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By R. S. Lewis

IN a recent study1 of the evolution of engineering education 1870 was taken as the initial point, as it is said to mark the transition from the poineer era in American engineering education to an era of rapid growth and consistent development. Prior to the founding of Rensselaer Polytechnic Institute in 1824, West Point Military Academy was the principal source of formal engineering training. In 1849 Rensselaer revised its program on the model of the leading French technical schools. Lawrence Scientific School was estab-lished at Harvard and Sheffield Scientific School at Yale in 1847. The University of Michigan pioneered in en-gineering instruction in the West, offering its first course in 1853 and awarding its first degree in 1860. Other important steps in -the progress of engineering education were the founding of Columbia School of' Mines in 1864, the opening of Massachusetts Institute of Technology in 1865, and the founding of Cornell Uni-versity and the Thayer School of Civil Engineering at Dartmouth in 1867. From its organization in 1852 until 1871 the Ameri-can Society of Civil Engineers was virtually the only national society of engineers. In 1871 the American Institute of-Mining and Metallurgical Engineers was founded, to be followed later by the Mechanical En-gineers in 1880 and the Electrical Engineers in 1884. This expansion and diversification of the engineering profession was paralleled in the colleges, and by 1885 the plan of different curricula in the major branches of engineering was soundly established.

Jan 7, 1927

By Peter I. Brooker

Elementary estimation methods in which blocks are assigned values according to a geometrical area of influence concept are investigated for a tabular deposit. This quantitative assessment of the estimation technique is made using Matheron's geostatistics which allows the variance of the error between actual block values and estimated values to be found once the semi-variogram is known. For the deposit in question it is shown that the elementary technique makes poor use of the available information. There is a 20% relative error associated with it, whereas by using the optimal technique of kriging this can be reduced to 9%. An infill drilling program, which might have been suggested on area of influence results, would reduce the estimation variance only marginally over that of the current campaign; the relative error being lowered to 6%. Thus the geostatistical analysis shows this would be an unnecessary expense. The accuracy of an earlier drilling stage is also studied and it is shown that with the information available at the earlier stage block values could have been known with a relative error of 13%. Drilling could have stopped then if this were reckoned a tolerable error level. These results are all obtained for blocks whose size is dictated by the mining engineer and is set at the current grid size. In the area of influence approach smaller blocks are considered as the grid becomes finer and a study of the accuracy of area of influence estimates and kriged estimates for differing block sizes is presented. Between drilling stages more information from which the semi- variogram is calculated becomes available. The sensitivity of the estimation to changes in the semi-variogram parameters between earlier and current drilling programs is investigated.

Jan 1, 1977

Jan 1, 1929

Jan 1, 1943

Jan 1, 1929

Jan 1, 1943

Jan 1, 1931

By W. C. Lacy

A WIDE variety of metalliferous deposits in Peru shows a close and consistent relationship to intrusive and extrusive igneous rocks. This relation- ship furnishes a clue to the composition of ore-bearing fluids and to the timing in separation of these fluids from differentiation magma. Conclusions presented here are based on ten years' study of a large number of metalliferous deposits in Peru. The most important of these areas are shown in Fig. 1.

Jan 5, 1957

By S. G. Lasky

Abraham Lincoln is reputed to have said that if you want to chart a course to some destination, you have to know where you are starting from. In this instance we have to define our starting point in a double manner: 1) What was the theoretical basis of the Paley predictions? 2) What actually did the Commission predict, so that we can see how the predictions have worked out up to now as a basis for considering how they may have to be changed.

Jan 3, 1960

By S. Suphi Yavasca, A. M. Gaudin

This paper is intended as a contribution to our knowledge of the mechanism of comminution and of the work of crushing. In a previous paper1 it was shown that with quartz comminution proceeds as follows: 1. The size distribution of broken fragments made by a single fracture is such that the new surface on each grade is the same. 2. Multiple fracturing results in a size distribution such that in the he sizes the surface per grade is the same in every grade; in coarse sizes the surface per grade decreases gradually with increasing size. In that paper it was mentioned that determinations on minerals other than quartz were in course of completion in order to establish the generality of these observations. In this paper, condensed data1 are presented for galena, pyrite and glass. Galena and pyrite are crystalline materials and glass is noncrystalline. Galena has excellent cubic cleavage. Pyrite, although cubical, does not have marked cleavage. Quartz, on which the original determinations were made, does not cleave and although crystalline (hexagonal) breaks conchoidally. Glass breaks much like quartz. It is apparent, therefore, that the minerals selected represent some range in character of the solid without covering all possible types. Glass Fifteen glass marbles were crushed individually in the pendulum crusher described in the preceding paper,' then subjected to careful screening for 30 min. Six sized fractions were selected and cleaned in a hot 0.12 N solution of hydrochloric acid, washed with distilled water and dried on a hot plate. This was followed by an examination with a binocular microscope, to remove foreign matters not eliminated in cleaning as well as to eliminate "compacts" of fine particles. These compacts are groups of he irag-ments that seem to be mechanically stuck together as a result of localized compacting during the comminution operation. The presence and the abundance of these compacts may be related to the amount and direction of the forces applied in different crushing devices. Since, properly, such compacts should be entirely eliminated in the sizing analyses, it is necessary to remove them to the last before making surface determinations on sized fractions. For example, with a — 28 + 35-mesh glass the surface areas of two samples, one cleaned with acid and under the binocular, the other only washed, were 102 and 172. cm' per gram, respectively. Examination of the samples under an Ultropak microscope showed that washing alone failed to remove the compacts and also that it fails to remove certain fine dusts attached to the particles. Cleaning with acid loosens the fine dusts and

Jan 1, 1947

By S. Suphi Yavasca, A. M. Gaudin

This paper is intended as a contribution to our knowledge of the mechanism of comminution and of the work of crushing. In a previous paper1 it was shown that with quartz comminution proceeds as follows: 1. The size distribution of broken fragments made by a single fracture is such that the new surface on each grade is the same. 2. Multiple fracturing results in a size distribution such that in the he sizes the surface per grade is the same in every grade; in coarse sizes the surface per grade decreases gradually with increasing size. In that paper it was mentioned that determinations on minerals other than quartz were in course of completion in order to establish the generality of these observations. In this paper, condensed data1 are presented for galena, pyrite and glass. Galena and pyrite are crystalline materials and glass is noncrystalline. Galena has excellent cubic cleavage. Pyrite, although cubical, does not have marked cleavage. Quartz, on which the original determinations were made, does not cleave and although crystalline (hexagonal) breaks conchoidally. Glass breaks much like quartz. It is apparent, therefore, that the minerals selected represent some range in character of the solid without covering all possible types. Glass Fifteen glass marbles were crushed individually in the pendulum crusher described in the preceding paper,' then subjected to careful screening for 30 min. Six sized fractions were selected and cleaned in a hot 0.12 N solution of hydrochloric acid, washed with distilled water and dried on a hot plate. This was followed by an examination with a binocular microscope, to remove foreign matters not eliminated in cleaning as well as to eliminate "compacts" of fine particles. These compacts are groups of he irag-ments that seem to be mechanically stuck together as a result of localized compacting during the comminution operation. The presence and the abundance of these compacts may be related to the amount and direction of the forces applied in different crushing devices. Since, properly, such compacts should be entirely eliminated in the sizing analyses, it is necessary to remove them to the last before making surface determinations on sized fractions. For example, with a — 28 + 35-mesh glass the surface areas of two samples, one cleaned with acid and under the binocular, the other only washed, were 102 and 172. cm' per gram, respectively. Examination of the samples under an Ultropak microscope showed that washing alone failed to remove the compacts and also that it fails to remove certain fine dusts attached to the particles. Cleaning with acid loosens the fine dusts and

Jan 1, 1947

In the examination of an undeveloped prospect a decision must be arrived at from an inspection of the outcrops and the exposures in a few shallow pits. Prospects that are offered for sale rarely expose any important quantity of good ore, work having usually been stopped when the immediate exploration no longer yielded favorable results. It should be borne in mind, furthermore, that a great majority of prospects have been examined many times, and if of conspicuous promise, would have been acquired-for development. In most cases the problem for the engineer, therefore, is to discover the traces of a valuable mineralization that has disappeared through solution, or the conditions that indicate the possibility, or probability, of underlying secondary enrichments. The available data being meager, every feature should be the subject of careful study-the condition of the outcrop, the structural relationships, the associations of minerals, the alterations of wall rocks, the chances for underlying enrichments, and so forth, as well as the actual assay value of the material exposed. It is frequently advisable to spend the time and money necessary to have trenches dug at various significant points along a promising outcrop; such exposures, even if the depth attained is slight, often disclose conditions that are not apparent at the actual surface, as for example, the existence of soft minerals and the distribution of the various minerals through the mass of the deposit. Trenches also permit samples to be taken from points that were not accessible during former examinations. Strong, persistent outcrops of uniform width may be taken to indicate the probable size and character of the underlying vein,

Jan 1, 1932

Two sessions during the recent AMC Mining Convention in Los Angeles, September 23-26, served to update industry personnel on the status of health and safety regulations in the US. As reflected by the American Mining Congress resolution on mine safety and health, "Based on experience with the federal Coal Mine Health and Safety Act of 1969 and the federal Mine Safety and Health Act of 1977, (AMC) does not believe that laws designed to force compliance with regulations through the imposition of criminal or civil penalties will result in safer mines. (AMC) feels that the government's participation will be much more productive if greater emphasis is placed on research, training, and inspections aimed primarily at assisting operators and employees in recognizing and eliminating hazardous conditions and practices.

Jan 11, 1979

By Glenn C. Waterman

The use of stream sediment and soil sampling as an aid in exploration has markedly increased in recent years as more and more attention has been directed to areas that are generally geologically favorable for mineralization but show little outcrop. Numerous ore deposits and many hundreds of mineral deposits that have no surface exposure have been found associated with anomalous geochemical patterns. Sophisticated techniques have been developed to "wring out" of geochemical data subtle information that is pertinent in defining areas of exploration interest. Variations in metal patterns in soils and sediments as they are affected by pH, Eh, weather, topography, etc., are pretty well known. Field studies have determined the variations and controls of metal ion distribution in the several soil horizons and the contributions to metal concentrations made by different types of vegetation. Less well known is how to interpret geochemical data since thickness of soils over bedrock varies in an unknown fashion and, particularly, where glacial debris of unknown thickness is piled on top of soils or scoured bedrock.

Jan 7, 1975

By James C. Fisher

Traditional uranium exploration techniques were utilized and comparatively evaluated in the Front Range, Colorado uranium province. Intense surficial leaching and thick colluvial cover render traditional airborne and ground radioactivity reconnaissance prospecting useless. Radon gas emanometry and sulfur gas emanometry were slightly more effective but the long and short term variations In soil gas emanation rates make it extremely difficult to gain useful information from these systems. The technique judged most useful was Track Etch radon prospecting. The excellent definition of the technique, as well as its repeatability, indicate that it is an ideal prospecting tool for narrow vein-type deposits similar to those of the Front Range, Colorado.

Jan 1, 1976

By H. C. Fiedler

SILICON-IRON strip with a cube-on-edge secondary recrystallization texture is made commercially as thin as 10 mils. With inclusions present to inhibit normal grain growth, a few grains, and these have the (110)[001] orientation, grow very large at the expense of the matrix grains. In the absence of inclusions, only normal grain growth occurs and the texture is not as strong as when it is developed by secondary recrystallization.1 Strip for use at frequencies of 400 cps and higher is made in thicknesses of 1, 2, and 4 mils by a process developed by Littmann.2 Attempts to develop a strong texture in these thin gages by the same methods as were used for the 10 mil and thicker strip were unsuccessful,2 and Littmann's solution to this problem was to cold roll the grain

Jan 1, 1963

By R. J. Robbins, D. L. Anderson

A tunnel boring machine has potential use in al- most any type of mining where the access shaft (or adit) is large enough or can be made large enough for its initial entry and where the orebody is of sufficient size to warrant its use. Some time will inevitably be lost in negotiating curves or making lateral moves and moving from level to level. Nevertheless, if the orebody is sufficiently large, advance scheduling can minimize the lost time encountered in such moves. Ideally, a mine will be planned for the use of these machines, thus eliminating access and transport problems. From the viewpoint of time involved, the rate of advance by boring as compared to conventional means is worthy of review. For instance, the Blanco Tunnel, one section of the Bureau of Reclamation's San Juan-Chama Project in southern Colorado, was bored in competent sedimentary rock with the following performance:

Jan 7, 1967

By R. C. Mahon

THE Homer iron-ore mine is at Iron River, Mich. Because it covers a large area, 400 acres, and because there was a considerable depth of water in the glacial drift above most of the ore bodies, this mine has presented a number of unusual and often difficult operational problems. The purpose of this paper is to discuss a few of the most important problems encountered. SURFACE WATER Mining on this property was started on one 40-acre tract. The ledge in this area was the highest on the property and, although it was a real problem, water could be handled by underground pumping. During the first period of mining, drifts were driven just under the ledge and holes were drilled through to the surface material. In later years these drifts have been extended wherever possible. Although these drifts assisted in the drainage problem, it was evident they would not be sufficient alone. Before mining on a large scale could be started on this property, the water problem had to be solved. A number of test holes were put down to the ledge, and showed that there was an average 150 ft. of water-saturated glacial drift above the ledge over the rest of the mine. The upper 70 ft. was gravel and sand and the lower 80 ft. clay and hard pan, with some narrow seams of sand and gravel. It was evident that the water above the clay seam could not be drained off through openings in the ledge and for that reason it was decided to install surface drainage wells. This method of drainage was entirely new at that time and was pioneered at the Homer mine. The sinking of the first well was started in June 1929. Immediately following the first well a number of wells were sunk, but only to the top of the clay seam. This was done with the idea that a greater capacity could be obtained in a shorter time from gravel seams where the water flowed more freely and that the cost of pumping the water above the clay seam would be considerably less than if the wells had all been sunk to the ledge at once. Before the drainage of surface water was started, 1200 gal. per min. against a head of 800 ft. was being pumped from the mine. By March of 1932, with five surface wells in operation, the mine pumping had been reduced to 150 gal. per min. At this time we were pumping 5000 gal. per min., under an average head of 110 ft. from the surface wells. The total pumping costs were 30 per cent less than in 1929 because the greater capacity was being pumped at a much lower head. From 1932 to 1936 the mine was idle and all surface pumping was stopped. Since 1936, 10 new wells have been added with a total pumping capacity of 8000 gal. per min. at the present time. The water level has been lowered 70 ft. since surface pumping was started in 1929, and it is now approximately at the top of the clay. To remove the water below the clay seam, 11 of the 15 wells were sunk to the ledge.

Jan 1, 1945

By H. P. Schwede, H. G. Doll

This paper describes a method to provide identification of particular depths in a borehole through the use of radioactive markers. The correlation of a marker, placed in the wall of a borehole, with known points of the electrical log and with the casing collars in the cased hole permits accurate positioning of tools with respect to a formation, regardless of absolute depth. Such a process is particularly useful in gun perforation of a casing in a well. Technique and equipment are discussed and illustrated. Examples are given of practical application in the field. Introduction During the past decade the search for petroleum has increased the importance of testing zones at depths in wells which have become progressively deeper. The development of new techniques, such as electrical logging, has permitted the identification of producing formations which consist of comparatively thin strata. When thin beds are to be produced at great depths, the problem of positioning tools accurately to place the well in production becomes acute.l Continuous consideration is being given in the petroleum industry towards the improvement of depth measurements in a borehole. The accuracy in absolute depth measurements, whether made in an open or cased hole, whether determined by a cable or a drill pipe, depends upon a number of factors, such as tension, temperature, and calibration. For example, the effects of tension from the weight of 10,000 ft of drill pipe and the thermal expansion of this length . of pipe, where its average temperature has increased SO"', will Produce an elongation as much as 8 ft.2 The effects Of such factors can be minimized through the use of care in depth measurements, the application of corrections based on experience, and continuous calibration or checking. The fact that different methods and different tools are used to determine the depths of formations in wells will sometimes give rise to a difference between measurements. It is evident that an important requirement in a well is the ability to locate at will any subsurface point. While absolute depth measurements have ion in recent years, it is reassuring to have other means to verify, for example, that a casing is perforated at a particular place with reference to a zone within a formation. Such a check on measurements may be had by placing a reference marker at a point known with respect to the electrical log of the borehole. That point is usually chosen to be in proximity to the 'One to be perforated. Thus, only short in depth measurements are made and any inaccuracy becomes very small and of minor importance' The use of reference markers located at fixed points predetermined in each zone where future operations are contemplated enables the operator to position any tool

Jan 1, 1948

By H. G. Doll, H. P. Schwede

This paper describes a method to provide identification of particular depths in a borehole through the use of radioactive markers. The correlation of a marker, placed in the wall of a borehole, with known points of the electrical log and with the casing collars in the cased hole permits accurate positioning of tools with respect to a formation, regardless of absolute depth. Such a process is particularly useful in gun perforation of a casing in a well. Technique and equipment are discussed and illustrated. Examples are given of practical application in the field. Introduction During the past decade the search for petroleum has increased the importance of testing zones at depths in wells which have become progressively deeper. The development of new techniques, such as electrical logging, has permitted the identification of producing formations which consist of comparatively thin strata. When thin beds are to be produced at great depths, the problem of positioning tools accurately to place the well in production becomes acute.l Continuous consideration is being given in the petroleum industry towards the improvement of depth measurements in a borehole. The accuracy in absolute depth measurements, whether made in an open or cased hole, whether determined by a cable or a drill pipe, depends upon a number of factors, such as tension, temperature, and calibration. For example, the effects of tension from the weight of 10,000 ft of drill pipe and the thermal expansion of this length . of pipe, where its average temperature has increased SO"', will Produce an elongation as much as 8 ft.2 The effects Of such factors can be minimized through the use of care in depth measurements, the application of corrections based on experience, and continuous calibration or checking. The fact that different methods and different tools are used to determine the depths of formations in wells will sometimes give rise to a difference between measurements. It is evident that an important requirement in a well is the ability to locate at will any subsurface point. While absolute depth measurements have ion in recent years, it is reassuring to have other means to verify, for example, that a casing is perforated at a particular place with reference to a zone within a formation. Such a check on measurements may be had by placing a reference marker at a point known with respect to the electrical log of the borehole. That point is usually chosen to be in proximity to the 'One to be perforated. Thus, only short in depth measurements are made and any inaccuracy becomes very small and of minor importance' The use of reference markers located at fixed points predetermined in each zone where future operations are contemplated enables the operator to position any tool

Jan 1, 1948