all this? We have done very well without such restrictions on the means of gaining our livelihood. If one only stops to think, there is hardly a minute of his modern existence when he is not dependent for his safety on the engineering by engineers of yesterday or today. How often is one in jeopardy through failure of engineering works, work done under the supervision of those same engineers? If all of us had to wait for our ends by such means, our average life would probably be some thousands of years. Where, then, is the point to the object declared in all these laws that the need for licensing is "to safeguard life, health and property?" Bosh!

Jan 4, 1923

By E. S. Leaver

THE amount of gold that occurs in a ton of milling ore from most of the large-scale copper mines is so small that unusual care and special attention are necessary to recover it. In some cases the gold is not considered important enough to warrant daily assays of the various products. Considering the large tonnage of copper ores that are now concentrated by flotation, as computed in a recent review, the gross gold content is surprisingly large, probably amounting to over 10 million dollars per year in the United States. The indications are that in many of the copper-milling operations with gold content under $1 per ton, only 50 per cent. of the gold is recovered in the flotation concentrates. Lime is generally used as a depressant for pyrite in the flotation circuit. The authors have shown that high lime or a solution high in calcium ions is also a depressant for gold. Their experiments on several well-known ores show that by careful regulation of the alkalinity of the mill solutions, a higher flotation recovery of the gold can be obtained, together with equally good copper recovery in a good grade of copper concentrates. In cyanidation for the recovery of gold, the best accepted practice demands that the mill solutions be tested and regulated by simple chemical reactions at definite periods during treatment or with each change in the treatment. It is similarly important for the recovery of gold that the solution in the flotation circuit be analyzed for calcium ions at regular periods and at each step in the flotation practice. The lime should be added when and where needed and not in excessive amounts at the head of the mill.

Jan 1, 1931

R. F. McELVENNY.- Mr. Oldright has just given me a letter to read to you, which I think it may be of interest. It is headed, "Silver Meeting Dinner". The letter is as follows: "To Members of the A. I. M. & M E.: The annual business meeting and election of officers will take place at the University Club, Wednesday, May 28th, 1930 at 7 p.m., at the Silver Meeting Dinner. The Nominating. Committee for next year's officers have proposed the following names: Chairman, Robert Wallace; Vice-Chairman, G. W. Crane; secretary, C. T. Van Winkle, Other nominations can be made at the meeting. Utah being the leading silver producer of the United States, constructive suggestions regarding the silver situation will be made at this meeting which are new and of general interest to the members. The speak¬ers will be followed by a Round Table discussion of the silver situation and proposed remedies. Speakers will be - W. M. Ferry, President of the Silver Producers' Association, 'Recent developments in the Silver Question'.. Senator Frank J. Cannon, 'The Cannon Plan'. George W. Snyder, 'The Manufacture of Sterling Silver.' Discussion by J. J. Beason, G. W. Crane, J. 0. Elton, J. W. Wade and others. Members of the Conference on Copper Reverberatory Smelting are invited to be present. Chairman J. A. Norden will preside. C. T. Van Winkle, Secretary. Dinner will be $1.50 per plate." The next subject is "Boilers: Proper construction of, so as to secure best utilization of heat from gases, and facility in removing dust and clinker with minimum losses in operation." Who is particularly interested in that subject? The type of boilers is practically a standard practice now. I do not know of anybody that is using the tandem system now. No one is building a plant with a tandem system in it.

Jan 1, 1930

By R. C. Earlougher

Jan 1, 1970

By R. F. Shurtz

The problem of estimating the precision of systematic samples from a mineral deposit is attacked by interpolating the quality, or other attribute measured, by using Fourier approximation. Such approximation using trigonometric functions yields a particularly simple expression for the variance of the mean value of the attribute sampled. The increasing volume of publication in which the science of statistics has been applied to the problem of predicting the quality of an ore deposit from sets of samples taken from it might lead one to believe that engineering judgment can be replaced by statistics. There is, in fact, an implicit application of the principle of indifference or of "no advance knowledge" which has been discredited in modern statistical theory and practice. These pages will show that it is not always advantageous, efficient, or safe to apply this principle. This problem will be dealt with by using series of orthonormal functions to describe the distribution of the quality of ore in space as contrasted with the more commonly used distribution of quality as a frequency function. Mining engineers are rarely well acquainted with the use of such series or of the functions comprising them. These uses are commonplace in the fields of communication and information theory and it is not surprising that applications taken from these fields should be found appropriate for the analysis of the information contained in a set of samples from an ore deposit. It is hoped that presentation of the following basic, but incomplete, results will generate wider interest in this method and a fuller development of it as well as of the necessary computational techniques. FUNDAMENTAL PREMISES Random variables in the strictest sense are not very common in mine sampling. The sets of samples are almost always taken systematically and are, hence, not subject to all the laws governing random events. Therefore, unless there is indeed random experimental error in the determinations of quality, the treatment of systematic samples of n members as though they were random samples of n members often leads to calculation of confidence limits for the mean quality which are larger than they should be with the result that unnecessary additional sampling is done. The reason for this will emerge in the following discussion leading to Eq. 24 and its generalization. In order to inquire into such questions on a rigorous basis and at the same time avoid arithmetic complications that would obscure the concepts involved, a one dimensional distribution of quality will be assumed. The quality, Q, in suitable units is expressed as a function of the distance, x, along some straight traverse of the deposit. Such a function

Jan 1, 1967

By R. W. Raymond

The death of John Frederic Blandy, which occurred September 17, 1903, at Prescott, Arizona, terminated the earthly activity of one of the most active and able of the American mining engineers of the last generation. Mr. Blandy was born, April 24, 1833, at Newark, Delaware. His father was an Englishman, who had been in business in the island of Madeira, and had come thence to settle in the United States. At the age of eighteen, he was attached to the engineering field-corps of the Philadelphia & Reading Railroad; but, after a year of this service, he went to Germany, where he spent three years, entering in 1852 the Mining Academy at Freiberg, Saxony. Graduates of that institution need not be told that, at the period referred to, it held unique prominence in its special field, not only by reason of the great investigators and instructors, such as Cotta, Breithaupt, Weisbach, Plattner and Gaetschmann, who belonged to its faculty and brilliantly blended theory and practice in its work, but also because rival institutions were few. It cannot be fairly said that Freiberg has fallen below its ancient standard of excellence. Its chairs of instruction are still occupied by eminent men, worthy successors of the illustrious teachers who preceded them. But a host of technical academies, especially in this country, munificently equipped and efficiently conducted, have come into existence during the last half-century; and no one institution can ever hereafter claim the pre-eminence which the Freiberg Mining Academy once enjoyed. In those days, American mining engineers returning with satisfactory credentials from that school were sure of immediate employment.

Jan 1, 1904

By R. W. Waterfill

MANY existing ore deposits of valuable metals have been worked out in their upper surface levels and the continued productivity of these mines is dependent on their extension to greater depths in the earth. The maximum depths at present reached are about 6000 to 8000 ft. below the surface, with no evidence of an impoverished ore vein. These mines are widely distributed; some of the best known are in South Africa, Brazil, India and in the western sections of the United States. Among the factors which increase the difficulty of working these mines at increasing depths are hoisting, rock pressure and temperature. The manner and effectiveness with which these problems arc met will, no doubt, determine in a large measure the ultimate depths to which any mine can be profitably worked. The most critical of these three factors at present is the increase in temperature with depth. The high temperature and humidity in many of these mines at present are severely detrimental to the health of the workers and greatly hamper their efficiency. Some have almost reached a condition in which the human system cannot survive. The problems involved in the cooling and ventilation of mines have all been ably analyzed and presented in previous articles. For this reason, only a résumé of conditions affecting the cooling and conditioning of deep and hot mines will be given in this paper before attention is directed to possible methods of improving atmospheric conditions in the working levels. Physiological Effects of Temperature, Humidity and Air Motion Many data on the physiological effects of different atmospheric conditions on the human system have been compiled and published through the combined efforts of the American Society of Heating and Ventilating Engineers, the U. S. Bureau of Mines and U. S. Public Health Service. These data were not primarily developed around the conditions existing in deep mines, but the upper temperature limits of the investigations extend into, and are applicable to, mine atmospheric conditions. While the exact values of the standard comfort conditions, established for persons of such habits as those employed in detecting the different degrees of comfort, might not produce identical effects upon persons inured to

Jan 1, 1929

By Arthur C. Green

A group of 13 cities situated in Los Angeles and Orange counties in Southern California is engaged in constructing an aqueduct to carry water from the Colorado River at a point near Parker, Arizona, to a distribution point near Riverside, California. The aqueduct will have a total length of approximately 241 miles, and is designed to deliver 1605 cu. ft. of water per second, or a little more than one billion gallons per day. The aqueduct crosses a barren, desert waste and the project includes approximately 91 miles of 16-ft. tunnel. The large amount of tunnel driving that has been done in this country in the past few years has resulted in some remarkable developments in equipment and methods. The building of the Colorado River Aqueduct,, with its 91 miles of tunnels, has called on the best engineering knowledge in the country. New and better equipment has been designed for all phases of the work, and this equipment has been coordinated and adapted to the various conditions with a high degree of efficiency. The result has been that records for tunnel driving have been set under adverse natural conditions that exceed the estimates for progress under good conditions. All of the tunnels in the main aqueduct, except the Valverde and Bernasconi at the western end, have a finished diameter, inside the concrete lining, of 16 ft. Fig. 4 shows a section of the tunnel with the concrete lining in place. Fig. 5 illustrates the finished tunnel in three typical sections. The standard tunnel grade is 3.432 ft. per mile in the 16-ft. tunnels, but the Valverde and Bernasconi tunnels have a steeper grade and a finished diameter of 15 ft. 3 in. The rough bore of the large main aqueduct tunnels averages 12.95 solid cubic yards of material per foot of advance in timbered sections and 10.76 solid cubic yards per foot in unsupported sections. Tunnel Driving While the Conway mucker has been used on tunnel work for years, a larger and more powerful Conway was designed to meet the require-

Jan 1, 1937

By Howard N. Hall

The compressibility of reservoir rock is a factor which is generally neglected in reservoir engineering calculations. This is due in part to the fact that there is little published information on rock compressibility values for limestones and sandstones. Omission of rock compressibility is undoubtedly justified in calculations for saturated reservoirs; however, in under-saturated reservoirs,* expansion of the rock accompanying decline in the reservoir pressure may be of such magnitude as to affect materially the prediction of reservoir performance. The effect of rock compressibility will be of most importance in: (1) calculation of oil in place by pressure decline data in undersaturated volumetric reservoirs when the limits of the field are unknown or indefinite, and (2) studies of natural water drive performance. To estimate its importance in such cases, a series of laboratory tests were made to obtain usable values for reservoir rock compressibility. The total, or effective, compressibility of any reservoir rock is a result of two separate factors, namely, expansion of the individual rock grains, as the surrounding fluid pressure de-

Jan 1, 1953

By Howbert Van Dyne

THE Presidio mine of The American Metal Co. of Texas is situated 45 miles south of Marfa, Texas, a town on the Southern Pacific R. R., and lies approximately 20 miles north of the Mexican border. Communication with the railroad is maintained over a state highway. All supplies for mine and mill are hauled in by truck from Marfa and precipitates and concentrates are freighted to the railroad by the same means and shipped to Selby and El Paso, respectively. The mill is at the town of Shafter, 1 mile from the mine and at approximately 350 ft. lower elevation. The ore is conveyed to it by an aerial tramway which requires practically no power on account of the difference in elevation. The mill is a countercurrent decantation cyanide and gravity concentrating plant of 200 tons daily capacity. Coarse and fine crushing are done at the mill. Two near-by shallow wells in the bed of Cibolo Creek furnish an abundance of water. Power is generated for the mill and town by a Diesel engine plant.

Jan 1, 1930

The Engineering Index Service, 29 West 39th St , |New York, N Y. (A division of the American Society of Mechanical Engineers ) This Service is the most complete guide to engineering articles as they are published in current engineering literature of the world All branches of engineering are covered It is prepared on standard library filing cards which are mailed every week. Each card contains complete information as to the source of the article indexed and an annotation, or a description, in which there is sufficient information to enable one to select articles of particular interest. With this Service those interested in any phase of engineering may, with a minimum of time, keep in immediate touch with engineering developments throughout the world There are 225 divisions of the full Service, 31 deal directly with mining engineering, and 15 with metallurgical engineering Divisions may be subscribed to separately or in any desired combinations The cost depends upon the extent to which the Service is used Many divisions are priced at $7 a year. Complete information may be had upon request. A suggested mining engineering group of divisions only, follows Division 1, Abrasive industry, 17, Bituminous materials, 21, Brick industry; 33, Clay products industry, 35, Coal mining industry, 36, Coal preparation industry, 76, Fuel engineering, 78, Geology, 79, Geophysics, 82, Gypsum industry, 99, Insulating materials, 108, Lime and limestone products industry, 109, Liquid fuels, 111, Lubricants and lubrication; 122, Metal mining industry, 127, Mineralogy and rare metals and elements, 128, Mine safety and ventilation, 129, Mining engineering and mineral industry; 130, Mining geology; 136, Natural gas and gasoline industry; 141, Nonmetallic minerals industry, 143, Oil field operation, 146, Ore treatment, 151, Petroleum engineering and industry, 152, Petroleum geology; 153, Petroleum refining industry, 154, Petroleum

Jan 1, 1933