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By H. De Cizancourt

The Pechelbronn (Alsace) field is the only important French producing field. During 1934, development was carried on as in previous years. The total output of this field reached 553,575 bbl. in 1934, showing a slight decrease from the 1933 figures. Of the total, 315,000 bbl. (56 per cent) was extracted by drilling, while 238,875 bbl. (46 per cent) was obtained by means of shafts and galleries. Exploration of deep Jurassic and Triassic horizons was still in progress at the end of 1934. A deep well reached the Upper Triassic at a depth of 34 m. (2736 ft.). (Information kindly supplied by M. S. Mena, Directeur Technique.) As mentioned before, the small Gabian field (Herault) is gradually being exhausted. No drilling operations were undertaken in 1934, the small production being restricted to the pumping of old wells. Two exploration wells, noted as "drilling" at the end of 1933, were completed in 1934; viz., Lavelanet (Ariége) at 3785 ft. and Santenay (Niévre) at 2578 feet. French Possessions Algeria.—No drilling at Tliouanet. Out of a total of 100 wells drilled in the area, only 8 are still producing. No exploration work is reported during 1934 in Algeria. Tunisia.—Two wells completed; one well drilling at the end of 1934. A total of 11 wells is reported to have been drilled before the beginning of 1935; out of these, 8 were completed before the present program was begun. Morocco.—Exploration work progressed actively last year. The outstanding event was the coming in of Ts. 26 well at 1243 ft. This well took fire, therefore great difficulties were encountered in the accurate measurement of initial production; the figure of 1500 bbl. of oil given here is a near estimate. Oil flowed accompanied by a great amount of water. The apparent decrease of drilling operations in 1934 is explained by the increase in field activities after the results of Ts. 26 were known;

Jan 1, 1935

Organization Place Date 1919 American Society of Civil Engineers..: Twin Cities, Minn. June 17-20 American Society of Mechanical Engineers Detroit, Mich. June 17-20 American Institute of Chemical Engineers Boston, Mass. June 18-21 American Drop. Forge Association Pittsburgh, Pa June 19-21 American Institute of Electrical Engineers Lake Placid, N. Y. June 24-27 American Society for Testing Materials Atlantic City, N. J. June 24-27 Society for Prom. of Engng. Education Baltimore, Md. June 25-28 American Chemical Society Philadelpia, Pa. Sept. 2-6 National Assn. of Stationary Engineers Huntington, W. Va. Sept. 8 American Peat Society.. Minneapolis, Minn. Sept. 22-24 American Iron; Steel Electrical Engineers St. Louis, Mo. Sept. 22-26 American Institute of Min. and Met. Engineers, Chicago, Ill. Sept. 22-27

Jan 6, 1919

The following record of the important responsibilities already shouldered by Dr. Ricketts will give some indication of the trust and confidence reposed in him by his colleagues. The Institute is to be congratulated that a man who is already so much engaged should be willing to assume the further responsibility of guiding the Institute's Ship of state during the ensuing year. Louis Davidson Ricketts, who is brother of Professor Palmer or Chamberlaine Ricketts, President of Rensselaer Polytechnic Institute, was born at Elkton, Md., Dec. 19. 1859, was graduated from Princeton University in 1881 with the degree, Bachelor of Science, chosen a Fellow in Chemistry and W. S. Ward Fellow in Economic Geology, and after two years' study given the degree Doctor of Science. Following the completion of Iris work at Princeton, Dr. Ricketts went to Colorado and started to work as a mine surveyor. For the 15 years following, his time was chiefly occupied in reconnaissance work, geological work and mine examination. From 1887 to 1890 Dr. Ricketts was Geologist for Wyoming, and at, the end of that period transferred his operations to the Southwest. where he has since been steadily engaged in large mining projects. He was identified with the acquisition of the property now owned by the Moctezuma Copper Co., a , subsidiary of Phelps, Dodge & Co., at Nacozari, Sonora, Mex. From 1899 to 1901 he was General Manager of the property and during his administration the concentrator and reduction works were completed and the mines put on a dividend-paying basis

Jan 3, 1916

By H. B. Charmbury, D. R. Mitchell

Everyone in the coal industry from top management to the preparation engineer is vitally interterested in recovering as much salable coal as possible from the run-of-mine product. Coal losses from a preparation plant occur in the solid refuse material being discharged from the plant and in the bleed-off slurry from the water circuit. The refuse is generally hauled from the plant in solid form by trucks, conveyors, or aerial trams to the refuse or culm banks or it may be crushed and transported by hydraulic methods to refuse ponds or dams. The loss of coal in refuse material and the extent of this problem has been covered in another paver.' The loss of salable coal in the plant bleed-off slurry is one of the water circuit problems in coal preparation plants. Slurries originate at various places in the processing circuits and are usually disposed of by transportation to waste ponds known as slurry ponds. Even though the combustible material discharged as slurry and refuse from the plant is labeled a loss, the loss must only be considered temporary. There is a tendency at the present time to examine refuse and slurry losses and to reprocess these materials to recover valuable coal. Slurries from eight bituminous coal preparation plants in central and western Pennsylvania have been sampled and examined to determine the amount of recoverable coal in each. Examinations of the samples were made to determine the tons per hour of solids and the gallons per minute of water in the slurry; the size, ash, and sulfur analyses of the solids; and the sink-float characteristics of the larger solids. The extreme fines (—325 mesh material) from one of the samples has been examined further to determine the micron size fractions as well as the ash and sulfur content of the micron sizes. Collection of the Samples: Field trips were made to each of the plants where samples were obtained and discussions held with the preparation engineer prior to sampling. The flowsheet of the plant operation was studied and a time-period selected to obtain a representative sample. At least 20 1-gal samples of total plant bleed-off suspensions were collected at each plant in increments over designated periods belived to be typical of the plant flow Three of the samples were obtained from plants in the Pittsburgh area. Each plant supplied information on the capacity, operating time, type of cleaning equipment used, water and material balances, and auxiliary equipment. From the time required to collect given amounts of slurry and from the amount of solids in the slurry, total solids discharges from the plant were calculated and compared with the plant flow. Ash and sulfur analyses of the total solids were also checked, at some plants, with company figures. In all cases where checks could be made there was reasonable agreement between company figures and those reported here. Analysis of the Slurries: Representative fractions of properly agitated samples were examined in the laboratory to determine the specific gravities of the slurries. The solids and water were separated by filtration to check the weight of each so that the percent of solids in the pulp could be determined. From the resulting data, presented in Table I, it may be seen that the percent solids in the slurries ranges from 2.8 to 39.0 and the amount of solids from 2.61 to 45.61 tph. Size Analysis of Solids: Representative fractions of the slurries were permitted to settle and the clear water was removed by siphoning. The solids were then wet-screened at 28, 35, 48, 65, 100, 150, 200 and 325 mesh. Results of the size analyses are presented in Table 11. These results indicate the extreme variation of sizes and in most cases the degree of fineness of the solids. The amount of —325 mesh ranges from 22.5 to 84.5 pct and the amount of+200 mesh from 8.3 to 69.1 pct.

Jan 1, 1961

By A. W. Asman

The problem of balanced design in a belt conveyor has been under constant study. Increased use of this method of transport in recent years has stimulated investigations. Conveyor belt, power transmission and other machinery should be adequate to perform the required service. All components of the belt conveyor should work as an efficient unit moving its load continuously between terminals. As part of a long term research project on belt conveyors, Hewitt-Robins established in 1954 a 2-year grant at Pennsylvania State University. Under terms of the grant, certain fundamental phenomena were to be studied. This work evolved a new concept in belt conveyor power determination based on the principle of belt tension. The Penn State contract furnished the foundation for later more detailed studies. From these most recent investigations, more specific factors were defined. In the final analysis, all of the data collected has been worthwhile in belt conveyor design. Units now operate over long distances at speeds of over 800 fpm. Long high lifts are commonplace. Where vertical or inclined shafts were the rule, belt conveyors receive first consideration. Although belt conveyors have moved forward rapidly, the future will see a tremendous gain in their use. The ideal test belt conveyor would be several thousand feet in length and have a maximum tension of at least 70,000 lb., Also, this conveyor should be horizontai and have a variable feed rate of more than one material. Data from such a field belt conveyor combined with laboratory information would permit accurate analysis. Since this type of conveyor was not available, many field locations were visited: An alternate would have been to erect a closed circuit system in the laboratory. Either method had limitations and the first was selected as having the best possibilities. Manufacturers of conveyor belting and machinery basically have been using the same horsepower formula. As more information became available from field installations, factors in the basic formula were modified. Practically all conveyors are designed today by adding together the horsepowers required to move the empty belt, move the load horizontally, and elevate the load. In selecting size of drive motor, the first two elements are relatively unimportant if the last is large. However, it is the combination of

Jan 1, 1961

By W. A. Gibson, A. D. Trujillo

The Santa Rita copper deposit first served as a source of native copper for Indian implements and weapons. In 1801 Santa Rita copper, trans- ported by mule train to Chihuahua, began to be used commercially for making coins. It was a small- scale operation made difficult by Indian raids, transportation costs and depletion of the higher grade ores. There was, moreover, no known method for economically extracting copper from the under- lying low grade sulfide ores. Originally, copper and copper oxide ores were mined by underground methods, but there was virtually no development of the deposit-which became United States territory after the Treaty of Guadalupe Hidalgo in 1848-for almost a hundred years. A number of small underground mines had been started during that time, but it was not until 1873 that all the principal claims were consolidated under one control.

Jan 1, 1966

By J. B. Fletcher

The Miami mine first started operations in 1910. For convenience, the history of the orebody can be divided into the following categories (Fig. 1): 1) 1910 to 1925: 24.4 million tons of high grade ore, mined by top slicing, sublevel caving, etc. 2) 1926 to 1954: 102 million tons of low grade ore, mined by block caving.

Jan 1, 1961

Jan 1, 1959

By L. H. Simons, H. H. Spain

I NT RODUCTION Theory indicates that linear water-floods should exhibit scaling and stabilization properties in both oil-wet and water-wet porous media'. Experimental verification of these proper-ties in oil-wet media was obtained some time ago', and more recently, Perkins', employing a high permeability unconsoli dated sand and a low oil-to-water viscosity ratio, has obtained flooding data in a water-wet medium which follow the pattern of scaling and stabilization. Also, Root and Calhoun3 have found similar trends in the displacement of gas by liquids from unconsolidated sands. In general, however, the experimen-tal evidence appears still somewhat conflicting since scaling and stabilization of water floods in water-wet media has not been observed in most of the studies to date'.".'. The purpose of this paper is to provide a more comprehensive picture of waterflood behavior in water-wet media and to corroborate the validity of the scaling and stabiliza-tion concepts. The need for differentiating between the intrinsic nature of water-oil displacements inside a porous medium and perturbating secondary end effects is discussed, pertinent experimental procedures are outlined and the results of flooding tests conducted at low and at high oil-to-water viscosity ratios on con- solidated, water-wet Alundum cores are analyzed. END EFFECTS IN WATER-WET MEDIA Outlet End Effects The peculiar feature of the outlet end effect in water-wet cores is that it not only results in an excessive wetting phase saturation at the outflow face,'.' but that it also retards the moment of water breakthrough: i.e., causes an undue delay in the appearance of water in the produced effluent. Conditions existing in a water-wet core when water first arrives at the outflow face are schematically shown in Fig. 1. At this flooding stage the saturation distribution, Fig. la, has not yet been distorted by the outlet end effect. A water-invaded pore at the outlet core face, opening into the oil-filled void space between the end of the core and the end plate of the flooding cell, is illustrated in Fig. lb. The curvature of the water-oil interface is concave toward the outlet, and the pressure on the water side of the interface is lower than on the oil side by an amount equal to a certain capillary pressure (Fig. lc). Before the water (of this particular pore) can be produced from the core, it is apparent that the pressure in the water phase must exceed that in the oil outside the core. Accordingly. when water first reaches the outlet face, it will not leave the core but will accumulate inside, and only oil will be produced. Eventually, as the water injection is continued. sufficient pressure is built up in the water to reverse the curvature of the interfaces in the outlet pores, and only then will water be produced from the core. This stage, illustrated in Fig. 2. corresponds to the conventional "water breakthrough" observed in flooding experiments. For purposes of discussion, it is convenient to distinguish between the flooding stage at which water first arrives at the outlet face of a core (Fig. 1) and the stage at which water is first produced from the core ( Fig. 2). The former will be referred to as "water arrival" and the latter water breakthrough. In oil-wet media

By R. A. Bosch, F. V. Lenel, G. S. Ansell

RECENTLY, Ansell and aenel' proposed a dislocation model to account for the yielding behavior of dispersion-strengthened alloys. The criterion for yielding used in this model was that yielding occurs when the shear stress due to arrays of piled-up dislocations fractures or plastically deforms the dispersed second-phase particles. Calculations based on this model predict that the yield strength, uysof a dispersion-strengthened alloy containing particles whose geometry permits them to be considered as straight, i.e. not curved, barriers to dislocations follows the relation where and are the shear moduli of the matrix and dispersed phase respectively, b is the Burger vector of a dislocation in the matrix, A is the mean free path between dispersed phase particles and C is a constant. This yield stress, ys, is closely approximated in polycrystalline alloys by the proportional limit. The offset yield stress, uoy, is the yield stress, uys, plus the increase of stress due to strain hardening in the offset strain increment. Previous investigation1 has shown that Eq. [I] describes the yielding behavior of several different dispersion-strengthened alloys as a function of the mean free path between dispersed phase particles at a constant temperature. The purpose of this investigation was to investigate the temperature dependence of the yielding behavior of dispersion-strengthened alloys. The alloys studied, MD2100 and MD5100, are SAP-type alloys containing flake shaped aluminum oxide particles dispersed in a matrix of commercial purity aluminum. The proportional limit and 0.2 pct offset stress of both of these alloys were determined as a function of temperature over the temperature range from -190" to 500 C. All tests were conducted on an Instron tensile testing machine. Stress was measured by means of the Instron load cell. Strain was measured by means of SR-4 strain gages attached to the tensile specimens. Stress sensitivity was 80 psi. Strain sensitivity was 2 x 10F Fig. 1 shows the values received for the proportional limit and 0.2 pct offset yield stress plotted as a function of homologous temperature for both the MD2100 and MD5100 alloys. Inspection of Eq. [I] shows that of the terms which determine the theoretically predicted yield stress, uy,, only the shear moduli have an appreciable temperature dependence. From Eq. [I] the yield stress at any temperature T, UT, may be predicted from the yield stress at any arbitrary reference temperature, in this case 25 OC, u25, by the relation where the subscripts T and 25 refer to the values of the property at test temperature and at 25"C, respectively. The temperature dependence of the yield stress predicted by Eq. 121, based on the observed value for the proportional limit at 25OC, is also shown in Fig. 1. In evaluating Eq. [2] the following data was used. The values for the shear modulus of

Jan 1, 1962

By J. Moore, D. Gault, R. V. Lugn

Impact of small projectiles with velocities between 0.9 and 7.3 km per sec on basalt produce craters chiefly by the ejection of fragments. Weight-size distributions of the ejecta are linear for part of the size range of the fragments. Cumulative weight-size distributions of the ejecta from different craters vary because of erratic formation of large fragments and a large percentage of ejecta below 0.1 mm. In the range of velocities studied, the crater depth is approximately proportional to the 0.75 power of velocity of the projectile. This relationship may represent a transition regime between the fluid impact regime and the undeformed projectile impact regime. The volumes per unit of projectile energy of the craters produced are comparable to those reported for lower speed projectile impact and drill bits. An experimental investigation of projectile impact on rock is being conducted jointly by the Ames Research Center of the National Aeronautics and Space Administration and the U.S. Geological Survey. Projectiles are launched with light-gas guns at the Ballistics Range of the Ames Research Center. The craters and ejecta produced in these experiments are being studied by the U.S. Geological Survey. Steel, aluminum and polyethylene projectiles weighing from 0.25 to 0.015 g were accelerated to velocities of 0.88 km per sec (2,900 fps) to 7.3 km per sec (24,000 fps) with a light-gas gun, using hydrogen as the propellant medium. Projectiles impacted the targets normal to plane rock surfaces in an atmosphere of air with a nominal pressure of 25 to 50 mm of mercury. The metal projectiles were mounted in supporting four-piece nylon sabots, which guided the projectiles down the launching tube. After launch, aerodynamic drag acted to separate the sabots from the projectiles. Impact velocities were determined with time measurements and spark photographs of the projectiles in flight. Ejecta were collected in lucite and aluminum containers placed around the target block. A small hole in the containers permitted projectile entry. Impact of projectiles of the size employed produced craters in the rock targets chiefly by ejection of fragments. The craters are small, roughly conical depressions with crushed and intensely fractured rock at the bottoms of the depressions. The ejecta are composed of pieces of the projectile and rock fragments ranging in size from a few tenths of a micron or less to several centimeters in maximum dimension. In this paper, the structural features of the craters, the weight-size distributions of the recovered ejecta, and crater depth and crater volume relationships are described. DESCRIPTION OF CRATERS Typical craters (Fig. 1) produced by experimental projectile impact in basalt are shallow, wide base

Jan 1, 1963

By Y. C. Liu

Both the habit plane of martensite and the orientation relationship between the matrix and martensite platelets of different habit planes have been investigated in binary titanium alloys with molybdenum, chromium, and iron. The effect of the mode of deformation on the martensite habit plane was studied. A micrograph of an exposed mar-tensite platelet is presented. IN the study of martensitic transformation in Ti-Mn alloys,' two martensite habit planes—{334), and {344)8—were reported. The {334), habit was also observed in unalloyed titanium upon transformation,' although there is disagreement with respect to the exact indices. The other habit plane, {344),, has not been reported in martensitic transformation in any other alloys. The present investigation was made to determine whether other binary titanium alloys with P-stabil-izing elements would exhibit a crystallography of transformation similar to that of Ti-Mn alloys. Furthermore, since martensite platelets can be induced by deformation under certain conditions, it was of interest to investigate whether the mode of deformation, compressive or tensile, would influence the formation of martensite platelets on a specific plane in an alloy system which possesses two martensite habit planes. Experimental Procedure The material used for the preparation of the binary alloys of iodide titanium with molybdenum, chromium, and iron had the following purities: 99.99 pct iodide titanium, 99.9 pct molybdenum, 99.423 pct chromium, and 99.9 pct iron. The compositions of alloys listed in this paper are in nominal weight percentage. All specimens used were prepared and treated according to the procedure described in reference 1, unless stated. For the subzero temperature treat,ment the following experimental schedule was followed. After specimens had undergone the grain-growth treatment, they were quenched into an ice-water bath and were then metallographically examined. In specimens of higher alloy content, no martensitic transformation was observed. In those in which mar-tensitic transformation did occur, only specimens in which the martensite platelets existed as fine needles in localized regions were used. All specimens were reannealed 17 hr at 1200°C, quenched into ice water. and the capsule was broken. They were held in the ice water for from 5 to 10 sec, then transferred to a liquid-argon bath. This stepped quenching procedure was found to be more efficient than direct quenching into liquid argon. In the latter case, as soon as the hot specimen was immersed in the liquid argon, a protective, insulating layer of argon gas formed, and the specimen continued to glow vividly in the bath for some time. In the study of the habit behavior of martensite produced by deformation, specimens were deformed at room temperature either by compression, tension, or rolling. Martensite habit planes were determined by the two-surface analysis procedure described in reference 1. A stereographic net of 153/4 in. diam was used throughout the investigation. The method for determining the orlentation relationship between martensite and the matrix follows that used by Greninger and Troiano.' A diamond-polishing table with its auxiliaries was used in order

Jan 1, 1957

By H. Linder, W. H. Dennen

The graphitic carbon content of soils may be used to detect and delimit subsurface graphitic zones. Spectrographic measurement of carbon in C horizon soils from several areas in the northeastern United States shows good correlation with known graphitic bodies. Bodies of graphite and sulfides are readily located by electromagnetic prospecting methods, but these methods cannot generally discriminate between them. Usual practice, therefore, requires follow-up work on electrically anomalous areas by trenching, drilling, or soil sampling in order to determine the mineralogical nature of the conductor. The efficiency and cost of such follow-up is consequently an important factor in prospecting. The presence of buried sulfide deposits is often reflected in concentrations of metals in the superincumbent soil. Simple chemical tests for such metal concentrations have been developed and applied with considerable success. Bodies of graphite or mixtures of graphite and sulfides are, however, very common and a means whereby buried graphite could be detected by soil testing should provide valuable additional information in the search for ore sulfide and graphite deposits. Graphite is a notably stable substance and should persist in soil above graphite-rich horizons. Microscopic examination of soil samples high in carbon, however, failed to reveal any recognizable graphite fragments indicating a grain size in the clay range. Presumably such small particles would have some mobility in a soil by a translocation mechanism similar to that proposed for the movement of clay particles in a soil profile. Experimental data supports this idea since the boundary between background and anomalous soils carbon values is quite sharp, but the anomalous zone is slightly broader than the graphitic source rock. A simple spectrochemical technique for the determination of carbon in geological materials has been described by Dennen,1 and may be directly applied to soils. A modification of this technique which employs an arcing chamber through which nitrogen is passed is recommended to decrease contributions from atmospheric carbon dioxide. Tests indicate that soils over graphitic zones may be strongly enriched in carbon. The spectrochemical determination of carbon depends upon the formation of the cyanogen molecule (CN) from carbon in a sample and atmospheric nitrogen, under the high temperatures associated with a dc arc. Samples for analysis are dried, lumps broken, and screened. A small portion of the -100 mesh fraction is packed into a copper electrode and excited as the cathode of a dc arc. The band spectra of cyanogen are recorded photographically and the density of the bandhead CN 3883A is measured. The limit of detection of the method is about 0.01 pct C and its coefficient of variation is about 15 pct. Soils, of course, contain carbon in other forms than graphite, and the amount of interference from such sources was examined. The C horizon of several soils from Massachusetts, Maine, and Pennsylvania were found to have a carbon content of 0.3 to 0.5 pct by weight. This content is chiefly due to the presence of carbonates and vegetable matter in the sample and may be readily eliminated, or at least

Jan 1, 1961

By A. M. Keenan, R. H. Carpenter

Geologic faults have always been a plague to the mining industry, and have often reduced a mining venture from a profitable to a marginal operation, and even at times have forced companies to liquidation or bankruptcy. The use of geology as an economic tool in coal mining is not generally recognized, particularly in coal deposits which are horizontal or essentially flat-lying, in which faulting might not be prevalent. However in pitching coal seams, the existence of faults is considered an inherent challenge, as the inclination of the seam or seams per se, is a product of geologic disturbance. The problems of faults are a constant challenge to the management of the Thompson Creek Coal and Coke Corp. in their operations in Pitkin County, Colorado, where high grade medium volatile coking coal is mined. The background for this paper has been provided by the experiences of these operations, in overcoming the effects of faults in mining, and resolving the fault structures. The properties of the Thompson Creek Coal and Coke Corp. are located in central Colorado, 13 miles southwest of Carbondale, Colorado, a tow] on the main highway between Glenwood Springs and Aspen, Fig. 1. The elevation at the mine portals is approximately 8000 feet: there is a relief of some 2.000 feet to the adjacent ridges rising away from the [nine portals. 'The entire present production of these properties totaling 180.000 tons of clean coal per year is trucked to the railhead at Carbondale, Colorado, from whence it is shipped to the Geneva Steel Plant at Provo, Utah. The properties were initially opened in September 1952. A total of 125 men are currently employed with the production conting from the Number 1 and 3 Mines, and development workings of the Number 2 and 5 Mines respectively. While the No. 2 Vine was opened in 1953 prior to No, 3 Mine, the encountering of faults without sufficient development work accomplished to sustain production, necessitated the diversion of manpower to the other [nines for economic considerations. GEOLOGY '1-he productive coal seams occur in the Mesaverde formation of Late Cretaceous age which outcrop along the eastern edge of the Piance Creek Basin from the Grand Hogback, a part of the southwestern flank of the White River Uplift north of Glenwood Springs, southward through the 'Thompson Creek area and the

Jan 1, 1961

By Eugene R. Rice

There are many methods for determining the meridian, but all of those in common use involve at least two separate observations, one for latitude and one for azimuth. Such observations made upon a south star at any hour are open to the objection of possible inaccuracy due to ignorance of the absolute refraction, and also to slow change in the altitude of the star when near the meridian. The method of observing a circum-polar star at elongation. besides requiring a separate observation for latitude, is open to the serious objection that clouds may obscure the star at the critical moment. Moreover, a tedious wait for the star to come to elongation is sometimes necessary. Many of us can recall 'long, cold, weary vigils, waiting for Polaris to reach elongation. For observing a circumpolar star at any hour, not only the latitude, but also the true time, must be known. This it is practically impossible to obtain, except in regions reached by the telegraph, and usually then one has to know the longitude also, in order to reduce " standard time" to " local time." The results obtained by this method, when the star is at culmination, are not very good, unless the true local time is absolutely known. The methods of obtaining the nleridian from the sun, by means of a solar attachment, or by direct observation, while good, are not absolute, by reason of refraction, change in declination of the sun, and small change in vertical angle, when the sun is near the meridian. For these two methods, latitude, time, and approximate longitude have to be known. In the method here described, only one observation is needed, and from it are computed azimuth, latitude, aud sidereal time. In other words, one call observe a circumpolar star—Polaris

Jan 1, 1911

By Basil B. Zavoico

CRUDE oil production in the United States during 1938 reached approximately 1,214,355,000 barrels, an average of 3,327,000 barrels per day, or 5 per cent below the 1937 record output of 1,279,160,000 barrels. The decreased production did not prevent the stocks of all products from increasing to a total of 575,954,000 barrels by Sept. 30, an increase of 10,957,000 above the total on Jan. 1, or an average daily storage increase in all products of 40,135 barrels. The increase in total stocks was made entirely in the refined products, stocks of crude oil during the first nine months of 1938 having actually declined 7,155,000 barrels to 299,671,000 barrels, or an average daily decline of 26,209 barrels. The 1937 reversal of the preceding five-year trend of discoveries totalling less than withdrawals was continued through 1938 with indicated reserve addition from both new discoveries and extensions considerably in excess of the

Jan 1, 1939

By Philip B. Bucky

CONTENTS [PACEPACE r. What Is a Rock Burst?2 4. How Can Rock Bursts Be Predicted? . 35 Jack Spalding2Jack Spalding35 A. F. Robertson 2, 5A. F. Robertson35 W. R. Crane 2A. B. Yates and P. J. Shenon. . . . 35 G. S. Rice 2W. R. Crane 35 P. J. Shenon 2G. S. Rice 35 L. C. Graton 2B. F. Tillson 36 2. What Are the Causes of Rock Bursts? 6 5. How Can Rock Bursts Be Controlled?. 36 Jack Spalding6Jack Spalding36 A. B. Yates and P. J. Shenon . 7, 12, 29A. F. Robertson 36 A. F. Robertson 12, 28W. R. Crane37 W. R. Crane 15A. B. Yates and P. J. Shenon. . . . 37 G. S. Rice 15Oscar Weiss38 Oscar Weiss15G. S. Rice37, 42 P. B. Bucky21R. D. Hoffman42, 43 P. H. Bird 21, 26, 28R. D. Hall 42 M. K. Hubbert26R. H. Cromwell42 G. Wheeler 26. J. Shenon 42 B. F. Tillson26, 28P. B. Bucky42, 44 T. T. Read 27B. F. Tillson 42, 44 A. B. Yates 43, 44 3. How Can Rock Bursts Be Prevented? . 30P. H. Bird 43 Jack Spalding. . . . • . • • • • . 306. General Discussion . A. B. Yates and P. J. Shenon. . . . 31Jack Spalding44 A. F. Robertson32R. D. Parker49 W. R. Crane 35C. Baring Horwood 51 G. S. Rice 35P. B. Bucky 52] FOREWORD THIS symposium brings together points of view, experiences and ideas on rock bursts from a goodly portion of the globe. Some conceptions, particularly those regarding the necessity of depth, have been fairly well shattered, as we find that they are present in the water tunnels of New York, on the surface at marble quarries in Vermont, and in the coal mines of the United States, as well as in the deep mines of the South African and Kolar gold fields, and in the nickel, copper and gold mines of Canada. Their occurrence under such a variety of conditions is, therefore, a challenge,

Jan 1, 1942

By R. F. Shurtz

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

Jan 1, 1967

By Edwin Berry

THE consideration of the present value of a mine is of great importance when planning for the operation of a property,, and it is particularly so in the case of mines that have large ore reserves. At various times during the past 15 years, the writer has had occasion to make rather thorough studies of the subject, and has been greatly impressed by certain important points which these studies have brought out, points which, though they may be well known, are often lost track of in the rush to obtain low mining costs and high daily tonnage output. . It is the object of this paper to present briefly, and in a general way, some of these points, and especially those which have to do with the relationship which (1) ore reserves and plant capacity, (2) grade of ore mined, and (3) ore losses in mining, bear to the present value. Present value, sometimes called present worth or actuarial value, means the value today of the future earnings of an enterprise. Great industrial, manu-facturing or railroad enterprises, if properly handled, go on indefinitely and their value is directly dependent on their estimated annual earnings. Mines, or oil properties, on the other hand, have an earning capacity only until the ore or oil is exhausted, and their present value is dependent not only on their annual earnings but also on their life, which is the length of the period over which they can produce at a profit. A mine, or an oil property, is a "wasting asset," while an estab-lished manufacturing business is not, or should not be. In other words, the present value of a mining property. represents a sum of money on which there could be paid from operating profits a determined rate of interest, say 8 per cent., and in addition an amount which, if invested at compound interest as received, would at the end of the life of the mine pay back the present value. In his "Wealth and Income of the American People," Walter Renton Ingalls says: "The fundamental principle of mine valuation is the present worth of an annual dividend accruing during the period of years corresponding to the life of the mine."

Jan 7, 1922