Search Documents

John Birkinbine, Philadelphia, Pa.: We have in the Institute two Dudleys—Dr. Charles B. Dudley, who has so thoroughly studied the chemical composition and physical behavior of rail-steel, and Dr. P. H. Dudley, whose investigations and

Jan 1, 1900

By AIME AIME

DESPITE the fact that its membership is spread over every continent of the globe, the Petroleum Division was able to report a very substantial attendance at its meetings. Careful planning on the part of its chairman, J. B. Urnpleby, and his associates resulted in the presentation of a program that was of timely interest -and led to discussions that will unquestionably prove to be of major value to the petroleum engineer and to the oil industry in general. Scheduling of meetings so as to avoid all conflicts made it possible to obtain a higher average attendance at the several sessions* than in previous years, and gave everyone a chance to hear all of the papers that he was interested in. The chairmen of the various meetings are to be congratulated especially for their skill in handling them so that at .no time was there the least indication of lagging interest.

Jan 1, 1930

[University of Alaska College, Alaska Mining Society TOM CHRISTENSON, President MARY ANN KISER, Secretary H. G. WILCOX, Faculty Sponsor WM. FACKLER, Counselor University of California Berkeley, California Mining Association JOHN W. COOK, President LORETTA A. RICHTER, Secretary W. S. WEEKS, Faculty Sponsor]

Jan 1, 1946

By S. WHINERP

(Cleveland Meeting, October, 1912.) I AM indebted to L. E. Bryant, of Danville, Ky., President of the Virginia Mining Co., operating coal-mines in Scott county, Tenn., for the following information relating to the existence of the Clinton iron-ore under the NW. slope of the Cumberland Plateau in Kentucky and Tennessee. During the past 15 years quite an important oil-field has been developed in a region having Wayne county, Ky., as its center, and a large number of wells have been drilled in that and adjacent territory in the search for oil. Many of' these wells have been carried to considerable depths below the recognized oil-bearing horizon, and one of them was drilled by Mr. Bryant at Pine Knot, a station on the Cincinnati, New Orleans & Texas Pacific railroad, a few miles north of the point where that road crosses the Kentucky-Tennessee State-line. The elevation of the surface at the crossing is about 1,400 ft. above sea-level. The railroad is located on the dividing ridge between the Cumberland river and Big South Fork. At a depth of 1,720 ft. below the surface the drill reached and passed through a formation which the drillers called " red rock," but which Mr. Bryant classified as Clinton iron-ore, as its geological position corresponded to that formation. The ore at this point was 6 ft. thick and appeared to be of uniform quality throughout. An analysis of the drillings gave : Fe, 33; Mn, 0.25; Si02? 3 ; Al203, 2 ; CaO, 13; MgO, 7 ; P,05, 0.333 per cent. ; S, trace. This analysis seems to confirm the belief that the ore is Clinton, and that it is of a quality equal to the average of the deep or unbleached Clinton ores in Tennessee and Alabama. This discovery led Mr. Bryant to make further examinations and inquiries, and he found that the stratum called " red rock " by the drillers had been passed through and noted in the great majority of the wells carried down to the same geological hori-

Oct 1, 1912

By Arthur Connolly

WHEN scientific literature was lacking or meager, research necessarily meant laboratory investigation above all else. Today, scientific literature has attained tremendous proportions, and the volume increases at a much faster rate than it is digested and efficiently utilized. For that reason the present-day research worker should spend much more time in the library, and correspondingly less in the laboratory, than is the general custom. Library research would overcome two serious errors often made by scientists: duplication of work described completely and failure to appreciate inventions described almost verbatim in the literature. To emphasize these failings that often occur in present-day research, consider a hypothetical scientist as he conducts his search from inception to the stage where it is made available to the public by patent or other publication.

Jan 1, 1942

By Ta M. Li

Expanded mine-mill capacity and greater operating flexibility are part of the dramatic changes taking place in the Tennessee mining operations of Asarco, Inc. Climaxed by the recent start-up of the $6.3 million Young mill in September 1975, Asarco has pushed Tennessee back into number one position as the leading zinc mining state. Furthermore, start-up of the Young mill is expected to insure a much-needed and continuing domestic zinc supply, at a time when US mines can only supply one-half of 1975 domestic consumption.

Jan 5, 1976

By L. D. Jaffe, D. C. Buffum, F. L. Carr, M. Goldman

IN an earlier investigation by Jaffe and Buffum,' a time-temperature transformation diagram for isothermal temper embrittlement of an SAE 3140 steel showed some suggestion of two overlapping "noses." These authors mentioned, as a possible explanation, that their specimens embrittled at 525°C were slightly softer than expected, perhaps because of some slight unknown variation in tempering treatment. Because a double nose would be of considerable importance in elucidating the mechanism of the temper brittleness reaction,' it appeared worthwhile to redetermine the portion of the diagram near 525°C. The same heat of SAE 3140 steel was used as in the previous work, and experimental procedures were the same.' Blanks were austenitized 1 hr at 900°C, water-quenched, tempered 1 hr at 675°C, and water-quenched. Groups were then embrittled isothermally at the temperatures and for the times shown in Table I, and water-quenched. For comparison, one series was tempered various times at 675°C, water-quenched, and given no further treatment. V-notched Charpy impact specimens machined from the blanks were tested over a range of temperatures. Energy absorption and percentage of fibrous fracture were plotted vs test temperature for each group, utilizing both the new data and those for the same treatment obtained in the earlier work,' except that the earlier data at 525°C were discarded.* are given in Table I. After a small correction (-0.28°C/BHN) for the variation of hardness" from Rockwell C24, the transition temperatures were plotted against embrittling time for each embrittling temperature, using the data of Table I for the range of treatments covered there, and using previous dataL for other treatments. By cross-plotting, Fig. 1 was finally obtained. It appears from this figure that if there are two noses to the time-temperature-transformation diagram for isothermal temper embrittlement of SAE 3140 steel, the upper nose must lie above 575°C. As interest had been primarily in the region near 525°C, a thorough study of embrittlement above 575°C was not made. Fig. 1 shows that such a study is needed, especially since preliminary measurements at the tempering temperature of 675°C reveal much more rapid embrittlement than would be expected from the data at lower temperatures. The transition temperature increased, approximately, as the logarithm of the tempering time (about 81/2°C, after correction for hardness, for each doubling of the time).& Since three tensile specimens tempered 240 hr at 675°C and water-quenched had an average yield-tensile ratio of 0.844, with 70.7 pct reduction of area, it is assumed1 that the tempering temperature is not above Ae1. The omission of a quench-and-reheat operation below Ae1, for the groups tempered at 675°C, as compared to groups embrittled at lower temperatures, should not affect results." More detailed investigation of embrittlement above 575°C is now under way.

Jan 1, 1954

By Ednlund D. North

Discussion of the paper of Edmund D. North, presented at the Spokane meeting, September, 1909, and published in Bulletin No. 37, January, 1910, pp. 21 to 25. A. SCOTT REID, London, Eng. (communication to the Secretary*) :-As a constructor of several glass mine-models, I have read with much interest the description of the model of the Montana-Tonopah mine-workings by Edmund D. North. As an interchange of ideas and experience is always an advantage, and in view of the fact that such models are coming more and more into vogue, perhaps the following remarks on this subject may prove of interest to mining engineers generally and to Mr. North particularly. In the model of the Waihi gold-mine, New Zealand, which I constructed, a dust-proof case is used. The top, bottom, front, and two ends are of glass; the back only is of wood, painted a dull white, against which the mine-workings show very distinctly. Each mine-level is represented by a horizontal sheet of glass, supported on metal runners fixed to the uprights at each end of the case, in a manner similar to that described by Mr. North. The corner uprights are strengthened by having a metal band screwed to the inside face of each, to which the metal runners or supports for the sheets of glass are screwed in turn. The reason for having this additional strength is that as the mine is developed in depth, and fresh levels are opened, the increasing weight of the glass sheets, added to the model, caused the unsupported wooden uprights to bend slightly, so that the glass sheets-did not fit in with the desired nicety, and co-ordination was, to a considerable extent, lost. Strengthening the uprights in this manner is not important in models of mines in which only a few levels have been opened, or when the sheets of glass are small, but in the Waihi model there are 15 sheets of glass to be supported, and more to be added as development proceeds, and the weight is considerable.

May 1, 1910

By Robert W. Hunt

The first pump of this character, made by H. R. Worthington, and, so far as the writer is informed, the first and only one of this kind ever constructed, is now in daily use in the above-named works. The water-pressure necessary for the working of the hydraulic machinery of this plant had been supplied, up to the time of the building of this pump, by two Worthington Duplex High Pressure Pumps, having steam-cylinders of 20 inches diameter and 12-inch stroke, with water-plungers of 71/2 inches diameter; eight inlet and eight outlet valves of 24 inches diameter, and pumping into a 6-inch pipe. These pumps required a large amount of steam, and, in consequence of the various additions to their duty, their capacity became far short of the work required. In preference to putting in another engine of the same class, it was decided to accept Mr. Worthington's proposition to build the compound one under description, he guaranteeing that it should be equal to the demands of the works, and at the same time cause a saving of from 5 to 6 tons of coal per day from the amount required to run the two old pumps. The new engine has been in operation about one month, and so far has exceeded the most sanguine expectations. It consists of two high-pressure cylinders of 21 inches and two low-pressure ones of 363/8 inches diameter, by 36-inch stroke, with water-plungers of 961/2 inches diameter. There are two air-pumps of 20 inches diameter by 18-inch stroke; the condenser being 24 inches diameter by 60 inches high. Both cylinders are jacketed with wood and felt, and the low-pressure cylinder also with live steam. The high and low pressure steamcylinders are in line and immediately adjoining each other, while the inconveniences attending an internal stuffing-box are avoided by having two piston-rods for each of the low-pressure cylinders, running through stuffing-boxes on the outside of the smaller high-pressure ones. The steam-valves are very ingeniously designed balanced

By G. B. Pryde, R. M. Magraw

In laying out a new mine, provision should be made for the ultimate recovery of as much coal in any given bed as is consistent with safety and economic mining. Though each mining district, if not each individual mine, has problems that make the adoption of any hard and fast rule impossible, certain basic principles are adapted to practically all conditions. One of the most vital is the provision for barrier pillars of ample dimensions to protect all haulage and permanent airways during the life of the property. Where conditions permit, room or butt entries should be driven on the strike or slightly to the rise, and rooms turned at right angles to these entries. The width of rooms and room pillars is governed by conditions prevailing in the mines under consideration. A safe rule is: In advancing, extract not more than 25 to 35 per cent. of the entire seam; in exceptionally thick seams, considerably less than 25 per cent. should be taken. Rooms usually vary in length from 250 to 350 ft. (76 to 106 m.) with a barrier pillar of not less than 80 ft. between the last crosscut. in rooms and the back entry of the level above. All entries, rooms, and entry-and-room crosscuts should be driven .on sights and room crosscuts should be driven at, right angles to the direction of the rooms. In mines under excessively heavy cover or where roof conditions are bad, rooms should be driven narrow and a barrier pillar left at every fifth to tenth room. This barrier should be of such dimensions that one or more rooms, with pillars of usual dimensions, may be turned through it when the barrier is no longer required. Two of the advantages of such a barrier are the protection of the panel against peaking of roof load during pillar extraction and the easy closing of the entry in case of fire. Where economic conditions permit, it is preferable to follow the retreating panel system of mining. In the case of coal that outcrops, and even in cases where no outcrop is exposed, it is preferable to commence pillar extracting on the high side of the mine. Where the retreating

Jan 1, 1922

By C. R. Boyd

The region to which I have the pleasure of calling your attention, though limited in area, is remarkable for the quantity and purity of its mineral deposits, and in these respects it would be difficult to find its equal anywhere. IRON ORES. The red and brown hematites, pipe ore, and semi-magnetites, from which is made in charcoal furnaces the highest quality of iron for car-wheels, extend through the counties of Giles, Montgomery, Pulaski, Wythe, Smyth, Washington, Bland, Tazewell, Russell, Scott, Lee, Floyd, Carroll, and Grayson, Virginia, and run over into Ashe County, North Carolina. One locality of semi-magnetite, in the centre of the great Giles County basin, has in sight, by actual measurement, 50,000 tons of ore, which, according to Prof. Fesquet, contains 69.74 per cent. of iron and no phosphorus. In the great brown-ore belt, which passes through the counties of Montgomery, Pulaski, Wythe, Smyth, and Washington, there is an extraordinary deposit of more than a million tons. A small section of this very long vein, on Cripple Creek, in the County of Wythe, yields an ore which, analyzed by Mr. James Aumann, gave the following results: Metallic iron,........58.15 Water,.........12 96 Alumina,........2.32 Silica,.........1.09 Phosphorus,.. none. At one point towards the western end of Red Land Mountain, in Pulaski County, New River section, I measured a body of ore in this belt which will yield, to a depth of 150 feet, over 8,000,000 tons, and the deposit extends far below the 150 feet measured at the upper part. Again, at Rich Hill, near the mouth of Reed Island Creek, these veins show extraordinary surface development, giving an ore of very great purity. At numerous places, also, in the counties of Giles, Bland, Tazewell, Russell, Scott, Wise, and Lee, these brown and red iron ores are exposed in such vast quantities as to baffle both description and measurement. That of Chestnut Flat, in Giles County, back or west of the Angel's Rest Mountain, is an easily reducible ore, blood-red when crushed, of which there are fully 300,000 tons in sight. Its analysis is as follows :

Jan 1, 1880

By H. J. Rahilly

Mine fires, in the Butte district, have been a source of trouble and expense for the past thirty years, for while the actual fire area in most of the mines has been comparatively small, the handling of the gas has generally been a much larger problem than the actual putting out of the fire. The chief causes of these fires have been: Defective electrical equipment, incendiarism or carelessness, and spontaneous combustion. While fires from the first two causes have been numerous, they have generally been discovered and extinguished before they became very serious. Spontaneous combustion has been the cause of most of the large fires. Sufficient heat has been generated by ground movement, high rock temperatures, and decomposition to set fire to inflammable materials (tarred ropes, canvas, dry timber, manure, and hay) left in the gobs some years ago. Also, the heat resulting from the oxidation of the fine broken sulfide ore is sometimes sufficient to set fire to the timbers. In 1906, a fire was discovered on the 1100-ft. level of the Minnie Healy mine about 400 ft. (122 m.) west of the Minnie Healy shaft, which presumably originated, in one of the upper levels, from spontaneous combustion. The fire was walled off by concrete bulkheads and a pillar of ground 100 ft. (30 m.) thick was left below and mining resumed underneath. During subsequent operations, this pillar became cracked and broken and the fire passed into the new workings. It travelled downward and spread rapidly until, in 1917, it had become necessary to wall off portions of the Tramway, Leonard, and West Colusa mines on the 1300, 1400, 1500, 1600, 1800, 1900, and 2000-ft. levels, and the tops of the 2200-ft. raises were sealed. The fire area now consists roughly of a block 1000 by 1200 ft. and from the 600-ft. to the 2200-ft. level. This block is composed largely of a series of parallel northwest-southeast nearly vertical veins and stringers that form a large orebody, with no well-defined walls but badly fractured and faulted, and known locally as "horsetail ore." These veins, or orebodies, are mined by the square-set or the rill method.

Jan 1, 1923

By Earl Oliver

The term oil property, in this discussion, includes any type of easement or grant under which petroleum might be produced; it ranges from the mere right to drill on undeveloped wildcat acreage up to a fully developed oil property. The values of an oil property, as thus defined, vary widely according to the use for which it is intended, whether it is from the viewpoint of the speculator, the fraudulent stock promoter, the refiner and pipe-line owner, or the oil producer. The market value of a property is usually a combination of some two or more of these influences, and occasionally a combination of all of them, but we prefer to treat each viewpoint as distinct from the others, allowing the reader to make his own combination in such proportions as his inclination and property seem to require. This paper will treat the subject from the viewpoint of the oil producer. However, the other influences have such bearing on the cost of property to the producer and on the price he might obtain by its sale as to warrant brief discussion of them. Speculation, particularly lease speculation, is a parasitic growth on the oil industry, healthy enough, but of no economic value. The class of property usually dealt in for this purpose is the undeveloped lease. Its speculative value may have some relation to its probable productive value, but most frequently this value is the product of temporary excitement due to local development. The lease speculator, seeking out the trend of development or securing early information regarding a proposed test or a new discovery, immediately secures leases whose market value will be increased when the existence of such development becomes more widely known. His profits are purely unearned increment. Not proposing to spend money in exploration, he can afford to compete in purchase with the operator, who, in addition to bonus paid, must spend large sums in testing out his own acreage and that of the nearby speculator as well. It has a tendency to compel unduly high bonuses. The so-called "checker-board1' system of leasing wildcat acreage by the larger companies is on the same principle of attempting to secure the

Jan 1, 1921

By H. J. Rahilly

Mine fires, in the Butte district, have been a source of trouble and expense for the past thirty years, for while the actual fire area in most of the mines has been comparatively small, the handling of the gas has generally been a much larger problem than the actual putting out of the fire. The chief causes of these fires have been: Defective electrical equipment, incendiarism or carelessness, and spontaneous combustion. While fires from the first two causes have been numerous, they have generally been discovered and extinguished before they became very serious. Spontaneous combustion has been the cause of most of the large fires. Sufficient heat has been generated by ground movement, high rock temperatures, and decomposition to set fire to inflammable materials (tarred ropes, canvas, dry timber, manure, and hay) left in the gobs some years ago. Also, the heat resulting from the oxidation of the fine broken sulfide ore is sometimes sufficient to set fire to the timbers. In 1906, a fire was discovered on the 1100-ft. level of the Minnie Healy mine about 400 ft. (122 m.) west of the Minnie Healy shaft, which presumably originated, in one of the upper levels, from spontaneous combustion. The fire was walled off by concrete bulkheads and a pillar of ground 100 ft. (30 m.) thick was left below and mining resumed underneath. During subsequent operations, this pillar became cracked and broken and the fire passed into the new workings. It travelled downward and spread rapidly until, in 1917, it had become necessary to wall off portions of the Tramway, Leonard, and West Colusa mines on the 1300, 1400, 1500, 1600, 1800, 1900, and 2000-ft. levels, and the tops of the 2200-ft. raises were sealed. The fire area now consists roughly of a block 1000 by 1200 ft. and from the 600-ft. to the 2200-ft. level. This block is composed largely of a series of parallel northwest-southeast nearly vertical veins and stringers that form a large orebody, with no well-defined walls but badly fractured and faulted, and known locally as "horsetail ore." These veins, or orebodies, are mined by the square-set or the rill method.

Jan 1, 1923

By L. C. Snider

During the past few years a number of large and highly productive oil fields have been discovered in the United States. The immediate oversupply which has resulted, together with the circumstances under which the new fields have been operated, has created exaggerated impressions of the importance and magnitude of these fields. Statements as to the many years during which individual fields could supply the entire demand of certain areas, as to the overwhelming effect of these fields on the industry, and as to their greater size compared with any of the older fields have become so common as to attract little attention. For example, East Texas is commonly considered as the "greatest oil field" and a review of the development of the field for 1931 is so headed in one of the leading trade journals.' East Texas is unquestionably a very great oil field. However, some students of the field have estimated its ultimate recovery at about one billion barrels, and the Bradford field discovered in 1875 is also estimated, by competent engineers, to have about a billion barrels still recoverable by water drive, in addition to more than 300,000,-000 bbl. it has already produced. If East Texas should produce the two or three billion barrels assigned to it by more optimistic estimators, it will, though considerably greater than Bradford, still fall far short of it in importance to the industry. A reasonable doubt also exists as to whether East Texas will exceed the Midway-Sunset field which has produced about 720,000,000 bbl. and still has important reserves. Again, in importance to the industry, Midway-Sunset has been greater than East Texas can ever be. Relative Importance of Oil Fields The principal purpose of this study is to compare, on the basis of their importance to the industry, a considerable number of the major fields which have been developed in the United States. Some remarks are also made as to the estimates of reserves in certain fields now in course of development, since the writer believes that the conditions under which these fields are operated lead to estimates of recoverable reserves which

Jan 1, 1933

This fund was established in 1929 for support of research and especially refers to non-ferrous mining and metallurgy. It is administered under the Board by a committee consisting of the President and Secretary and three members selected by the Board. HOWE MEMORIAL LECTURE The Howe Memorial Lecture, in memory of Henry Marion Howe, Past President of the Institute, was authorized in April, 1923, as an annual address to be delivered by invitation under the auspices of the Institute by an individual of recognized and outstanding attainment in the science and practice of iron and steel metallurgy or metallography, chosen by the Board of Directors upon recommendation of the Iron and Steel Division. The following were the Howe lectarers for the years indicated: Albert Sauveur—1924 Bradley Stoughton—1927 John A. Mathews—1925 Henry D. Hibbard—1928 William Campbell—1926 John Howe Hall.—1929 JOINT ACTIVITIES 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 Society This is a corporation organized by the American Institute of Mining Engineers, American Society of Mechanical Engineers, and the American lnstitute of Electrical Engineers, to hold the title and administer the property at 29 West 39th St. In 1916, the American Society of Civil Engineers was admitted, and each society now has an equal one-fourth interest in the ownership, occupancy, and administration of the building. . The cost of this property has been over two million dollars. A. I. M. E. representatives are: Arthur S. Dwight, John V. N. Dorr and H. A. Guess. Alfred U. Flinn, Secretary, 29 West 39th St., New York City. Engineering Foundation This is a fund established by the United Engineering Society in 1915 with a gift of $200,000 from Ambrose Swasey. Subsequent gifts had increased the fund to about $620,000 on March 1, 1929. The income of the fund is used to further research in science and engineering and to advance the profession of engineering and the good of mankind. A research project in alloys of iron is being conducted in

Jan 1, 1929

"In the spring of 1927, six members of the American Institute of Mining and Metallurgical Engineers met for dinner at the Chemists' Club in New York to discuss the possibility of setting up a committee within the Institute to further the current interest in the science of steelmaking. Attention to this subject had been crystallized by a symposium held by the Faraday Society in 1925. After a prolonged discussion, ranging from thermodynamics to slag conditioning, it was decided to approach the Institute with the request that a standing committee on "The Physical Chemistry of Steel Making" be set up. This committee proposed to promote scientific and practical papers on the subject, and was designed to cooperate with the Open Hearth Committee of the Institute in bringing scientific developments to the attention of open-hearth operators throughout the country. . . . "As the life of the [Physical Chemistry of Steelmaking] Committee lengthened and general interest in the technical phases of steelmaking grew, it .became evident that there was a distinct need for a book that might serve the open-hearth interests to better advantage than standard texts whose scope is necessarily wide and whose detailed exposition of the open-hearth process is, therefore, somewhat limited. With this thought in mind, the Committee, after some years of consideration and debate, embarked on the venture of writing a manuscript on 'Basic Open Hearth Steelmaking'." The foregoing paragraphs, taken from the introduction by C. H. Herty, Jr. to the first edition, well describe the circum- stances which led to the publication of “Basic Open Hearth Steelmaking” in the spring of 1944. The book consisted of nine- teen chapters contributed by twenty-three authors and edited by the staff of Alloys of Iron Research and T. S. Washburn, H; M. Larsen, and J. S. Marsh with Frank T. Sisco as consulting editor. The Engineering Foundation and the Open Hearth Steel Committee of the Iron and Steel Division, AIME, made financial grants; steel companies and other organizations supported the publication by contributing time and expenses of staff members in their capacity as authors or editors. The volume was sponsored by the Seeley W. Mudd Memorial Fund and appeared under the

Jan 1, 1964

JOSEPH DANIELS, Seattle; Wash. (communication to the Secretary*). Mine models are of great value to the student and to the layman in visualizing underground conditions, and, in a measure, should be just as much a part of the equipment of a mining school as sets of ore specimens, catalogs, or drawings. The chief drawback, as Professor Stock has indicated, is the time and cost of making them. The greatest good in the development of the model comes to the person who makes it, and I have often wondered whether it might not be possible to have each student make one model during his undergraduate career. At the University of Washington we have been collecting sets of mine timbers, made of 6 by 6-in. lumber, illustrating shaft, level, and stope timbering. This work has been done by freshmen. Perhaps each educational institution could specialize in the creation of a certain type of model and exchange its product for that of another school, just as we now do with ore collections. In this way we could build up good museums at a relatively low cost. JOHN R. CHAMBERLIN, New York, N. Y. (communication to the Secretary?).-The type of model described by Professor Stoek is admirably suited to exhibits of coal mining in horizontal veins, and fulfills perfectly the three purposes mentioned. As an educational illustration in colleges, especially when the students themselves build the model under the direction of their instructors, it is of the highest value; and as each condition in mining requires special methods to depict properly in a model, the student is compelled to exercise considerable inventive resource to construct a true representation, stimulating the imagination and interest in his subject. Models built for exhibits in lawsuits are usually constructed to show prominently some particular feature of vein formation or geology, or the relation of underground workings to surface property lines, and as such their use is invaluable to the successful litigant. When the litigation is ended, it is natural that the model should be relegated to the basement and frequently destroyed, as data on underground workings are often considered of a private character by the operators; and it is

Jan 10, 1917

By J. T. Duce

There were no important changes in the producing situation in Colombia in 1930, because the emergency bill passed by the Colombian Congress in 1927 is still in effect, and therefore no change has taken place in the law governing petroleum. At the close of 1930 the Colombian Congress began to consider a new petroleum bill. This measure is an improvement on the preceding bills which had been the subject of so much debate in the Congress. However, it cannot by any means be regarded as perfect, and a number of criticisms may be justly leveled at it. The most substantial one probably is that the royalties on public lands, and the taxes on private lands, while apparently low, are deliverable at seaboard, or payable based on seaboard price at the option of the government. If the government exercises its option to take the oil at the mouth of the well, the cost of the transportation figured back into oil is also deliverable to the government. This phase of the law has the effect of making seemingly low royalties a burden on the operator. The fact that taxes on private properties are deliverable in kind is also an unusual provision for which there is no good precedent. The pipe line provisions are also noteworthy, and the government has authority to fix rates and also to deny permits to construct pipe lines for reasons affecting national economy. There are also clauses enforcing unit operation on both public and private lands, and collecting a tax of 1 c. per 1000 ft. of gas wasted. It remains to be seen whether this bill will be enacted, or whether it will be substantially modified. This much may be said, however, that unless it is modified, it will defeat its own purpose; i. e., promotion of petroleum development in Colombia. Company Activities The South American Gulf Oil Co. shut down its operations during the year, and now employs only watchmen at its camps, Las Monas and El Tigre. The Standard Oil Co. of California continued operations on the Coast at Repelon and Gualapa. At the close of the year Repelon

Jan 1, 1931

By W. O. Hotchkiss

IN CONSIDERING the question of mining methods the possible rate of production deserves much more attention than it often receives. Hoover's theorem that, in order to show the greatest profit, an orebody should be worked out in the shortest practicable time, should be better known. The author recently' obtained detailed statements of costs from iron-mine superintendents of the Lake Superior district. In discussing these, the effect of rate of mining on cost of production was considered and detailed estimates were made. The methods by which these estimates were made and the way in which they were presented are here described to illustrate the importance of this factor in mining operations. The saving due to lower costs is not the only factor that should be considered. The greater profit per ton is of much importance but of equal importance are the greater profit per ton that will be made on a greater number of tons per year, and the fact that the total profit will be received in a shorter; period. This last makes a great difference in the present value of a property, by shortening the period of discount on future profits. Another item of importance to those operating a number of mines is that the tonnage needed to supply the market can be obtained most profitably by operating the smallest number of mines that will supply the amount required when each is worked to maximum capacity. In the Lake Superior iron district there are many grades of ore, and the requirements for each are known. If the demand for a certain grade can be supplied from mines now operating, the development and mining of a new orebody of the same grade must result in lower rates of production and lower profits to all mines producing this grade. If a company is mining the same grade of ore from three mines when it can supply its needs by operating only two, by operating only two it can obtain the greatest profit. Royalty rates, lease terms, and other considerations modify this general statement, but if all three properties

Jan 5, 1922