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The 114th (New York) Meeting of the Institute will be held in the third week of February, 1917. The Committee on Papers and Publications has set Dec: 1, 1916; as the closing date for the receipt of manuscripts intended for this meeting. Manuscripts must be received by the Secretary on or before this date. If they are sent through members of the technical committee they must be sent to those committees enough in advance of the time to be forwarded and in the hands of the Secretary by the time specified. While Dec. 1, 1916, is the final closing date, it is a great advantage to get papers in as much before that time as possible as it enables them to be submitted in proof form to their authors. Papers received on or before Nov. 1, 1916, will, as far as possible, be published in the January Bulletin or earlier, thus giving good distribution among the members in advance of tile meeting. The Institute's records show that the discussion of papers is very rnuch better when they are distributed somewhat in advance of the meeting instead of in the Bulletin which goes out immediately preceding the meeting.

Jan 9, 1916

By John Birkinbine

IN the spring of 1878 the Pine Grove Furnace, located in Cumberland County, Pa., was blown in after lying idle for several years. The furnace was constructed in 1770, and for over a century it has been in almost continual operation. The plant consisted in 1877, when the writer was first called there, of a stone stack 32 feet in height, inclosing a shaft and boshes, the latter being 8 feet in diameter. The blast was supplied by two wooden blowing-tubs discharging into a third, having a floating piston sustaining a box weighted to give the desired pressure, the power being furnished by a waterwheel. A small 18-pipe hot-blast stove heated the blast. The furnace was remodelled during the winter of '77-78, and a Weimer blowing-engine with a blowing-tub 5 feet in diameter and 2 feet stroke, and the necessary boilers, were substituted for the wooden tubs and water-wheel. The stack was raised and enlarged, and provided with a bell and hopper having a central drop. Water dam and tymp were added, and general repairs were made. The hot oven, however, was riot increased. The furnace had always been operated with charcoal as fuel, and its reconstruction was made with a view to continue the use of charcoal, but provision was made for ample blowing capacity should other fuels at any time be employed. Although liberal arrangements had been made in cutting wood, the stock of charcoal supplied in 1878 was insufficient for the increased requirements of the remodelled plant, and notwithstanding the purchase of some 80,000 bushels from an adjacent idle furnace, there was riot enough to keep the furnace in constant blast until a new supply could be obtained, particularly as the season was unusually backward. Instead of following the established precedent of many charcoal furnace managers, i. e., blow out every February, it was determined to continue in blast, using coke as fuel. Accordingly, when the charcoal stock was exhausted, on March 22d, 1879, Connellsville coke was substituted, the change of fuel being made at once; that is, the coke charges followed immediately upon the last charcoal charges. After working a few days,-the strike in the Connellsville coke region cut off the supply, and anthracite coal was obtained, a mixture of the two fuels being employed. The strike continuing,

Jan 1, 1880

By McQuiston. F. W., E. C. Tveter

Sulfide mineral flotation has been applied to all naturally occurring sulfides and several synthetics. Of even more importance is the fact that economic separations are now being made between sulfides of essentially all the different metals. The variety of methods and minerals involved in such practice make it difficult to characterize them except in terms of general factors which influence the practices used. Ore grade and mineral composition are the major factors determining the processing method and the extent to which processing must be carried to achieve optimum economic return for a given ore. Since the choice of treatment is also affected by such factors as mine location, shipping charges, smelter schedules, each ore is a separate problem even though mineralization may be similar; The dissemination of minerals in the ore naturally determines the fineness of grind required for liberation. However, since grinding costs are a major part of most milling costs, emphasis has been placed on means of rejecting gangue minerals at the coarsest size possible. This has led to increased flotation of middling products or bulk concentrates for subsequent regrind and retreatment. Reagent development has also played an important part in present plant practice. Relatively few new frothers and collectors have found application during the past 25 years and many have disappeared. In general practice, re- agent combination choice is now fairly consistent with the type of collector being chosen on the basis of the mineral to be floated, the frother on the basis of pulp alkalinity, and the modifiers primarily on the basis of minerals to be rejected. REPRESENTATIVE FLOTATION PLANTS The milling operations described in this chapter have been selected primarily to illustrate these differences in ores and processing methods for the major types of ore minerals. The compositions of these minerals are shown in Table 1. These concentrators were chosen as representatives, both on the basis of geographic location and mineral content of the ore treated. At least one mill is included from each of the major producers, but the primary object was to show the practice employed for the various ore minerals and the different approaches to the middling problems encountered. The individual plants which have contributed data to this study are listed in Table 2, with a summary of their operating data, and are discussed in the order shown.

Jan 1, 1962

By L. E. Young

THE progress of mineral industry education will be limited to the period prior to World War II and will be considered as primarily a division of engineering education. Its relation to progress in the mineral industry and to the activities of the American Institute of Mining and Metallurgical Engineers will be emphasized. The history of mineral industry education has been recorded most completely and authoritatively by Dr. T. T. Read in his recent volume in the Seeley W. Mudd Series of American Institute of Mining and Metallurgical Engineers publications, entitled, The Development of Mineral Industry Education in the United States. Therefore, most of the historical details will be omitted from the discussion and an effort will be made to point out significant developments and to analyze trends. INTRODUCTORY STATEMENT AND SIGNIFICANT POINTS IN PROGRESS Among the significant points in the development of mineral industry education in the United States since 1871, the following deserve particular mention: I. The number of institutions offering undergraduate instruction has increased, particularly during the years 1890 to 1925; the number of students enrolled in undergraduate study has increased greatly, largely on account of the development of courses in petroleum engineering and increasing interest in metallurgy. 2. The selection of students to be admitted to undergraduate courses has been improved through the advisement, counseling, and guidance programs sponsored by the Engineers' Council for Professional Development. 3. Improved instruction methods and the training of the teaching staff have been promoted by the educational institutions themselves, but with the most effective stimulus and guidance of the American Society for Engineering Education and the Engineers' Council for Professional Development. 4. The accrediting of undergraduate curricula through the Engineers' Council for Professional Development, considering both qualitative and quantitative criteria, has done much to improve standards of instruction in engineering education for the mineral industry. 5. Undergraduate curricula and courses are revised currently to meet the needs of the American mineral industry. New curricula are developed currently to permit specialization in technical fields, particularly in the fourth year of undergraduate work. 6. There has been a strengthening of the fundamental courses in mathematics, physics, mechanics, and chemistry, and at the same time these courses are being adapted to the most recent developments in the industry, including metallurgy, geophysics, petroleum engineering, petroleum technology, ceramics and so forth. 7. There has been continuing improvement in plant and laboratory facilities of the educational institutions.

Jan 1, 1947

By Kefton Teague

The minerals discussed in this section have experienced a gradual, although not spectacular, growth in general. Obvious exceptions are the gradual decreasing use of talc and bentonite as filler materials, partly because of availability and relatively lower sales price of competitive materials. Mineral fillers and filter minerals are used principally in those countries that are heavily industrialized. Except for diatomaceous earth of filter grade, most industrialized countries are reasonably self-sufficient in the various filler and filter minerals. Prices of the various mineral commodities during the period 1950-1970 increased approximately as follows: barite, 43%; diatomaceous earth (filler), 49%; diatomaceous earth (filter), 55%; fuller's earth, 55%; talc. 77%; and bentonite, 94%. Actual usage of these mineral commodities as fillers and filters, during this period, showed changes approximately as follows: (1) Decrease-fuller's earth, 6%; talc, 15%; and bentonite, 29%. (2) Increase-barite, 113%; diatomaceous earth (filler), 150%; and diatomaceous earth (filter), -194%. A relationship between the amount of the various fillers and filters used and price increases is apparent. For example, barite increased only 43% in price, but its use as a filler has increased by 113%. On the other hand, talc, which increased 77% in price, decreased in filler use by 15%; and bentonite, which increased 94% in price, has decreased for filler and filter purposes by 29%. The actual decrease in the use of some of these commodities is not entirely caused by an increase in price. Competitive materials frequently have made substantial gains in the various filler and filter markets. For example, much of the bentonite used in the late 1940s and early 1950s for clarification of mineral and vegetable oils has been replaced by competitive materials. BARITE Occurrences and Sources In the United States, barite is produced from about 14 states, listed in approximate order of importance as follows: Missouri, Arkansas, Nevada, Georgia, Alaska, Tennessee, Kentucky, California, New Mexico, North Carolina, Washington, Idaho, South Carolina, Texas, and others. During the 20 years ending in 1970, almost equal amounts of barite were produced from Arkansas and Missouri. Within recent years, Nevada has replaced Georgia as the third leading barite--producing state. West Germany is second to the United States in barite production. Other important barite-producing countries include: Mexico, USSR, Italy, Greece, Canada, and Ireland. Ireland has become an important barite producer only recently. Barite is obtained from vein and cavity fill-

Jan 1, 1976

By John Birkinbine

In the spring of 1878 the Pine Grove Furnace, located in Cumberland County, Pa., was blown in after lying idle for several years. The fnrnace was constructed in 1770, and for over a century it has been in almost continual operation. The plant consisted in 1877, when the writer was first called there, of a stone stack 32 feet in height, inclosing a shaft and boshes, the latter being 8 feet in diameter. The blast was supplid by two wooden blowing-tubs discharging into a third, having a floating piston sustaining a box weighted to give the desired pressure, the power being furnished by a waterwheel. A small 18-pipe hot-blast stove heated the blast. The furnace was remodelled during the winter of'77-78, and a Weimer blowing-engine with a blowing-tub 5 feet in diameter and 2 feet stroke, and the necessary boilers, were substituted for the wooden tubs and water-wheel. The stack was raised and enlarged, and provided with a bell and hopper having a central drop. Water dam and tymp were added, and general repairs were made. The hot oven, however, was not increased. The furnace had always been operated with charcoal as fuel, and its reconstruction was made with a view to continue the use of charcoal, but provision was made for ample blowing capacity should other fuels at any time be employed. Although liberal arrangements had been made in cutting wood, the stock of charcoal supplied in 1878 was insufficient for the increased requirements of the remodelled plant, and notwithstanding the purchase of some 80,000 bushels from an adjacent idle furnace, there war: riot enough to keep the furnace in constant blast until a new supply could be obtained, particularly as the season was unusually backward. Instead of following the established precedent of many charcoal furnace managers, i. e., blow out every February, it was detemined to continue in blast, using coke as fuel. Accordingly, when the charcoal stock was exhansted, on March 22d, 1879, Connellsville coke was substituted, the change of fuel being made at once; that is, the coke charges followed immediately upon the last charcoal charges. After working a few days, the strike in the Connellsville coke region cut of the supply, and anthracite coal was obtained, a mixture of the two fuels being employed. The strike continuing,

Jan 1, 1880

By P. Barnes

(Read at the Philadelphia Meeting, February, 1878.) IT may be of interest, and perhaps of importance, to the members of the Institute that specific mention should be made in detail of the great value of this method of copying or photographing all kinds of tracings.* Several samples are laid upon the table which may serve as illustrations of the results obtained. Some of these show slight imperfections, depending upon the character of the tracing, and upon the length of the exposure to the light, but it may be clearly seen that even a faint copy would be quite available for actual use. The process is believed to be of French origin, and has been used for many years. Special attention seems to have been directed to it recently, and its great value to engineers appears likely to be fully recognized. The manipulations required are of the simplest possible kind, and are entirely within the skill and comprehension of any office boy who can be trusted to copy a letter in an ordinary press. These particulars may be summarized somewhat thus 1. Provide a flat board as. large as the tracing which is to be copied. 2. Lay on this board two or three thicknesses of common blanket, or its equivalent, to give a slightly yielding backing for the paper. 3. Lay on the blanket the prepared paper with the sensitive side uppermost. 4. Lay on this paper the tracing, smoothing it out as perfectly as possible so as to insure a perfect contact with the paper. 5. Lay on the tracing a plate of clear glass, which should be heavy enough to press the tracing close down upon the paper. Ordinary plate-glass of ill thickness is quite sufficient. 6. Expose the whole to a clear sunlight, by pushing it out on a shelf from an ordinary window, or in any other convenient way, for six to ten minutes. If a clear skylight only can be had, the exposure must be continued for thirty or forty-five minutes, and under a cloudy sky, sixty to ninety minutes may be needed. * The introduction of this process into the United States is due principally to Mr. A. L. Holley, who first drew the attention of American engineers to its simplicity and convenience. Mention was also made of the process at the meeting of the Institute in New York, in February, 1877, by Mr. Ogden Haight.

Jan 1, 1878

By W. A. Ver Wiebe

The year 1939 in Kansas, with a production of 57,944,300 bbl. from 19,669 wells, shows a slight recession from the peak of oil production reached the previous year, when slightly over 59,000,000 bbl. of oil was marketed. The previous peak had been reached in 1917 with 45,451,000 bbl. marketed. Another still earlier peak had been reached in 1904, when slightly less than 5,000,000 bbl. was produced and sold. The production of gas probably reached a new peak during 1939 with a total of over 69 billion cubic feet. Between the peak of the year 1908, when over 80 billion cu. ft. was produced, and that of 1939 the production dropped to 16 billion cu. ft., in the year 1921. During the year 1458 wells were drilled. This figure is somewhat lower than that given in several trade journals, because it does not include wells that were deepened or recompleted in a different geological horizon. Nearly 75 per cent (1029) of the total number of wells were completed as commercial oil wells (824 in western and 205 in eastern Kansas). The commercial gas wells completed number 71, of which 24 are in eastern Kansas and 47 in western Kansas. The remaining completions include 154 dry holes in eastern and 204 dry holes in western Kansas. Based on daily potential capacity the new discoveries of the year accounted for a cumulative initial production of 264,000 bbl. in eastern and 1,158,827 bbl. in western Kansas. It is interesting in this connection to note that the number of wells completed in the state rose gradually to a first peak in 1904, when 2782 were drilled. The number dropped off rapidly to 368 three years later, but rose to the second and highest peak in 1918, when 4671 wells were completed. In the period between 1904 and 1912 more gas wells than oil wells were completed. Between the high peak of 1918 and the somewhat lower peak of 1937, the low point was reached during 1931 with the completion of only 470 wells. In the matter of new pools discovered, Kansas again ranks high. The exact number depends somewhat upon the interpretation of a "new" area—whether it should be called a new pool or a long extension of an older pool. In some places this determination cannot be made until more wells are drilled within the area. Therefore, the figures given

Jan 1, 1940

By W. A. Ver Wiebe

The year 1939 in Kansas, with a production of 57,944,300 bbl. from 19,669 wells, shows a slight recession from the peak of oil production reached the previous year, when slightly over 59,000,000 bbl. of oil was marketed. The previous peak had been reached in 1917 with 45,451,000 bbl. marketed. Another still earlier peak had been reached in 1904, when slightly less than 5,000,000 bbl. was produced and sold. The production of gas probably reached a new peak during 1939 with a total of over 69 billion cubic feet. Between the peak of the year 1908, when over 80 billion cu. ft. was produced, and that of 1939 the production dropped to 16 billion cu. ft., in the year 1921. During the year 1458 wells were drilled. This figure is somewhat lower than that given in several trade journals, because it does not include wells that were deepened or recompleted in a different geological horizon. Nearly 75 per cent (1029) of the total number of wells were completed as commercial oil wells (824 in western and 205 in eastern Kansas). The commercial gas wells completed number 71, of which 24 are in eastern Kansas and 47 in western Kansas. The remaining completions include 154 dry holes in eastern and 204 dry holes in western Kansas. Based on daily potential capacity the new discoveries of the year accounted for a cumulative initial production of 264,000 bbl. in eastern and 1,158,827 bbl. in western Kansas. It is interesting in this connection to note that the number of wells completed in the state rose gradually to a first peak in 1904, when 2782 were drilled. The number dropped off rapidly to 368 three years later, but rose to the second and highest peak in 1918, when 4671 wells were completed. In the period between 1904 and 1912 more gas wells than oil wells were completed. Between the high peak of 1918 and the somewhat lower peak of 1937, the low point was reached during 1931 with the completion of only 470 wells. In the matter of new pools discovered, Kansas again ranks high. The exact number depends somewhat upon the interpretation of a "new" area—whether it should be called a new pool or a long extension of an older pool. In some places this determination cannot be made until more wells are drilled within the area. Therefore, the figures given

Jan 1, 1940

By C. T. Bischoff

DURING the past few years geochemical testing for traces of heavy metals in water, soil, rock, and vegetation has aroused increasing interest. Various techniques for field and laboratory determinations have been described in the literature, as have some of the results of application. However, little information has been published regarding application to glacial terrain. Over 90 pct of the Canadian Shield is overburdened, resulting in high costs for mineral exploration once the outcropping ore deposits have been found. This has been largely responsible for the widespread application of mining geophysics in Canada, permitting concentration of effort on area or zones considered most favorable. However, geophysical interpretation has its limitations, since at least 90 pct of the structures indicated thereby contain no valuable minerals. A more direct approach is therefore highly desirable. If underlying base metal mineralization can be detected by sampling soil or vegetation at moderate cost this should prove of great help in locating new discoveries or extending known ones. A large proportion of Canadian ore deposits contain appreciable copper or zinc, even where these are not the principal economic metals. Consequently the field of application is a broad one.

Jan 1, 1954

By AIME AIME

THE Employment Bureau of the F. A: E. S., conducted under- the direct supervision of the secretaries of the four Founder Societies, has wanted to extend its activities and usefulness but it is operating right up to the limit of its budget; consequently, anything which requires the expenditure of more funds cannot be -undertaken, for the present. A great deal of time has been spent in recording, classifying, and interviewing the men listed, but owing to the business depression, only a comparatively small number of men have been placed' luring the last few months. There are men in New York from all over the country. What the Bureau needs is more positions available. With this in view, a number of high-grade engineers, themselves in need of employment, volunteered their services for a publicity campaign in the City of New York. A definite mode of procedure was evolved, and the success of the movement has been considerable, so much so that it has been thought well to call it to the attention, of members elsewhere, so that similar committees ' and campaigns might be organized in other cities. Following is a chronological arrangement of the methods used.

Jan 1, 1921

By R. E. Bish

IN an effort to distinguish experimentally between the radically different limits of two-liquid im-miscibility reported for the Cu-Pb system by Borne-inann and Wagenmann and by Briesemeister (see Fig. I), it was found that the high temperature homogeneous liquid containing between 41 and 93 pct Pb could not be frozen without separation into two liquids with the fastest cooling technique that could be devised. Thus, the two-phase state could not be distinguished with certainty from the one-phase state by the examination of quenched samples. To overcome this obstacle the following method for detecting the presence of an interface between two immiscible conducting liquids at temperature was developed. Measurements made by the new method substantiate the Briesemeister diagram in its general form. The method consists essentially in the measure-

Jan 1, 1953

THE New York Petroleum Club has elected the following officers for the current year: Chairman, William B. Heroy; vice-chairmen, Edwin B. Hopkins, Warren. A. Sinsheimer; secretary, A. C. Hunter. This is the local section of the Petroleum Division. It holds monthly lunch-eons, usually in the rooms of the Railway Club.

Jan 3, 1927

By William L. Payne, Edward E. Ives

A unique feature of Potash Co. of America's A new potash property near Saskatoon, Sask., is the use of semi-dome-shaped buildings for product storage. Four domed structures, timber-framed and corrugated-sheet covered, are being built; each designed to handle 20,000 cu yd. The relatively small capacity units, PCA believes, give flexibility not only in storing different grades and sizes of product, but also in permitting greater ease in shipping products as market demands change. The domed buildings are 150-ft diam, comprised of a 16-ft-high concrete wall base, topped with a metal sheet-covered octagonal timber frame. The dome of each unit is designed to fit very closely the angle of repose of the contained material, which results in the maximum usable volume. The entire roof is flood coated with a bitumin to provide a complete weather seal.

Jan 9, 1959

By Takeyasu Ito, Mayumi Someno, Kazuhiro Goto

SINCE the pioneering work by Kiukkola and Wagner,1 many experiments have been reported on solid electrochemistry at elevated temperatures. However, the studies have been confined to experiments under isothermal conditions. One may conceive many situations under nonisothermal conditions. With two different temperatures T1, and T2 at the two electrodes, the electromotive force, E of a Galvanic cell will be expressed by the following equation under a steady state heat transfer in solid electrolytes of zirconia-lime and thoria-lime. E = ^ $ l&-dGO2+a(T2-Ti) [1] where tO2- is the transference number of oxygen ions in the electrolyte, Go, is the chemical potential of oxygen, and a is the coefficient of the thermoelec-tromotive force due to the temperature difference. The objective of the present study was to evaluate the coefficient of the thermoelectromotive force for zirconia-lime and thoria-lime under isobaric condition. The physical meaning of this coefficient is out of the scope of the present communication. The experimental cell assembly is schematically shown in Fig. 1. The zirconia-lime electrolyte tube and thoria-lime electrolyte tube were 8.0 mm OD and 5.0 ID, from commercial sources with chemical analyses of 94.8 wt pct ZrO2, 3.85 pct CaO, 0.83 pct SiO2, 0.25 pct TiO2, and 0.05 pct Fe2O3; and 95.0 pct ThO2, 4.0 pct CaO and rare earth metal oxides, respectively. The specific gravity was 5.5 g per cu cm for zirconia-lime and 9.8 g per cu cm for thoria-lime. Original powder size before shaping and sintering the tube was several microns for both electrolytes. The distance separating the two electrodes was 4.0 or 5.0 cm. Platinum wire of 0.5 mm diam was used for the electrodes. The temperature gradient was controlled by heating one electrode with a small heating coil of nichrome wire. The temperatures at the two electrodes were measured with two calibrated Pt-13 pct Rh:Pt thermocouples, directly contacting the two platinum electrodes. The atmosphere was either air or pure oxygen. The partial pressure of oxygen in air was considered equal at the vicinities of the two electrodes, with negligibly small thermal segregation in the gas phase. The difference of the chemical potential of oxygen was controlled only by the temperature difference at the two electrodes and not by the oxygen pressure difference. The temperature ranges were 600" to 1200°C for zirconia-lime and 850" to 1200°C for thoria-lime electrolytes. Fig. 2 shows the relation of the measured electromotive force and the difference of the oxygen chemical potential at the two electrodes for zirconia-lime and thoria-lime electrolytes. The electromotive forces in the figure were measured by a *0.05 mv potentiometer. The chemical potential difference was calculated by the following equations.'

Jan 1, 1970

By Louis P. Gignac

INTRODUCTION The selection of trackless equipment for underground mining can be a complex engineering problem due to the wide range of equipment sizes and operating modes. Computer simulation is particularly useful in estimating the performance of different systems for specific rock- handling problems. A hybrid simulator, incorporating some of the features of deterministic and stochastic simulation, was developed in order to handle not only queuing delays at loading and dumping points, but a1 so traffic interferences. Any number of vehicles can operate in any one of four basic modes (LHD, LAF, FEL, HFC) in parallel or in series. If the units use common roadways, loading and dumping points, certain operating delays will occur and be registered by the simulator and thus give a better evaluation of the marginal productivity of each additional unit. Based on a typical layout of drawpoints and ore passes for the sub-level stoping method, productivity and operating costs of different rock-handling systems will be examined. 1 . COMPUTER SIMULATION Numerous applications of computer simulations are reported in the 1iterature for various mining problems. Depending on the complexity of the system to be studied, simulation models were conceived with different degrees of sophistication. Three different types of simulators are generally recognized: stochastic, deterministic, and hybrid. Stochastic or Monte Carl o simulation randomly generates items, transactions, or events from some population defined by a frequency distribution and produces some expected future situations. Because this type of simulation is governed by the input of probability distributions, it requires a detailed knowledge of the system to be simulated; it implies expensive and time-consuming studies and reports to gene- rate this input information. A major short- coming of stochastic techniques is in new equipment evaluation, where the lack of data is unavoidable, and in new system design where the conditions are outside the range of the known historical behavior of the equipment. However, probabilistic simulation is almost essential for the study of cyclic queues and traffic problems. Deterministic simulation studies a system by generating performances on the basis of the mechanical capabilities of the vehicles and the physical limitations of the mining scheme. It is based on the engineering principle that the engine converts its energy into a rimpull at the wheels, which is in turn opposed by the rolling resistance and the grade of the ground; the machine is accelerated or decelerated until the tractive and resistive forces are in equilibrium, at which point it moves at constant speed. The information required by this technique, such as rimpull charts and equipment weight, is readily available from equipment suppliers. However, equipment performance at the mining site is also dictated by human and environmental conditions and changes with time and usage. For this reason, deterministic simulation generally overestimates the system capabilities; these must then be adjusted by efficiency factors based on observation and experience. Recently, hybrid simulation models, using both stochastic and deterministic techniques, have been built with some of the events generated stochasticly and others being deterministic. This compromising approach originated at the Pennsylvania State University. O'Nei1 (1966) designed a simulator for truck-and- shovel operations that allows for transportation from multiple faces to mu1tiple destinations. Each truck performs according to its mechanical capabilities while its loading and dumping time and its load fluctuate according to specific probability distributions. A major advance in the simulation of mining systems is due to Sanford's model (1969) of underground coal mining operations. The originality of the model is in the use of an Executive System Control which sets up the initial system, de- fines the operation conditions , and instructs continuously four sub-assemblies representing shuttle cars, trains, continuous miners , and conveyors, which in turn generate a feed-back of their movement to the Executive Control System for further instructions. The model has enough flexibility to simulate simultaneous and sequential jobs that characterize any dynamic system. Sanford's early work evolved slowly to what is known today as the Under- ground Materials Handling Simulator for coal mining (Manula, 1974).

Jan 1, 1981

By Walter English

THE four papers making up this symposum have been prepared espe-cially for those who have no knowledge of seismograph prospecting. To many people mathematics is a formidable subject, and many are discouraged from studying seismograph prospecting under the mistaken assumption that the mathematical requirements are severe. In the papers presented here there is not a single mathematical equation. We believe that considerable competence in dealing with some of the most important problems of this work can be attained without any mathe-matical training whatever. At the present time, there is a real need for interpretation of results by persons thoroughly competent to bring geologic experience and imagination to bear on data that are subject to multiple interpretation from a strictly physical viewpoint. Likewise, those charged with the responsibility of planning seismo-graph exploration campaigns would do well to become familiar with as much as possible of the technical aspects of the work. They would then be in better position to judge of its success in individual cases. It has often been said that the seismograph is a new structure-finding tool for the geologists to use. Using a tool and using its product are two different things. One does not use an automatic screw-threading machine when he buys a box of screws at the hardware store. Neither does the geologist

Jan 1, 1939

Carlisle: This is April 19, 1961. My good friend Dave Irwin is sitting on the other side of the tape recorder. We are at Rose Dhu Island, Savannah, Ga. Now, let's begin with your first job, where and what was that? Irwin: I started out to Arizona, looking for a job and wound up in Morenci. The next morning I applied at the mine office and was put on as a sampler. I worked as a sampler and as an assistant to Frank Pelton, the geologist, for a year, after which I went back to New Haven to take my last year of postgraduate work. After getting my degree, I went back to the Southwest with W. Rowland Cox and Staff, supposedly as a geologist. Q: But that was not when he was with Spurr? Irwin: That was after he had left Spurr. Henry Smith was with the Spurr end of the outfit and I happened to drop into the W. Rowland Cox end. My first job with him was to do some work on a prospect above Metcalf, Ariz., and from there I would go out on short reconnaissance trips in Arizona, New Mexico and old Mexico.

Jan 6, 1964

By Rudolf Bernhard

STATIC soil investigations with more or less heavy loads and extensive borings do not always have efficient results; also, they are very expensive. The new geophysical method of dynamic tests described herein is simple and cheap and avoids several disadvantages of the routine investigation, thus forming a useful supplement to the older methods and even at times replacing various static tests. The fundamental principle of dynamic soil tests consists in the appli-cation of artificial vibration. The technique employed is essentially geophysical in nature and in some respects is akin to seismic studies. Artificial vibration may be excited by centrifugal forces resulting from eccentrically supported rotating masses. The reactions of soil and structures caused by these vibrations may be measured. Their dynamic constants, such as amplitudes, phase speeds, damping, reflection, and interference effects, can be investigated. This geophysical method has been used for several years with increasing success. The results of these tests, summarized at the end of the paper, indicate that this method opens a new field for the practical engineer in investigating soils (capacity and formation), foundations, dams and structures, and especially buildings that must withstand earthquakes.

Jan 1, 1938

By Marvin P. Barnes

Definition The term mineral inventory is a relatively new designation, born of the computer age and grown to common usage with the development of computer techniques for extending drill-hole sample values to regularly gridded data blocks representing in situ mineral values. The term has been generally accepted by geologists and engineers because it has a precise meaning which avoids many of the ambiguities of ore reserve. A mineral inventory is an estimated inventory of mineral in place and is usually achieved by dividing the deposit into regularly spaced gridded blocks to which are assigned estimated values using various extension techniques. A mineral Inventory makes no presumptions about the minability of the blocks or their cutoff grade. A mineral inventory estimate may be good or poor according to how much is known about the deposit, how extensively it has been sampled, and what techniques have been employed to assign estimated grade to the blocks Such an inventory, however, does not change with time, economic conditions, or mining technology, but only with new and better data and methods. Thus, the mineral Inventory is an excellent designation for describing mineral value distributron within a deposit's geological setting

Jan 1, 1979