Search Documents

E. B. WILSON, Scranton, Pa. (written 'discussion *).-Prof. Young's paper shows another application of electricity in solving problems in coal mining, and suggests that it may be possible to utilize the data he has collected in developing an electric firedamp detector. If electric lamps are to be adopted in gassy coal mines, the use of an electric firedamp detector becomes almost imperative, for safety lamps and electric lamps in the same mine are not always conducive to safety, and Liveings electric firedamp detector, is too cumbersome to meet with general approval. Three well understood facts are verified in a new way by Prof. Young's experiments: - 1. The temperature at which methane ignites. 2. The more inflammable gas present in an atmosphere, the hotter will be the flame, and the longer the cap in a safety lamp. 3. As the temperature at the source of ignition varies, the length of the gas-cap flame varies. Prof. H. B. Dixon collaborating with Mr. H. F. Coward, some years ago, made experiments on the ignition of various gases to find the tem-perature of their kindling points.1 From the results of their experiments, the writer has culled the ignition temperatures of some hydrocarbon gases, and has tabulated them with other data, in Table 1.

Jan 10, 1919

By D. S. Campbell

THE chief factors influencing the decision to build the Big Missouri mill underground were the topography of the country and the climate. The location underground assured certain saving in the cost of operation, such as the hearing of the mill, shovelling snow, and handling ore, which, over a period of time, would offset the greater initial cost of the mill excavation and machinery installation underground, as compared with the cost of a like plant on the surface. At Gilman, Colorado, where conditions are somewhat similar, the Empire Zinc Company, at their Eagle mine, are treating their lead-zinc ore in a mill built entirely underground. Company officials made a study of this plant before proceeding with the mill at Big Missouri. LOCATION, CLIMATE, TOPOGRAPHY The Big Missouri mine is situated on the Upper Salmon river, 22 miles north of Stewart, B.C., which is at the head of Portland canal, a narrow natural channel which penetrates 100 miles inland from the coast into the Coast Range mountains. Stewart, the distributing centre for the district, is about 600 miles north of Vancouver. The Big Missouri claims lie on and down the sides of the Big Missouri ridge, which extends north and south between the Salmon River and Cascade Creek valleys. The ridge rises to an elevation of 3,600 feet, is about half a mile wide, and to the east slopes down to the Joker flats in Cascade Creek valley. The Big Missouri camp is located on the flats at elevation 2,800 (see Figure 1). Preliminary development of the property took place from this point with an adit driven under the ridge. The western side of the ridge slopes steeply down to the Salmon glacier at elevation 1,900. Ore found on the 2,850 level extended down, and, in order further to explore the ore-body, the 2,850 level was driven through to the west side of the ridge, a surface incline tramway was built, and a lower tunnel driven at elevation 2,350, five hundred feet below the original 2,850 level, from the west side of the ridge. This tunnel development avoided the necessity of sinking, which would have been costly, as the mine makes a great deal of water (see Figures 1 and 2).

Jan 1, 1938

Jan 1, 1968

By B. M. Larsen, K. Heindlhofer

THIS paper describes a relatively simple electrical apparatus that, through the close analogy between the flow of heat and of electricity, enables one to solve quickly and with satisfactory accuracy many complex problems in heat flow. This device, developed in 1935, has proved especially useful in the solution of certain practical problems relating to the design and efficiency of regenerators for an open-hearth furnace or coke oven, yielding within a few hours information that would take weeks or even months to acquire by mathematical1.2 or experimental3 methods of comparable accuracy. Its description now is prompted by growing interest in such analogues, as shown by several recent papers.4.5 The analogy between flow of heat and of electricity appears to have been recognized first by Maxwell who, in his famous Treatise on Electricity and Magnetism (1881) says: The analogy between the theory of the conduction of electricity and that of the conduction of heat is at first sight almost complete. If we can take two systems geometrically similar, and such that the conductivity. for heat at any part of the first is proportional to the conductivity for electricity at-the corresponding part of the second, and if we also make the temperature of any part of the first proportional to the electric potential at the corresponding point of the second, then the flow of heat across any area of the first will be proportional to the flow of electricity across the corresponding area of the second. .. Thus, in the illustration we have given, in which flow of electricity corresponds to flow of heat, the electric potential to temperature, electricity tends to flow from places of high to places of low potential, exactly as heat tends to flow from places of high to places of low. temperature He noted, however, that this analogy is restricted: ... there is, however, one remarkable difference between the phenomena of electricity and those of heat. Suspend a conducting body within a closed conducting vessel by a silk thread, and charge the vessel with electricity. The potential of the vessel and of all within it will be instantly raised, but however long and however powerfully the vessel be electrified, and whether the body within be allowed to come in contact with the vessel, or not, no signs of electrification will appear within the vessel, nor will the body within show any electrical effect when taken out. But if the vessel is raised to a high temperature, the body within will rise to the same temperature, but only after a considerable time, and if it is then taken out it will be found hot, and will remain so till it has continued to emit heat for some time. The difference between the phenomena consists in the fact that bodies are capable of absorbing and emitting heat, whereas they have no corresponding property with respect to electricity. According to this statement the application of the analogy would be limited to problems of steady flow that do not involve heat-capacity effects. In spite of this

Jan 1, 1945

By William J. Campbell

Expansion measurements of platinum, added as an internal standard, are used for thermal calibration of X-ray cameras and diffractometers. Accuracy of the temperatures derived by this technique depends on the precision of expansion measurements and the reliability of reference expansion data. Temperature measurements to ± 1° C. require ?d or ?a to be determined within ± 0.001 percent. Selected expansion data are concluded to be reliable to 2° C., 5° C., and 25° C., over the temperature ranges 0° C. to 700° C., 700° C. to 1,000° C., and 1,000° C. to 1,700° C., respectively. Tabular expansion values from 25° C. to 1,700° C. in 2° C. intervals were calculated from the following equation; Expansion, percent = [8.91 + 1.28 x 10-3(t-25) + 0.04 x 10-6(t-25) ] [t-25.104 ] These tabular values facilitate future corrections of published temperatures as more reliable expansion-temperature data become available.

Jan 1, 1962

By D Craw, K A. Hunter

Deposits of the metalloids arsenic and antimony occur in quartz veins of mesothermal hydrothermalsystems in the South Island as arsenopyrite (AsFeS) and stibnite (Sb2S3). Arsenopyrite and stibnite occur in natural exposures in gold-mining areas, and additional arsenopyrite and stibnite have been exposed to the atmosphere by mining activity. At present the drinking water limits for dissolved As and Sb are 10 ppb and 3 ppb respectively. Sampling and analysis techniques are critical to determination of metalloid concentrations at these low levels. Endeavour Inlet in the Marlborough Sounds is an historic mining area (late 19th Century) with elevated As and Sb in waters emanating from mineralised rocks. Waters running out of abandoned adits have concentrations of As and/or Sb up to ppm levels. Natural waters have high Sb and low As, and the As levels increase markedly where anthropogenic activity has exposed rock. Changes in Sb/As ratio could potentially be used to quantify the anthropogenic component of metalloid mobility on mine sites on the 100-year time scale.

Jan 1, 2002

By W. R. Bull

This paper examines water-only cyclone performance for the cleaning of fine coal, and the effects of changes in feed flow rate, feed pulp density, and vortex finder diameter. A model is presented for performance simulation which can be used to predict products obtained based on feed washability data.

Jan 1, 1987

The gold concentration profiles which develop inside the activated carbon particles during the adsorption process were measured, so as to obtain additional direct proof of intra-particle mass transfer rate-control and to determine how individual carbon particles in a population vary in their gold uptake behaviour. The observed gold concentration profiles inside the activated carbon particles were typical of situations where an intra-particle mass transfer mechanism is rate-controlling. Gold di-cyanide penetrated the carbon particles with a wave-like front until it was uniformly distributed throughout the particle. This corresponds with the profiles predicted by the film and surface diffusion model. However, the rate with which gold di-cyanide was transported inside the individual carbon particles varied within the population of carbon particles. This variation was characterized by a lognormal distribution in surface diffusivity. Because the estimated variances of these surface diffusivity distributions were small, the dynamic adsorption behaviour of the carbons used in the present study did not deviate significantly from that predicted by a model based on film mass transfer and a single surface diffusivity. Van Deventer (1984, 1985 and 1986a) reported data that could not be adequately described by a model based on film mass transfer and a single surface diffusivity. In this study a model based on film mass transfer and a wide lognormal distribution of surface diffusivity values was applied to his data. It was shown that a population of carbon particles with a wide distribution in surface diffusivity values could offer an alternative explanation to the mechanism proposed by Van Deventer which was based on film mass transfer, with partitioning of the carbon into micro- and macropores with surface diffusion in the macropores and slow mass transfer into the micropores.

Jan 1, 1997

By C. B. Manula, R. L. Sanford, R. A. Rivell

PART I. FLOW CHARTS

Jan 1, 1974

This paper describes the circuit simulations based on SPICE of the SDI Electronic Detonator System at the system level. SDI is launching the Electronic Detonator System with a robust serial protocol exhibiting great ease in field usability and deployment. Programmable delay time with increment of 1 ms up to 10s is possible. Bus length of up to 2 km containing 1600 detonators can be utilized. This system was analyzed using SPICE simulations and an Excel-based firing model spreadsheet. The effects of wire diameter, resistivity, detonator leakage characteristics, blasting array topology (lumped, linearly distributed or branched) were simulated using the firing model. Such spreadsheet is instrumental in determining the blasting topology of any given detonator number and bus wire diameter or resistivity. Initial simulation results were interactively coupled back into making the serial protocol more robust during typical mining conditions.

Jan 1, 2006

By W. R. Reed, G. J. Joy, B. Kendall, A. Bailey

"Testing of the roof bolter canopy air curtain (CAC) designed by the U.S. National Institute for Occupational Safety and Health (NIOSH) has gone through many iterations, demonstrating successful dust control performance under controlled laboratory conditions. J.H. Fletcher & Co., an original equipment manufacturer of mining equipment, further developed the concept by incorporating it into the design of its roof bolting machines. In the present work, laboratory testing was conducted, showing dust control efficiencies ranging from 17.2 to 24.5 percent. Subsequent computational fluid dynamics (CFD) analysis revealed limitations in the design, and a potential improvement was analyzed and recommended. As a result, a new CAC design is being developed, incorporating the results of the testing and CFD analysis.IntroductionExposure to respirable coal mine dust can cause coal workers’ pneumo-coniosis (CWP), also known as black lung. If silica is present in the dust, the miner may develop silicosis in addition to CWP. CWP and silicosis are occupational respiratory diseases that are ultimately fatal and have no cure. The only method of prevention is to eliminate exposure to respirable coal mine dust and crystalline silica, or quartz. The occupational exposure limit on a Mining Research Establishment (MRE) basis for respirable coal mine dust had been 2 mg/m3 during each shift that a miner is exposed in the active workings of the mine or in mine facilities. Under recently enacted legislation, this standard was changed in August 2016 to 1.5 mg/m3 for a full working shift (The Office of the Federal Register, 30 CFR 70.100, 2015). When respirable quartz is present, the mine must maintain its average concentration at or below 0.1 mg/m3. If the mine exceeds the 0.1 mg/m3 respirable quartz dust concentration, then the applicable respirable dust standard is reduced, calculated as 10 divided by the percentage of quartz present (The Office of the Federal Register, 30 CFR 70.101, 2015).The sources of exposure to respirable coal mine dust for roof bolting occupations include infrequent maintenance and cleaning of the vacuum dust collection system and operating the bolter downwind — in the return air — of the continuous miner (Good-man and Organiscak, 2003). Recent studies have demonstrated that vacu-um dust collection systems are effective in capturing bolter-generated dust if maintained and operated correctly and if proper face ventilation techniques are used. However, most expo-sure to respirable coal mine dust for a roof bolter occurs when the roof bolter machine is operated downwind of the continuous miner (Potts, Reed and Colinet, 2011; Colinet, Reed and Potts, 2013). Because of this higher exposure downwind of the continuous miner, the roof bolter is often limited to working downwind of the miner only once during a production shift."

Jan 1, 2017

By K. A. Gschneidner, O. D. McMasters, T. J. O’Keefe

X-ray diffraction, differential thermal, ad rnetallo-graphic methods were used to establish the Dy-Pb Phase diagram. Lead additions lower the 1377°C transformation temperature of dysprosium to 1360°C leading to an inverted peritectic reaction. The 327°C melting point of lead is lowered by dysprosium additions to about 326°C yielding a eutectic reaction. A second eutectic reaction occurs at 13.3 at. pct Pb and 1200°C. The dysprosium-richest intermetallic compound DysPb3 melts congruently at 1695°C and crystallizes in the hexagonal Mn5Si3 (D8,) type structure. The peritectic decomposition temperatures for the remaining compounds are Dy5Pb, at 1555C, DyPb2 at 955C, and DyPb3 at 880°C. A fifth compound near the DyPb stoichiometry exists over a 310°C temperature range decomposing at 1130°C by means of an inverted peritectic reaction and melting incongruently at 1440°C. The crystal structures of the compounds are discussed. A systematic study of the rare earth-lead alloy systems is underway in an effort to supply information concerning the alloying behavior of the rare earth metals. The Dy-Pb phase diagram is the fourth system to be investigated in this study. The Yb-Pb,1 Y-Pb,2 and Eu-Pb 3 diagrams have been published recently. Utilization of the rare earth series of metals as a research tool in this manner should yield a better understanding of alloy formation. EXPERIMENTAL PROCEDURE Materials. The lead used in this investigation was obtained from Cominco Products, Inc., and was specified to be 99.99 pct pure. The dysprosium was prepared in this Laboratory by the calcium reduction of the fluoride followed by distillation of the dysprosium. The major impurities in the dysprosium in ppm are: A1 (<40), Ca (400), Er (<50), Gd (<200), Ho (<200), Mg (<50), Si (30), Ta (400), Tb (<100), Y (<50), 0 (651, H (15), N (not detected), F (430), C (35). Alloy Preparation. Most of the alloys were prepared by melting weighed amounts of dysprosium and lead in sealed tantalum crucibles. The tantalum crucibles were sealed by are-welding in a He-Ar atmosphere welding chamber. Thus the alloys are in contact with He-Ar at about 1 atm pressure. Homogenization was achieved by holding them in the liquid state for about 1 hr, cooling, inverting the crucibles, remelting, and repeating the process at least twice. Since these alloys were prepared in sealed tantalum crucibles, chemical analysis for final composition was thought to be unnecessary. No detectable reaction of these alloys with the tantalum crucible was observed by metallographic examination. Metallographic evidence was also used to confirm the homogeneity of some of the alloys prepared in this manner. The compositions of a few alloys, which were prepared by nonconsum-able are-melting, were corrected for the small weight losses involved by assuming that the weight loss is due to vaporization of lead. The specimens obtained from the alloy samples were prepared under a dry-argon atmosphere because they were rapidly attacked by air and moisture. Thermal Analysis. Differential thermal analysis methods were used to determine the liquidus curves and reaction horizontals of the system. Both Pt vs Pt + 13 pct Rh and W + 5 pct Re vs W + 26 pct Re thermocouples were used to measure the temperature. An X- Y recorder was used to record the specimen temperature and differential electromotive force between the specimen and molybdenum standard. The arrest temperatures were measured potentiometri-cally. The accuracy limits (* values) associated with the reaction temperatures obtained by this method were estimated on the basis of both the reproducibility of the particular temperature value and the accuracy of the thermocouple at a given temperature. Liquidus temperatures were obtained from cooling arrest data while both heating and cooling arrest data were used to establish the horizontals of the diagram. Heat treatments during the thermal analyses of the alloys between 40 and 70 at. pct Pb were necessary in order to approach equilibrium conditions. The samples were held at temperatures between the various peritectic horizontals for l to 2 hr before the thermal analyses were continued. The entire range of compositions was investigated at the expense of a minimum amount of materials by adding appropriate amounts of lead to master alloys. More than sixty alloys were analyzed by this differential thermal method and for each alloy the results given herein are taken from two or three heating and cooling cycles. X-Ray and Metallographic Methods. Slice specimens for metallography and powder specimens for X-ray diffraction were prepared from rod-shaped samples which had been melted in sealed 0.62 5-cm-diam tantalum crucibles. The specimens were heat-treated in sealed tantalum crucibles which were protected by sealing them in argon-filled quartz ampules. Quenching was accomplished by breaking the ampules in ice water after heat treatment. X-ray powder specimens were sealed in 0.3-mm-diam glass capillaries under a dry-argon atmosphere. Copper, iron, and chromium radiation were used to obtain the powder patterns for these alloys. More than 150 powder patterns were obtained for specimens of various compositions and heat treatments. Included in these were several patterns for specimens which had purposely been oxidized. Patterns from specimens which had been accidentally exposed

Jan 1, 1969

By Juan Ayza

La permanente exposición y concentración de polvo en la zona minera, han sido materia de múltiples enfermedades mortales para el personal que labora en ella. Tal ese así que el polvo de sílice libre es la causa fundamental de la alteración pulmonar llamada silicosis. Por tal motivo, el objetivo del trabajo revisa las propiedades de los polvos, los medios para detectarlos, indemnizaciones y los sistemas eliminadores de los mismos. En cuanto al sistema de producción, el polvo se extiende a través de laventilación, humedad, cargas eléctricas, entre otros, influenciando en el muestreo cuantitativo y en la creación de un método cualitativo de estudio, para complementarlo.Asimismo, se determina que el desarrollo de la silicosis se relaciona en el cuarzo como causa principal de dicha anomalía, aumentando el peligro de infección y la capacidad pulmonar. Para contrarrestar dicha enfermedad se busca soluciones alternativas como el uso del agua, aceita, una ventilación adecuada, los buenos hábitos en el trabajo, la floculación, el método porofliáctico de aluminio, concluyendo que el Hematocímetro es el más exacto y práctico de los anteriormente usados, dado su costo como su requerimento de instrumental menos complicado.

Jul 20, 1955

MR. W. E. WAINWRIGHT occupied the chair, and in introducing the lecturer said, on account of the absence of the vice-president, it fell to his lot to introduce the lecturer. Mr. Tennberg, he said, was visiting Australia, and those present might wonder who he was.He understood that the lecturer w~s a reputable practising geophysicist, associated with a reputable company! It was rather desirable perhaps to say that the Institute had made some inquiries with regard to his status. Geophysics was a comparatively newscience, and had suffered several hard knocks in Australia and elsewhere. Most of those knocks had been the result of undue optimism of a number of people who did not understand what they were talking about. It had been claimed that geophysics was a...

Jan 1, 1930

By D. C. Torre

The need for a successful, efficient and reliable continuous face- haulage .system for use with continuous mining machines has been apparent since the first continuous miners were introduced some twenty-five years ago. Some thought and effort were given to the development of continuous haulage over the last twenty years or so. Some initial success was experienced in this area by The Long Company with a system involving bridge conveyors, as far back as the late 1950&apos;s. However, extensive success with continuous face haulage for use behind modern, high product¬ion, continuous miners escaped the industry until the early 1970&apos;s. It is true that continuous face haulage was successfully introduced into low seam mining, generally in seams ranging under 1.07 m (42") in height, in the 1960&apos;s, for use with relatively low production, low seam, auger type continuous miners. However, those available systems which have achieved success in the lower seams, where relatively low capacities are adequate, are not directly applicable for use with today&apos;s medium and high seam miners with their standard production capacity of 9.1 - 10.9 mtpm (10 - 12 tpm). Since the late 1960&apos;s and early 1970&apos;s, several machinery manufacturers, and at least two major coal companies, have devoted considerable expense, time and effort to developing truly successful continuous face haulage for use in coal seams ranging upward from 1.2 m (4&apos;) in height. Continuous face haulage equipment has been developed in the last five years employing a variety of transportation media and design concepts, including some which have received wide publicity such as those employing hydraulics, and pleated belt. The truth of the matter is, however, that the only universally applicable and widely successful continuous face haulage equipment introduced to date has been that employing a combination of bridge conveyors and mobile, self-propelled, bridge carriers, connected at the inby end to the tail of the high production continuous miner, and at the outby end attached directly to the panel conveyor (Fig. 1 & Fig. 2) or, on occasion, to a short, self-contained conveyor which, in turn, empties directly onto the panel conveyor. While these bridge type continuous haulage systems are available with both belt and chain conveyor components, the most widely applied and successful system in seams above 1.07 m (42") in height is that offered by The Long-Airdox Company. The standard unit for use with 9.1 - 10.9 mtpm (10 - 12 tpm) continuous miners is normally equipped with belt. However, they have built, and successfully applied, versions of this system employing chain conveyors, (Fig. 3), mainly for operators having extremely difficult mining conditions, including excessive amounts of water

Jan 1, 1977

By Thomas E. Shufflebarger

Glass sand is a virtually pure, fine- to medium-grained, quartz sand. It is produced in 25 states from a variety of chemically different source rocks. Deriving their raw material largely from either friable sandstones or loosely consolidated sands, 59 operations produced 14.9 million tons of melting sand in 1976. About one-third of this tonnage was obtained from the Oriskany and St. Peter Sandstones. Glass-sand prospects are discussed in this paper with regard to chemistry, environment, transportation, and costs. Demand for a quality product will range from 36 million to 46 million short tons in 1995.

Jan 1, 1978

By Chris Mark

Successful longwall mining requires a stable tailgate entry. Gate entry performance is influenced by a number of geotechnical and design factors, including: - Pillar size and pillar loading; - Roof quality; - Floor quality; - Entry width; and, - Artificial support (primary and secondary). This paper describes a comprehensive, practical, design methodology, based on statistical analysis of a nationwide data base of longwall ground control experience. Geotechnical surveys were conducted at 44 U.S. longwall mines, and underground observations of site geology, entry conditions, and support design were recorded at each mine. The observations were combined with discussions with mine personnel to identify 69 longwall gate entry designs as satisfactory, unsatisfactory, or borderline. Only conventional longwall designs, in which the pillars are expected to carry the full abutment loads, were included in the data base. Designs which employed yield pillars only were excluded. The case histories were characterized using five descriptive parameters. Pillar design was described by the Analysis of Longwall Pillar Stability Factor (ALPS SF). A major new contribution is the Coal Mine Roof Rating (CMRR), a rock mass classification system that quantifies the structural competence of bolted mine roof. Other quantitative measures were developed for primary support, secondary support, and entry width. Multivariate statistical analyses indicated that in 84% of the case histories the tailgate performance could be correctly predicted using just ALPS and the CMRR. Most of the misclassified cases fell within a very narrow borderline region. The analyses also confirmed that primary support and gate entry width are essential elements in successful gate entry design. The relative importance of the floor and of secondary support could not be determined from the data. Based on these results, a simple equation was developed to guide the design of longwall pillars and gate entries: ALPS SF,, = 1.76 - 0.014 CMRR Where: ALPS SF, = ALPS SF suggested for design. Guidelines for entry width and primary support density, as related to the CMRR, are also provided.

Jan 1, 1993

Mr. Address Member is hereby proposed by the undersigned, as a Associate Junior Member of the American Institute of Mining Engineers. Signatures of three Members or Associates. Place of birth Year of-birth Education, when, where and how acquired, with degrees, if any. A technical education is not requisite for membership. Dates Please give record of experience on following page with dates; for e. ample, in the form used by "Who&apos;s Who In America" and similar publications.

Jan 6, 1917

By Maurice Deul

Certain health and safety hazards occur entirely unexpectedly in some subterranean excavations. Although ground support is not the subject of this paper, ground failure can result in large and often uncontrolled flow of fluids into an excavation. Even when there is no ground failure, the disturbance of nature&apos;s equilibrium between rock or unconsolidated alluvium or rubble and the contained fluids poses severe problems to a well planned operation. Optimum conditions for safe operation cannot be the sole criterion for site selection. Some mineral deposits form in zones of structural weakness, others form where hydrothermal alteration substantially weakens the enclosing rock, and tabular deposits such as coal and evaporites inevitably undermine large areas. Excavation to acquire mineral values cannot be relocated. The same is often true for tunnels driven to connect distant points by the most direct route. Rivers and mountains cannot he avoided, and the cost of lengthening a tunnel--by even a fraction of a percent--must be strongly justified. No responsible engineer will knowingly select a dangerous route for excavation, but to what extent do engineers attempt to assess the health and safety hazards that may be reasonably expected? How, specifically, can methane explosions, water and sand flooding, dangerous dusts, toxic gases, thermal shock and radar poisoning be eliminated or minimized through systematic advance planning?

Jan 1, 1974

THE Institute assembled in the Hall of the Boston Natural History Society on Tuesday evening. Dr. T. Sterry Hunt, of the Boston Institute of Technology, after a brief address of welcome to the Institute, read an introductory paper on the Geognostical History of the Metals. President Raymond responded to the welcome of Dr. Hunt. The following names were then presented to the Institute, with the recommendation of the Council, for election: Adams, J. M., . . . . . . Silver City, Idaho. Daggett, Ellsworth,. . . . . Salt Lake City, Utah. Geist, Alfred W., . . . . . Boston, Mass. Hays, Dr. S. Dana, . . . . . Boston, Mass. Heinrich, Oswald J., . . . . Midlothian, Va. Johnson, J., . . . . . . Braidwood, Ill. Leckie, Robert G., . . . . . Actonvale, Canada. Lyman, Edward, . . . . &apos; . Troy, N. Y. Maltby, William, . . . . . Braidwood, Ill. Nichols, Lyman, Jr., . . . . Bbton, Mass. Ordway, Prof. J. M., . . . . Boston, Muss. Rand, Theodore D , . . . . . Philadelphia, Pa. Richards, Prof. Robert H., . . . Boston, Mass. Roclrwell, Prof. Alfred P., . . . Boston, Mass. Roepper, Charles W ., . . . . Bethlehem, Pa. Schulz, A. von, . . . . . Central City, Colorado. Singer, William F., . . . . Pittsburgh, Pa. Spillsbury, E. G., . . . . . New York. Wells, Calvin, . . . . . . Pittsburgh, Pa. The session concluded with the reading and discussion of a paper, by Henry Engelmann, On the Mines and Ores of the Little Cottonwood Canyon, Utah. The second session was held on Wednesday morning, when the following papers were presented : On the Midlothian Coal Mines, by Oswald J. Heinrich. On the Probable Existence of Microscopic Diamonds in California, by Prof. Benjamin Silliman.