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Albin, B. R. Billings, Mont. 28 Amster, Nathan L 25 Broad St., New York, N. Y. '28 Bache, Jules S. 42 Broadway, New York, N. Y. 28 Barrett, C. P. 5338 Harper Ave., Chicago, 111. '28 Baum, Frank G., Cons. Hydro-Electric Engr Cassel, Shasta Co., Cal. '28 Bayless, William S. Russ Bldg., San Francisco, Cal. '28 Bean, Louis H.60 E. 42nd St., New York, N. Y. '28 Beatty, Roes J. 1105 First National Bank Bldg., Chicago, Ill. '28 Benwell, Oswald F. Hold Mags. '28 Beymer, Albert S., V.P., Keystone National Bank Pittsburgh, Pa. '28 Blumenthal, Hugo 44 Pine St., New York, N. Y. '28 Boettcher, Charles Ideal Cement Bldg., Denver, Colo. '28 Bowlus, Thomas H. Iola, Kan. '28 Brown, Colvin B. Chamber of Commerce, Washington, D. C. '28 Bart, Maxwell Struthers Southern Pines, N. C. '28

Jan 1, 1932

By James Marsh

INTRODUCTION Economists have long expressed suspicion of the economic theory of natural resource exhaustion, even in writing articles which have contributed to it (1). Indeed, the gap which separates the pure theory from practical management seems unusually wide. It is doubtful whether a mine manager could possibly know enough about the relevant parameters of his mine to steer it along the optimal paths described by the theorists (2). Nevertheless, enough faith in the theory remains that mine managers are suspected of being a separate breed whose behavior must be studied in special courses using specialized text-books, collections of readings, and journals (3). The implied hypothesis, that mines and natural resource firms are managed differently than other firms, is the subject of this paper. In the next section the theory is developed and analyzed. In section III, I discuss the implications of the statistical results that have been obtained. Finally, conclusions are reserved for section IV. THE MODEL A key difference between the traditional theory of natural resource production and that of other forms lies in the set of variables which ire assumed to jointly determine the quantity of output the firm will produce. Output, in the non-resource case, is assumed to be a function of k clearly definable and distinguishable inputs or factors of production, viz., y = f(xl, x2, ..., xk), (1) here

Jan 1, 1977

By Benjamin Moore

AT present the demands of the United States for strontium are met by imports from Germany, England and Canada, which vary considerably in proportions of ore and finished salts, in tonnage and in value. Statistics for the period 1926-1932 are given in Table 1. Domestic deposits are TABLE 1.-Strontium Imported into the United States, 1926-1932° Ore Chemicals Year Short Tons Value Pounds Value 1926 2,200 $58,159 5,433,044 $115,436 1927 1,356 58,711 4,233,816 149,383 1928 759 31,157 3,380,464 136,561 1929 973 45,505 4,578,327 196,233 1930 220 10,459 2,153,788 104,807 1931 (260 lbs.) 123 1,742,714 83,564 1932 5 276 469,481 20,910 a Mineral Industry (1934) 42, 61. known in many states, but the larger and purer ones are in the West, particularly in the desert region of southeastern California and western Arizona. These deposits are large enough to command interest, par-ticularly in consideration of future cheap power at the Boulder Dam. The deposits described in this paper were examined during an investi¬gation of the, mineral resources of the Boulder Dam region by the United States Geological Survey for the United States Bureau of Reclamation' in the spring of 1934. Mr. D. F. Hewett, who had general charge of the investigation, Mr. W. T. Schaller and Mr. M. I. Goldman contributed many helpful suggestions. Mr. N. H. Harshman assisted efficiently during the field work.

Jan 1, 1935

A special war committee of the Engineering Council has been appointed to assist other committees of the United Engineering Societies having to do with the development of the arts and sciences related to warfare. One of the principal functions of this additional committee is to pass upon the probable value of new inventions. The new committee has established headquarters' in the rooms of the Naval Consulting Board in New York City, and has received the franking privilege of the Post Office Department.

Jan 1, 1918

By Bernard Moore

AT present the demands of the United States for strontium are met by imports from Germany, England and Canada, which vary considerably in proportions of ore and finished salts, in tonnage and in value. Statistics for the period 1926-1932 are given in Table 1. Domestic deposits are TABLE 1.-Strontium Imported into the United States, 1926-1932a Ore Chemicals Year Short Tons Value Pounds Value 1926 2,200 $58,159 5,433,044 $115,436 1927 1,356 58,711 4,233,816 149,383 1928 759 31,157 3,380,464 136,561 1929 973 45,505 4,578,327 196,233 1930 220 10,459 2,153,788 104.807 1931 (260 lbs.) 123 1,742,714 83,564 1932 5 276 469,481 20,910 a Mineral Industry (1934) 42, 61. known in many states, but the, larger and purer ones are in the West, particularly in the desert region of southeastern California and western Arizona. These deposits are large enough to command interest, par-ticularly in consideration of future cheap power at the Boulder Dam. The deposits described in this paper were examined during an investi-gation of the mineral resources of the Boulder Dam region by the United States Geological Survey for the United States Bureau of Reclamation in the spring of 1934. Mr. D. F. Hewett, who had general charge of the investigation, Mr. W. T. Schaller and Mr. M. I. Goldman contributed many helpful suggestions. Mr. N. H. Harshman assisted efficiently during the field work.

Jan 1, 1935

By R. C. Hall

In the present work, experiments determined the effect of the order-disorder reaction near the Fe,Al composition on the magnetic anisotropy and magnetostriction of single crystals: A material which is more difficult to magnetize in one direction than in another is anisotropic, that is, the ease with which ferromagnetic materials may be magnetized in different crystallographic directions determines the anisotropy. Two investigators have estimated the anisotropy of the aluminum iron alloys from poly-crystalline data;1,2 however, these estimates should not be considered to be reliable. Siege1 made two accurate measurements of the first anisotropy constant* from single crystals of 4.0 wt pct aluminum sotropy throughout the ferromagnetic aluminum iron system have been described. These results were obtained from single crystals which were slowly cooled and, hence, ordered near the Fe3Al composition.4 Magnetostriction is the change in length per unit length resulting from applying a magnetic field to a ferromagnetic material. For the purpose of this report, the saturation magnetostriction was measured. This is the maximum change in length per unit length resulting from an applied magnetic field large enough to saturate the material in a given direction. This magnetostriction has been determined for single crystals of the ferromagnetic aluminum-iron system.' The crystals near Fe3Al were also ordered. PREPARATION AND TREATMENT OF SINGLE CRYSTALS Single crystal bars were grown from the melt.' The raw materials for these crystals were iron and aluminum of 99.9 and 99.99 pct purity, respectively. From the bars, crystals in the shape of circular

Jan 1, 1959

By Joseph William Pinder

Every millman engaged in the operations incident to the handling of crushing-rolls knows that in ordinary practice, when fine product is desired, the ore-materials delivered to the machine, divided into four sizes, may be estimated, approximately, as follows : Per cent. Papsing a 4-mesh screen,..40 2- " " ........30 " 3/4-inch-mesh screen,.. 20 Larger,...........10 This estimate refers more particularly to the requirements of medium-sized rolls and fine crushing. But, depending largely on the character of work to be performed, the coarser material is often larger and of a greater percentage, while the bulk is always more or less fine.

Jan 1, 1899

By Frank Doxey

AT Dominion Steel & Coal Corp. it has long been recognized that continued mechanization of mine operations is necessary in the Pictou, Cumberland, and Sidney coal fields of Nova Scotia. The varied physical conditions in these fields call for special consideration of individual cases before planning is finalized. Because standard equipment cannot be procured which would operate successfully, many experiments have been necessary over the years to keep pace with the progress made in other countries. There are two mines, producing 2000 tpd, located in the Pictou coal field. The field is badly distorted and crossed by many faults. Seams are highly inclined and irregular and vary in thickness from 5 to 40 ft. Entries are difficult to maintain because of squeezing of the coal. ribs and movement of the roof and pavement. Output from the three operating mines in the Cumberland field is 3000 tpd. The field is highly inclined, inclination varying from 12° to 32°. Overlying beds consist of shales and massive sandstone lenses of extreme toughness and are responsible for bumps when the stresses are relieved by extraction. At greatest depth these are among the deepest coal workings in the world. Depth of cover ranges from 2300 to 4000 ft. This prohibits room-and-pillar working and necessitates longwall operation. Working of contiguous seams concurrently to maintain output increases the already difficult conditions. The Sydney field, with a frontage of about 30 miles, is the most important of the Nova Scotia coal fields. With the exception of one small area it is now wholly submarine. Output is approximately 21,000 tpd. Seams are 21/2 to 8 ft thick, and cover in the areas varies from 600 to 2300 ft, with an average of 1500 ft from sea bottom to the top of the seam. The seams dip in a seaward direction, pitches ranging from 6" to 4.0". The shoreline is the last place of entry to the seams and distance from the bank to the working faces is generally over 3½ miles, in some cases as much as 6½ miles. Ventilation is a problem and requires the construction of large permanent airways. Getting and Loading Coal: In 1925, in view of heavy pressures exerted by thickness of cover overlying the seams, roadways and pillars of the room-and-pillar system being worked began to break up and coal was lost. It was decided that a change in the method of extraction in areas with heavy cover was necessary, and experiments were made with many short walls and longwalls varying between 90 and 250 ft. Trial and error proved that the best operating length was between 400 and 500 ft, delivering all coal to the dip, with roadways to the face following a level course. The change-over was gradual, and the technique of roof control developed with the system, so that falls to the face are now very infrequent. An advantage of longwall mining is that it yields 95 pct extraction, especially important in coal seams of high quality or in seams where faults or disturbances restrict the workable areas. This percentage of extraction is based on the fact that the longwall advancing system takes development faces where pitch permits instead of driving headings and leaving roadway pillars. This system yields high tonnage during development and limits loss in extraction to duff left during operations. Accompanying disadvantages, on the other hand, are the heavy construction cost of main roadways and the necessity of driving all new flank face roadways through the gob. If the main roadways are driven through the solid, and large enough pillars are left on each side for protection against flank face weights, then the width of solid coal is approximately 1700 ft. This represents 10.6 pct of the coal available, or 89.4 pct extraction of the whole. These pillars, however, are of such size that they provide a useful pillar drawing area as a final operation of the mine. It may be that although the seam cannot be generally mined by the room-and-pillar method, it can be adapted to

Jan 1, 1955

By T. W. Guy

DURING recent years, tremendous strides have been made in the economical use of coal. This has resulted in, and to some extent has been a result of, making the fuel specifications more and more rigid. For this reason, all producers have found it necessary to improve their preparation materially, both as to sizing and the elimination of impurities, either by more effective preparation underground or at the tipple and cleaning plant, or both. This cause and its effect in all producing fields seem likely to continue for several years-at least. The splendid inherent qualities of the Pocahontas and New River coals are known all over the world, but their good reputation is only partly due to inherent qualities, and to natural conditions which generally favor loading coal comparatively free from impurities; it is due in large measure to the care and skill used, either with or without the aid of mechanical devices, to ship products consistently low in ash. The first coal from the West Virginia smokeless fields was mined and shipped near Quinnimont, on New River, in 1871, while the first shipments from the Pocahontas field were in 1883. The development of both fields progressed rapidly. At first activities followed the main lines of the Chesapeake & Ohio and Norfolk & Western railroads, and were extended later as branch lines were built from these roads. The Virginian R. R., about 1907, opened up the Winding Gulf territory, which has since become a large producer of smokeless coals from the Pocahontas and the New River measures.

Jan 1, 1931

By Cuppam Dasarathy

THE object of this note is to report briefly certain results of investigations on the Fe-In phase diagram. BISRA-high purity H-iron and 99.9 pct pure indium were used to prepare the alloys. The experimental techniques consisted of thermal analysis, optical metallography, and X-ray diffraction. A phase diagram based on the present results as well as those reported earlier by the author' is shown in Fig. 1. It is seen that the liquidus points fall on a smooth line which meets the monotectic isotherm at 1470°C. The liquidus extends up to 3.4 at. pct In. The phase boundary separating the two liquidus L1 and L2 is shown dotted. The experimental solidus meets the monotectic isotherm at -0.9 at. pct In. The 6/6 + L2 boundary drops steeply to the 6 + La/y + L2 boundary at -1350°C. In this region, it is impossible to detect satisfactory thermal arrests because of the steep phase boundary. The present diagram shows that indium lowers the temperature of the d/y transforma-tion and raises the temperature of the y/a transfor-mation. The y +d region is found to be very narrow. Indium gives rise to a restricted y field when alloyed with iron. The width of this field is between 0.4 and 0.5 at. pct In. Details of the alloys containing 40 and 50 at. pct In have already been reported by the author' and the transformation temperatures of these alloys are included in Fig. 1. It appeared from optical metallography and X-ray diffraction that the room temperature solubility of indium in a iron is less than 0.28 at. pct since alloys of 0.28 at. pct In and above, slow cooled to room temperature, contained dark etching second phase particles situated both in the matrix and grain boundaries of the a-grains, see Figs. 2 and 3. These particles were identified to be unalloyed indium by X-ray diffraction. The lattice parameter of the a phase reached a maximum of 2.8672A at the indium level of -0.28 at. pct. The present diagram, Fig. 1, is in substantial agreement with that of Stadelmaier and Fiedler' except for certain differences in detail. For example, they found the monotectic composition and temperature to be 7.0 at. pct In and 1443oC, respectively, while the present work indicates them to be 3.4 at. pct In and 1470°C. The 6 + L2/y + L2 transformation is indicated in the present work to occur at -1350°C, whereas Stadelmaier and Fiedler find this to occur at -1320°C. They also claim that the width of the y field is 0.2 at. pct In while the present work shows the width to be between 0.4 and 0.5 at. pct In. 1) Indium, when alloyed with iron, gives rise to a restricted y field, the width being >0.5 at. pct In.

Jan 1, 1970

By Jean Howard

RECENT attempts to produce secondary recrystalli-zation in high-purity iron have given conflicting results. Coulomb and Lacombe1'2 did not find it but Dunn and Walter3,4 did. The latter workers have stated that (100) [001] and/or (110) [001] orientations develop depending on the oxygen content of the annealing atmosphere. This Technical Note records results which are in agreement with Dunn and Walter in so far as it shows that secondary recrystallization can be produced in high-purity iron, but does not confirm that both types of orientation are obtainable. Similar observations have been made on chromium-iron and molybdenum-iron, although when this technique is used on 3 1/4 pct Si-Fe, both types are obtained as in the work of Dunn and alter.' Pure iron strip was cold-rolled from sintered compacts prepared from Carbonyl Iron Powder-Grade MCP of the International Nickel Co. (Mond) Ltd. The powder contains about 0.5 pct 0, 0.01 pct C, 0.004 pct N, (0.002 pct S, $0.005 pct Mg and Si, and 0.4 pct Ni—that is, it is substantially free from metallic impurities other than nickel, which is thought to be unimportant in the present work. The iron powder was (a) pressed at 25 tons per sq in. into blocks measuring 3 by 1 by 0.3 in., (b) deoxidized in hydrogen (dewpoint -60°C) by heating first at 350°C and then at 600° C until the dewpoint returned to -60°C at each temperature and (c) sintered in hydrogen (dewpoint -40°C) at 1350°C for 24 hr. (when dewpoint is referred to in this Note, it is the value as measured on the exit side of the furnace). The sintered compacts were cold-rolled to 1/8 in., annealed in hydrogen (dewpoint -60°C) at 1050°C for 12 hr and cold-rolled to 0.004, 0.002, and 0.001 in. with inter-anneals at 900°C for 5 hr and a final reduction of 50 pct. Final annealing of strip between alumina or silica plates at 875" to 900°C in hydrogen with dewpoints of -20°, -55" and -80°C produced secondary grains with the (100) in the rolling plane; the extent of secondary recrystallization was greatest when the dewpoint was -55°C. Annealing in a vacuum of 2 x 10"5 mm Hg at the same temperature produced no secondary recrystallization at all. With strip thicker than 0.002 in. very few secondary crystals developed whatever the conditions of annealing. Using a processing schedule somewhat similar to that described above, secondary recrystallization was produced in two bcc alloys of iron, viz. 80 pct Fe + 20 pct Cr and 96 pct Fe + 4 pct Mo. The former was reduced to final thicknesses of 0.001 to 0.004 in. and the latter to final thicknesses of 0.001 to 0.016 in. With the chromium-iron, a final anneal at 1250°C (found to be the most effective temperature for developing secondary crystals in the 0.004-in material) with a dewpoint of -25°C produced a greater degree of secondary recrystallization than with dewpoints of -50°C or -20°C. Secondary crystals developed in strips of all thicknesses from 0.001 to 0.004 in. Final annealing in vacuum produced no secondary crystals at all. For the molybdenum-iron a temperature of 1200°C was most effective. It was found that a dewpoint of -50°C during the final anneal gave better results than a dewpoint of -25 "C on the 0.008 in. material. Final annealing in vacuum gave slightly worse results than annealing in hydrogen with a dew-point of -50°C. Secondary crystals were developed in strips of all thicknesses up to 0.008 in. The experiments show that the extent of secondary recrystallization is a maximum for certain critical values of oxygen content of furnace atmosphere and annealing temperature, and that these values are different for different alloys. The thinner the material, the less critical these values are. The general conclusions are that secondary recrystallization can be obtained in high-purity iron, chromium-iron, and molybdenum-iron, using a processing schedule similar to that which will cause the phenomenon to take place in high purity 3 1/4 pct Si-Fe. Unlike the silicon-iron, however, only the (100) (0011-- orientation has been produced in these alloys, irrespective of the temperature of final annealing and the oxygen content of the furnace atmosphere. The information used in this Note is published by permission of the Engineer-in-Chief of the British Post Office.

Jan 1, 1962

By Arnulf Muan, Hobart M. Kraner

Ferromanganese alloys react with aluminu-silica brick in blast furnace hearths and cause the formation of new phases with low refractoriness and consequent failure of the refractory lining. The nature of these reactions is explained on the basis of petrographic observations, thermodynamic data, and Phase equilibrium considerations. Animproued hearth design resulted from these findings. The production of ferromanganese in blast furnaces presents many problems which are not encountered in the production of iron in the same furnaces. One of the most serious of these problems is the rapid failure of refractories caused by their reaction with the ferromanganese metal. The present paper describes such a "hearth attack", its symptoms, causes, and cure. Following an introductory discussion of operating practice in ferromanganese blast furnaces, results are presented of a petrographic examination of samples from a furnace which had to be shut down because of refractory failure. The causes of this failure are then analyzed on the basis of petrographic observations combined with thermodynamic and phase equilibrium data available in the literature. The latter type of data were subsequently used as a guide in recommending improvements in hearth designs which have since proven themselves successful in practical operations. I) FERROMANGANESE BLAST FURNACE PRACTICE It is considered good practice to blow in a furnace on iron and operate it in this way for a period of time preliminary to producing ferrornanganese. During this time, iron generally penetrates the bottom refractories six or more feet below the original working surface of the hearth. Not only does this metal pervade the joints to these depths, but the pores of the refractories are usually also filled by molten iron. The high throughput of the iron furnace provides ample heat to maintain a high temperature in the hearth refractories. This, together with a high ferrostatic pressure, causes porous clay brick of the hearth to shrink. During subsequent use of such a furnace in ferromanganese production, the iron in the pores of hearth brick if; replaced to some extent by ferromanganese. The replacement is usually not complete. This is probably due to the lower metal throughput and lower prevailing temperatures resulting from this in the brick of the hearth bottom. When the ferrornanganese furnace is banked—or when the temperature in the furnace falls due to a furnace delay—-manganese oxidizes even though the atmosphere is largely CO. Considerable expansion accompanies this oxidation of manganese from metal to oxide. The hearth refractories are then subjected to the disintegrating forces of the volume expansion. These forces may in extreme cases be large enough to lift the furnace off its mantle supports as was described in a previous paper.' When cooling takes place slowly, however, and the temperature remains at a fairly high level, the refractories undergo fluxing action by the MnO. This latter reaction and the reduction of SiO2 of the clay brick is the general subject of the present paper. The observations to be described herein were made on a ferromanganese furnace located at the Johnstown plant of Bethlehem Steel Co. The furnace was lined entirely with clay refractories and had operated on iron for 266 days and on ferromanganese for 96 days prior to being taken off because of a hearth wall failure. II) PETROGRAPHIC EXAMINATION AND CHEMICAL ANALYSIS The photograph reproduced in Fig. 1 shws a cross section of the upper part of an 18 by 9 by 4-1/2 in. bottom block removed from the blast furnace. This brick came from a depth of approximately 6 ft below the original working face of the bottom. It will be noted that the 4-1/2 in. dimension is almost the same as when the brick entered the furnace. Three characteristically different zones marked I, II, and III on the print of Fig. 1 are apparent. Results of chemical analyses of the original brick and samples from each of these zones are listed in Table I. Petrographically the various zones were characterized as follows: The central zone marked I was essentially un-reacted brick. The microstructure consisted of fine needles of mullite, and the pores in this entire area were filled with iron. This is characteristic of

Jan 1, 1962

By E. B. Burwell, R. H. Nesbitt

A NEW milestone in the progress of photography and subsurface exploration was reached when the Chief of Army Engineers announced the development of the NX borehole camera. In obtaining continuous undistorted cylindrical color pictures of dry or water-filled borings the device surpasses all other cameras designed for photographing interior surfaces of pipes, wells, and conduits. The usefulness of the camera and the unique projector that comes with it are at once apparent. To the geological, mining, and civil engineer alike it signifies the end of guesswork with respect to underground conditions that have eluded identification by conventional core-drilling methods. To the medical profession it may well signal new progress in photo optics which could result in cylindrical color photographs supplementing the X-ray and existing photographic methods used in exploratory surgery.

Jan 8, 1954

By John E. Conley

THE slate industry of the United States has shown a marked decline in value of products made annually since the peak year 1925, although there has been moderate improvement over the lean years 1932 to 1934. In 1940, the value of all slate products sold was approximately 5 3/4 million dollars for a total output of 473,450 short tons. The quantity sold was a little less and the value a great deal lower than the annual averages for the past two decades. Enormous quantities of waste materials result from the quarrying, splitting and milling of slate. Obviously, utilization of such waste material is desirable, not only from the viewpoint of economical operation but also for the purpose of conserving natural resources. One possible use is to produce expanded or puffed lightweight aggregate for use in concretes. Such concretes are strong enough for specific uses, and the advantage of lightness could be obtained in such structures as the walls and roofs of buildings, suspension-bridge roadways and various other applications where weight is a factor. Conceivably, these uses could consume an appreciable annual tonnage. USE OF WASTE SLATES FOR MAKING AGGREGATES The lightweight-aggregate industry has been discussed elsewhere4.5 and need not be covered in detail in this paper. The materials commonly utilized are naturally occurring aggregates such as volcanic cinder, tuff and pumice; by-product materials, such as ordinary cinders and air-cooled slags; and the specially manufactured products, including Haydite, Pottsco, Gravelite, Cel-seal, Superock and Waylite. Slates, however, have not been given the consideration they merit, especially in the United States. In the British Isles, some work has been done' on certain Welsh slates by the Building Research Station to stimulate the use of these wastes. REQUIREMENTS FOR RAW MATERIALS As pointed out by Hughes,4 the lightweight-aggregate industry is segregated in regions adjacent to large cities in order to localize the market and avoid the necessity of long freight haulage. Waste slate from the deposits of eastern Pennsylvania, northern Maryland, and Virginia would meet the basic requirement of any low-priced structural raw material. One apparent advantage is attained when slate waste, normally discarded, is utilized in the manufacture of a by-product. Mining or quarrying costs usually have been assessed against the main product. Some additional grinding might be desirable, but this operation would be relatively cheap, as most slates grind easily. It is believed that virtually all slates, when properly heated, will expand to some degree. However, types that will expand from 3 to 7 times their original volume are preferred. Fig. I illustrates the expansion of a Pennsylvania slate. The cube originally

Jan 1, 1942

By Persifor Frazer

TILE ore property of Mr. Augustus Roop is situated about one and a half miles south of the New Windsor Station of the Western Maryland Railroad and is connected with the town of New Windsor by the Liberty and New Windsor Turnpike. It is about forty miles distant from Baltimore, and about seven miles west from the county town of Westminster, and a little more northeast from the celebrated Liberty Copper Mines. (See accompanying Maps 1 and 2.) The property comprises about 140 acres, lying principally

Jan 1, 1881

By John Blandy

EVERY new mining district has had its own peculiar experiences in inventing and experimenting upon new methods for the various operations of mining, and more particularly in the processes of crushing and dressing ores. As a matter of course, during this period many old things have been reinvented, patented, and cast aside, there to remain until at a future day other geniuses shall bring them forth again as new. In this respect the Copper Region of Michigan has not been behind other mining centres, and probably in no other part of the country has more money been expended in devising new machines and improvements upon old ones for the crushing of the rock. The appliances for washing the sand have not been so varied, simply for the reason that, having but one mineral, or rather metal, of high specific gravity to separate from rock material which varies but little in its character in any one mine, it requires much less care than is necessary in most mining centres of the world. At the beginning of operations in that district most of the work was in the control of Cornish miners, who introduced the simplest of Cornish mills, namely, wooden stem pestles, with wooden shafts and cams. These were well suited to the small mines, and particularly to the limited means of transporting more expensive machinery. As these facilities improved, they were enabled to change to iron, and to vary their patterns of rods, shafts, cams, and mortars. The most approved pattern, finally obtained, is the square or round stem, with collar adjustable by means of keys. In its present form it is a bar of cold rolled shafting, an eye in the top, an adjustable collar with key-plate and keys, the head and a shoe of chilled iron. The stem is fitted into the head by a slight taper. The battery has heretofore been of wood, lined with chilled cast plates, and bed-plate of the same, but within the past year the California pattern has been introduced. The screens are of sheet-steel, drilled with 16 holes to the inch. During this period of trial and gradual improvement in the pestle stamps, in the years 1855-6, the Ball steam-stamps were intro¬duced, and after years of labor and expense, have been made the most efficient and powerful machines ever yet used for the purpose. It is ostensibly the Nasmyth steam-hammer, and yet the

Jan 1, 1874

By AIME

Generally speaking, the mining industry had a good year in 1948 with most mineral products being produced in record quantities for peacetime standards. The big boys-iron and steel, coal, and petroleum-indicated the industry-wide trend by surpassing 1947 production figures. Although exploration and expansion are being pushed aggressively in all branches of the industry, there is a pronounced trend to engineering and research directed at cutting production costs, improving the product, and finding new markets. These improvement campaigns are making headway; in the bituminous coal industry, 5.43 tons per man employed is the new production record; 83 million tons of iron ore were unloaded at lower Lake ports, breaking another peacetime record; magnesium, due to improvement in manufacturing techniques, now competes on the market with aluminum.

Jan 1, 1949

1876, PROF. RICHARD AKERMAN Stockholm, Sweden. 1913. DR. FRANK DAWSON ADAMS Montreal, Canada. 1909. PROP. RICHARD BECK Freiberg, Germany. 1905. ANDREW CARNEGIE New York, N. Y. 1906. DR. JAMES DOUGLAS New York, N. Y. 1888. PROF. HATON DE LA GOUPILLIERE Paris, France. 1966. SIR ROBERT A. HADFIELD London, England. 1888. PROF. HANS HOEFER Leoben, Austria. 1917. HERBERT C. HOOVER San Francisco, Cal. 1915.. JAMES FURMAN KEMP NEW York, N. Y. 1905. PROF. HENRI LOUIS LE CHATELIER Paris, France. 1913. EZEQUIEL ORDONEZ Mexico City, Mexico. 1909. ALEXANDRE POURCEL Paris, France. 1911. DR. ROSSITER W. RAYMOND New York, N. Y. 1911. PROF. ROBERT H. RICHARDS Boston, Mass. 1909. DR. ING. H. C. EMIL SCHROEDTER Dusseldorf, Germany., 1906. JOHN E. STEAD Middlesbrough, England. 1902. PROF. DIMITRY CONSTANTIN TSCHERNOFF Petrograd, Russia. 1910. PROF. TSUNASHIRO WADA Tokyo, Japan. 1907. CHARLES D. WALCOTT Washington, D. C.

Jan 1, 1917

By Fred P. Dewey

The product of the Muirkirk, Md., furnace has always enjoyed a very high reputation for strength ; and this is supported not only by its behavior in practice, both alone and in mixtures, but also by the following series of tensile tests, made at various times during the last fourteen years: South Boston Iron Co., November loth, 1874. Strength. Pounds Grade. per square inch. Density. No. 3,....... 30,685 7.2794 No. 4,....... 35,140 7.2713

Jan 1, 1889

By Persifor Frazer

The ore property of Mr. Augustus bop is situated about one and a half miles south of the New Windsor Station of the Western Maryland Railroad and is connected with the town of New Windsor by the Liberty and New Windsor Turnpike. It is about forty miles distant from Baltimore, and about seven miles west from the county town of Westminster, and a little more northeast from the celebrated Liberty Copper Mines. (See accompanying Map I and 2.) The property comprises about 140 acres, lying principally

Jan 1, 1881