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By J. D. Anthony

The Australian continent possesses significant reserves of a wide range of minerals, including bauxite, coal, copper, diamonds, gold, iron ore, lead, manganese, mineral sands, nickel, phosphate, silver, tin, uranium, and zinc. Australia's identified economic resources of many minerals are very large as indicated in Table 1. A sophisticated and highly experienced mineral industry is now an established feature of the Australian economy and Australia is the world's largest exporter of iron ore, alumina, mineral sands and refined lead and amongst the leading suppliers of many other commodities such as coal, lead and zinc ores/concentrates, nickel, refined zinc, tungsten concentrates and bauxite. The industry exports 70% of its production. This is reflected in the value of Australian mineral exports which have grown from about $200m in 1960/61, comprising 10% of total export receipts, to about $1265m or 29% of export income in 1970/71 to around $7061 representing 37% of Australia's total export income in 1980/81. Details of the more significant minerals are as follows: Japan (42.1%) USA (11.3%) ASEAN (6.3%) UK (5.9%) F.R. Germany (3.8%) Republic of Korea (3.4%) New Zealand (2.6%) Also see Table 2. AUSTRALIA'S MINERAL RESOURCES POLICIES Federal and State Governments' Responsibilities Australia has a federal system of government comprising six States, a self-governing Territory and a Federal Government. Under the Australian federal system the Constitution sets down the powers of the Federal Government. All powers not assigned to the Federal Government in the Australian Constitution reside automatically with the States. Certain of these broad powers result in the Federal Government having a significant influence on resources development. For example, in being responsible for economic management, the Federal Government's fiscal and monetary policies have an important effect on industry as well as on State finances. In particular, the taxation regime employed by the Federal Government is of direct importance to decision-makers in the resources industry. The Federal Government is responsible also under the Constitution for external trade matters; and international trade and commodity matters are increasingly important in Australia's international relationships. Foreign investment is another area where the Federal Government has a role to ensure that national interests are protected. This foreign investment power flows from the Federal Government's control of foreign exchange movements into and out of Australia. However, before enlarging on these and others of the Federal Government's powers and policies, it should be emphasized that the State governments, by virtue of their wide powers to regulate matters within their own boundaries, are more directly involved in the day-to-day administration and regulation of mining operations. For instance, the powers of the State governments include the responsibility-for the granting of exploration rights and mining leases, the approval of mining operations and the levying of royalties and other like charges. Administrative arrangements covering the granting of minerals and petroleum exploration and development titles vary from State to State. Before development rights are granted, State governments consider environment protection and rehabilitation aspects of development proposals. The provision of infrastructure within State borders is a matter primarily of State government responsibility. It is usual practice in Australia for State governments to construct and operate infrastructure services such. as railways, ports and electricity generation and transmission. The States may also provide certain public services such as electricity. and water, port and loading facilities, communications, health and education services which form part of the infrastructure of mining operations. In remote areas the mining companies themselves usually are expected to provide much of this infrastructure. However, the Federal Government is primarily responsible in some fields, such as telecommunications and parts of the railways network. State governments carry out preliminary exploration and geological mapping and some are directly involved in the mining of coal for power generation. The Federal Government's responsibilities in addition to economic management, taxation, international relations, foreign capital and investment, include regulation of exports, environmental matters and matters affecting the Aboriginals of the Northern Territory. FEDERAL GOVERNMENT POLICIES The continued sound development of the minerals and energy resources sector is regarded by the Federal Government as being of very great importance. However, the Government does not seek to participate directly in resource developments. It sees its role rather as that of establishing a sound economic and policy climate in which private companies can identify opportunities, seek out customers and marshall the necessary capital for the development of resource projects.

Jan 1, 1982

By William G. Pariseau, H. Douglas Dahl

Recent subsidence legislation indicates that mining engineers would be welt advised to be able to predict and control surface damage caused by mine subsidence. To date, such an ability is practically nonexistent. Model analysis is suggested as one of the alternative paths available which might yield fruitful results. Similitude requirements developed for a self-loaded body in static or quasi-static equilibrium indicate that complete similitude without centrifuging is an impracticability. However, a pilot experimental study which used a simplifying assumption to correctly model mine subsidence has produced results in qualitative agreement with field observations. The purpose of this paper is to present a discussion of the various approaches that can be taken in the study of mine subsidence phenomena. Particular attention is focused upon the rational selection and use of laboratory models. Broadly interpreted, mine subsidence is the deformation of the rock mass enclosing a mine. Depending upon a number of factors, the movement of the subsiding rock mass may disrupt gas and water lines or other buried utilities, damage surface structures such as buildings and bridges, dislocate streams, roads, and rail lines, aggravate acid mine drainage and fire problems, and generally mar the landscape. It is clearly a problem that no mine manager can safely ignore. It is also a problem that will grow with the general population increase. In the following discussion, a summary review of past and present approaches to subsidence studies is given. The possibilities of duplicating subsidence phenomena in laboratory models are examined, and an analysis of a particular type of model is presented. Some preliminary results obtained from a model of the particular type analyzed are then discussed. REVIEW OF PREVIOUS WORK Historically, subsidence investigations have been empirical studies in the field and laboratory or theoretical analyses of mathematically idealized media. Empirical and theoretical work in the United States has generally lagged behind investigations abroad. In the United States, field studies are mostly pre-World War 11. These are summarized in the Mining Engineer's Handbook. ' Field studies in Europe are more recent and more extensive. Those made in Great Britain are summarized in the Subsidence Engineers Handbook2 and represent observations made at 157 different collieries. Such studies by themselves are of limited usefulness as are all empirical studies. One can never be certain that conditions at one mine will be similar enough to those at another to warrant the drawing of like conclusions. European subsidence formulas rely heavily upon the "angle of draw" and "critical area" concepts. The angle of draw is defined as the angle between a vertical line through the face, and another line extending from the face to the surface at the point where movement is zero. The critical area is defined in relation to the least extraction necessary to produce maximum subsidence. Fig. 1 illustrates the angle of draw and critical area concepts. First and second "limits of influence" are also shown. The angle of draw and associated critical area concept are obviously not well defined, being dependent upon the accuracy of the surface survey. In Great Britain, the angle of draw has increased through the years from about 26 to 35°. In the United States, zero and negative angles of draw have been reported. In the authors' opinion, these purely geometrical concepts represent an oversimplification of subsidence phenomena and their use, in the United States at least, should be discouraged. Empirical observations of laboratory models containing layers of earth, sand, clay, and plaster were made by Fayol (cited by Peele) as early as 1885. An outgrowth of his work was the "dome theory," a verbal description of what is assumed to occur in subsiding rock masses. The dome theory has since fallen into disrepute. Theoretical analyses worthy of the name treat a subsiding rock mass as a deformable body. In these analyses, the actual rock mass is replaced by an idealized material that deforms according to a simple stress-strain relationship. The stress equations of equilibrium expressing the Newtonian laws of mechanical action and the geometry of strain furnish additional equations that must be satisfied. A loading criterion-generally understood, and in some cases stated explicitly-completes the theory.

Jan 1, 1969

Jan 1, 1940

By Ove Rehnberg

Catalytic purifiers are widely used as exhaust treatment devices on diesel equipment in confined spaces. The paper summarizes some studies carried out at the University of Lulea on diesel exhaust purifiers. The main purpose has been to elucidate important chemical activities of catalysts useful for the improvement of their effect. The effects of platinum catalysts on exhaust constituents such as carbon monoxide, nitrogen oxides, unburned gaseous hydrocarbons, and polynuclear aromatic hydrocarbons are discussed. Also pointed out are the great differences in catalyst activity and advantages/disadvantages associated with the catalysts.

Jan 1, 1982

By L. L. Karafiath, S. G. Vick, E. A. Nowatzki

Computer analyses of the trafficability of copper mine tailings by four different commercially available BWEs were performed. A mathematical model incorporating the tailings' Coulomb strength parameters and the vehicles' geometry and operational characteristics was used to study the vehicle terrain interaction. The computer output provides the maximum tractive force (net drawbar pull) that each BWE can develop for given tailings conditions without bnngzng about a state of plastic failure in the tailings. Estimates of sinkage are also provided. The theoretical results for the BWEs and tailings studied compare favorably with the operating experience of similar BWEs used for remining gold tailings in South Africa. This lends some confidence to the validity of the mathematical model. The results of such analyses may be wed to evaluate, on a relative basis, which of a number of different machines would perform better than others under given conditions of a tailings deposit.

Jan 1, 1982

NEW MEMBERS The following list comprises the names of those persons who became members during the period May 10 to June 10, 1915: Members ANDREEN, HARRY MAYO, Millman: and Assayer Thane, Alaska. BANKS, HUBERT RAYMOND, Min. Engr., Mill Staff, Consolidated Arizona Smelting Co., Humboldt, Ariz. BASSETT, ARTHUR F., Min. Engr., Care Consolidated Arizona Smelting Co., Humboldt, Ariz. BLACKNER, LESTER A., Slope Engr.... Care Ray Consolidated Copper Co., Ray, Ariz. BUSHNELL, C. E., Draftsman Butte & Superior Copper Co., Butte, Mont. CAVAGNARO, DAVID AMILE, Min. Engr., Genl. Supt., Wisconsin North Fork GravelMines, Forest, Sierra Co.; Cal. COGHILL, WILLIAM HAKES, Met., Ore Testing Laboratory, 3705 Hueco St., - - El Paso, Tex.

Jan 7, 1915

By C. M. EYE

IN the spring of 1905 I was employed by Messrs. Bradley and Requa, under our fellow member, Thomas Cox, on the mill plans for the Nevada Consolidated, when an opportunity came to go to the Philippines to erect a small mill on the property of the Benguet Consolidated. This I accepted, expecting to be away eight months or so, but it was seven years before I got back. .I sailed in May, on the Coptic, having as room-mate as far as Kobe, A. E. Drucker, who was going out to Korea for the Oriental Consolidated. It was the first trans-ocean trip for either of us, and we had some rather unusual experiences. This was toward the close of the Russo-Japanese war and the Russian fleet was known to be on the way from Suez to Asiatic waters, but it was a matter of doubt whether they would risk a passage between Japan and the mainland, or take the longer but obviously safer route outside of Japan. The Coptic carried much contraband of war for Japan, so naturally did not care to meet this fleet. No definite word being available at Honolulu, we went to the Midway Islands, but the cable station there had very little information to offer, so we proceeded cautiously toward Japan. On the last afternoon out, we steamed due north at half speed for several hours, and finally sneaked into Yokohama at night, to learn that ' the Russian fleet had met the Japanese the day before and had been annihilated. We sailed over the spot in the Sea of Japan a week later, and when we got to Manila we found three of the Russian boats interned and being guarded by the monitor Monadnock and a cruiser. This was only a matter of form, as the Russians were only too glad to be there for the rest of the war, and the boats could not have gone far anyway, for they were literally shot to pieces. The Admiral's flagship had a hole within 3 ft. of the water line, for ward, through which a man could enter by stooping.

Jan 1, 1929

By R. G. Treuting, W. C. Ellis

The twinned state is characterized by a lattice of coincidence sites. Imperfections are required at stable lateral twin interfaces. Twinned regions can occur with relative ease in the diamond cubic IN recent contributions1,2 on the origin and growth of cubic annealing twins, attention has been directed to the orientation relations between such twinned components and their parent matrix. There are some aspects of twinning which may be illuminated by a more detailed consideration of the twinned state" alone. As an extreme example, the dense twinning in cast ingots of germanium,&apos; as contrasted with the rarity of twins in cast face-centered cubic metals, is yet to be accounted for. It has been this that has led us to the present work, which, it will be noted, uses methods and constructions in many respects similar to those of Kronberg and Wilson.&apos; In the cubic systems, a 70" 32&apos; rotation about a <110> axis is angularly equivalent, as to twinning, to the more usually considered 180" rotation about a <111> axis. Figs. 1 and 2 show a (110) projection of a twinned face-centered cubic lattice and a twinned diamond cubic lattice. In both figures, the two adjacent planes A and B, shown by the larger and smaller circles, are sufficient to represent the entire array. In each case a section of lattice, the original atom sites of which are shown by open circles, has been rotated as indicated through 70" 32&apos; to bring an original. [112] direction into coincidence with the [112] diiection. The latter is the intercept on the (110) projection of the (ill) plane normal thereto, the twinning plane. In the face-centered cubic case the rotation can be performed about an axis passing through an atom-site; the mirror plane then is also a composition plane containing atoms common to both twinned and untwinned lattices. The diamond cubic lattice may be construed as two interpenetrated face-centered lattices. Its (111) planes recur in a sequence of alternately short and long interspacings. Consequently a mirror plane for twinning cannot be a composition plane, but must be the bisector of one of the spacings. When the longer spacing is selected, the closest distance of approach across the mirror plane in the [ill] direc- tion is identical with that in the untwinned structure. In each case periodically recurring (ill) planes (parallel with the twinning plane) are found, on which there is coincidence of atom sites of the pre-twinned and twinned orientations; these are indicated by the cross-hatched circles. In the face-centered lattice there is such coincidence every third (ill) plane; in the diamond cubic lattice, on two adjacent planes in every six. At the twinning interface in the latter, there is on each side of the mirror plane a (ill) plane of atoms common to both twin components. Conceivably, there is little influence on a plane of atoms about to be adhered to such a pair of coincidence planes, whether it be laid down in a normal or in a twinned position with respect to the previously formed structure. Slawson% as attributed the high incidence of twinning in diamond to this boundary state. Further examination shows that the motion of intermediate planes can consist of various pairs of equal and opposite translations, for example of (ill) planes in the [l&apos;;i2) direction, the familiar twinning shear, indicated in the small schematics in the figures. Since the translations form a system of shears of alternating sign between coincidence planes, twinning could take place by such a mechanism over an extended region without extensive shear; in fact, in this case any atom moves but the distance in the [1i2] direction. One alternative construction for the face-centered cubic lattice leading to the same end result is illustrated in Fig. 3. The plane (711) with respect to the pretwinning orientation (the twinning plane of Fig. 1) is given, the twinned region arbitrarily bounded by <110> and <112> directions. The coupled shear is identical to that of Fig. 1. The "rotational" movement about coincidence sites generating the same twinned position could consist as shown of the translation a,/d% for each atom of a group of three in the B layer in a different one of the three <112> directions, and a similar translation of the underlying three atoms in the C layer in either the same or the opposite sense. This is not dissimilar to Kronberg and Wilson&apos;s construction for their 22" rotation of three adjacent (111) planes.

Jan 1, 1952

The volumes of Transactions, which are published annually, contain the list of officers, rules, etc., the Proceedings, and the papers revised for final publication. (In this revision, after the preliminary publication, authors are permitted to use the largest liberty; and the changes and additions made in papers are sometimes important. It should be borne in mind by those who study or quote a paper in the preliminary edition, that they may not have in that form the ultimate and deliberate expression of the author&apos;s views. It should be added, however, that in the majority of cases there are no important changes.) These volumes are for sale as follows, in paper covers:

Jan 1, 1917

Jan 1, 1923

By Z. Moser, W. Ptak

The experiments were carried out by the method of measuring the electromotive force of concentration cells having zinc as a reference electrode, the second electrode being the liquid alloy Zn-Sn-Cd-Pb. The electrolyte consisted of liquid chlorides and had zinc ions. The measurements were made for seventy -five alloys of different mole fractions within the temperature range of 714° to 877°K. The experimental results enabled the calculation of the activity of zinc in tested solutions. The activities of zinc were calculated by means of Krupkowski&apos;s formulas.3 In addition, the formulas for coefficients of activity of zinc, tin, cadmium. and lead as the function of composition and temperature were given. Activity of zinc was compared with the values obtained from experimental results, and good agreement has been observed. On this basis it can be stated that the theoretical formulas are suitable for determining the thermodynamic properties of liquid quaternary metal solutions. IN the metallurgical processes being carried out at present multicomponent liquid metal solutions take part. For the thermodynamic analysis of these processes it is necessary to know the thermodynamic properties of these solutions. Therefore, many experimental and theoretical papers deal with this problem. The theoretical papers are generally based on the assumption that the structure of liquid metals is similar to their structure in the solid state. In this manner the model of liquid solution, consequently described by means of statistical thermodynamics, has been accepted. This method is being lately developed, especially for solid solutions. Statistical thermodynamics was applied among others by Guggenheim 1 for describing the thermodynamic properties. Unfortunately, the formulas of statistical thermodynamics are often not suitable for the interpretation of experimental results. Attention should be drawn to the relations obtained by means of formulas of phenomenological thermodynamics which always have constants derived with the aid of experimental methods. In the case of the multi-component solutions which contain some additions of impurities besides the basic metal, wagner2 introduced interaction parameters. Equations for the relationship between the activity coefficients and composition were also given by Krupkowski." he application of these formulas requires a good knowledge of the thermodynamic properties of the corresponding binary systems. In these formulas, as in Wagner&apos;s, there appear constants which should be determined from ex- perimental data. Nowadays, different experimental methods are applied for evaluating the thermodynamic functions of solutions, for instance: vapor pressure measurements, calorimetric methods, and the measurements of electromotive force of concentration cells. In the present paper this last method for evaluating the thermodynamic properties of four-component systems, Zn-Sn-Cd-Pb, was applied. For instance in the case of Zn-Sn solutions Alabyshev and Landratov, 4 Fiorani and Valenti, 5 and ptak6 performed the investigations. The Zn-Pb system was worked out by Kleppa 7 and Cd-Pb and Cd-Sn by Elliot and chipman.&apos; This method was also applied for determining the activity of zinc in ternary solutions. 1) EXPERIMENTAL METHOD The experimental arrangement with detailed description is given in Fig. 1. It consists of resistance furnaces, one serving for melting samples and the other containing the flat-bottomed, measuring quartz tube with the liquid electrolyte. Liquid metals and alloys are in glass supremax tubes, which have an opening in their lower part above the metal level. This opening allows the filling of the tubes by the electrolyte. In these tubes tungsten wires are placed which by means of suitable conductors are connected with a potentiometer. It is assumed that tungsten dissolves Fig. 1—Schematic diagram of the experimental arrangement for the investigation of the thermodynamic properties of liquid metal solutions: 1, resistance furnaces; 2, autotransfor-mers; 3, galvanometers; 4, regulator of temperature; 5, gas purifier with concentrated H2SOP; 6, U-tube with P2O5; 7, thermostats; 8, steel block for thermostating; 9, supremax tubes for alloys; 10, tungsten electrodes; 11, inlet and outlet of argon; 12, measuring quartz tube; 13, tube for melting samples; 14, tube for thermocouple; 15, cover of quartz tube; 16, rubber seal; 17, bottom cover; 18, outlet of electrodes to potentiometer; 19, outlet of thermocouples to potentiometer; 20, upper view of the quartz tube cover; 21, orifices for cover screws; 22, orifice for argon inlet; 23, orifice for thermocouple; 24, orifices for tubes containing liquid metals; 25, inlet for water-cooling system.

Jan 1, 1969

By R. W. Armstrong, P. C. Jindal

WE should like to point out that Hu and cline.1 in their study of the recrystallization of titanium, have obtained data which appear very important for accurately determining the dependence of hardness on grain size for this material. It has been proposed2,3 that the macrohardness. H. of a poly crystalline material should depend on its average grain diameter, l. in accordance with the relationship: H =H0 + kHl-1/2 [1] where Ho and kH are experimental constants. This relationship follows from the hardness dependence on yield stress or flow stress4 and. thence. the Hall-Petch stress-grain size relations.5&apos;6 Fig. 1 shows the Diamond Pyramid Hardness. Dph. values vs the reciprocal square root of the average diameter of the recrystallized grains, taken from the titanium data reported by Hu and Cline. The data in this figure give a linear relationship for the hardness over a wider range of grain diameters than anyone has previously measured. The data are not linear, for example. on an I-1 or l-1/3 scale. At the very large grain sizes the data are in reasonable agreement with measurements earlier reported by Holden, Ogden, and Jaffee.7 For the grain sizes smaller than 1 µ, which correspond in Fig. 1 to hardness values greater than 150, the material was reported as not being completely recrystallized and, therefore, these data appear less meaningful as far as the hardness dependence on grain size is concerned. However. it has been suggested by other investigators that deformed materials exhibit strengthening due to an effective grain size refinement even in the unrecrys-tallized condition.8-10 Also. Hu and Cline have shown that a change in texture occurs for titanium during the recrystallization process and. especially. following it. The influence of this texture change on the hardness-grain size relation would be expected to be less than that reflected in the unidirectional stress-strain behavior, even for an hcp material. because of the actual combined stress system which applies for the hardness test. For, at least, certain combined stresses, average values of the orientation factors should still occur in the stress-grain size analysis of a material exhibiting a preferred orientation.&apos; We previously suggested3 that the experimental constants. H0 and kH. from the Meyer hardness-grain size relation should be correlated with the Hall-Petch constants, uoy and ky.5,6 Our recent study" of the Hall-Petch relation and the hardness-grain size results which obtain for a number of polycrystalline materials shows that: The inequality [2] is explained by noting that the hardness should be correlated. perhaps, with the flow stress at some value of strain, as suggested by Dugdale,12 and. also, that the influence of strain on the Hall-Petch relation is to increase uo and not change k very much." Normally. Dph values and Brinell hardness values are nearly equivalent to each other and to the Meyer hardness number. For the case of titanium, then. the inequality [2] may be evaluated using the experimental values of ao = 8.0 kg per sq mm and ky = 1.3 kg per mm3/2 obtained from the experiment of Guard.6,13 Thus, (Ho/uo) = 12 and (kH/k3) = 1.3. This research has been supported at the University of Maryland through the Center of Materials Research by the Advanced Research Projects Agency of the U.S. Government.

Jan 1, 1969

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who called at Institute headquarters during the period August 1, 1916 to September 10, 1916: C. L. Cantley, New Glasgow, N. S. H. M. La Follette, La Follette, Tenn. D. A. Cowell, Columbus, Ohio. Montrose L. Lee, Montevideo, Uruguay. Alexander Deussen, Houston, Texas. V. H. McNutt, Billings, Mont. Chas. E. Dutton, Goldfield, Nev. J. W. Maller, New York, N. Y. H. S. Emlaw, Grand Haven, Mich. Edwin W. Mills, Tul. Mi Chung, Chosen, J. M. Gillette, Swatsburg, N. Y. Korea. E. Gorilla, San Antonio, Texas. Francis R. Pine, Elizabeth N. J. Bertram Grant, Kingman, Arizona. Frank A. Ray, Columbus, Ohio. Ruger W. Hay, Bisbee, Arizona. John A. Rice, El Paso, Texas. C. F. Hendricks, Cobalt, Ontario. W. E. Rice, Ringwood Manor, N. J. Stanley C. Herold, San Jose, Cal. W. H. Staver, Lynchburg, Va. Lloyd Hoffman, Pottersville, N. J. Ralph H. Sweetser, Easton, Pa. Charles Hunter, London, England. Kirby Thomas, New York, N. Y. G. Jansen, Benkoelen, Sumatra. Henry Traphagen, Union Hill. T. H. Jenks, Oatman, Arizona. M. M. Valerius, Tulsa, Okla. Warren jenny, Chanaral, Chile. Wilfrid B. Wainewright, London, Eng. Walter A. Barrows, Jr., of Brainerd, Minn., has been elected president and general manager of the Thomas Iron Co., Easton, Pa., to succeed Ralph H. Sweetser, whose resignation of several months ago becomes

Jan 10, 1916

By Roger M. Nendick

The recovery of precious metals from heap leach solutions can be accomplished by two processes: 1. The Carbon Adsorption Process 2. The Merrill-Crowe Zinc Precipitation Process A brief review of the relative process economics is made. Each process presents certain design considerations that must be addressed during the evaluation and engineering design for the project. Discussion is presented on the design criteria for each process.

Jan 1, 1984

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Jan 1, 1938

By B. F. Tillson

There is a dearth of information on the economic threat of silicosis. Even the insurance companies and rating bureaus are in a quandary, and the majority of them avoid any action that will stir up an awakened public consciousness of the serious nature of this industrial hazard. Individual claims for $100,000 are now common in silicosis lawsuits. Because of (&apos;hidden costs," in lowered plant efficiency, the total cost of this disease to industry is probably four times its apparent direct cost. The direct costs vary with the labor policies of the employer and with the labor legislation in force. Direct costs may originate in three ways: (1) voluntary assumption by the employer of medical expenses and loss of earning power of stricken employees; (2) state enforcement of industrial disease compensation acts; and (3) awards or settlements after suits in common law. Examples are offered in the last two classifications. In the Rand, South Africa, compensation laws are in effect and in approximately 20 years prior to 1932 about $65,000,000 has been awarded for silicosis and an additional liability of $34,000,000 incurred, or an average of about t5,000,000 per year. During 1932 silicosis compensation on the Rand was about $6,000,000. No figures are available for the direct capital or operating costs for preventive measures there, nor for the additional "hidden costs." It might be reasonable to assume that silicosis has cost the gold-mining industry of South Africa twenty to twenty-five millions of dollars per year. It is estimated that common-law silicosis claims have, in the last few years, aggregated $50,000,000 in New York State alone and have exceeded $300,000,000 in the United States. Attention is called to the involved nature of the insurance situation for industrial diseases in contrast to accidents. The indeterminant, insidious nature of silicosis makes it particularly difficult to predict necessary insurance premiums and reserves. The serious hazard of this disease was not properly appreciated by either insurance companies or industrialists, so sufficient study has not been given its causation, prevention, detection, treatment, and compensation. Therefore legal difficul-

Jan 1, 1934

New Products Equipment

Jan 8, 1951

By D. Y. Geng, Syd S. Peng

This paper analyzes the effects of geology and mining methods on surface subsidence factor, angle of draw and angle of critical deformation based on the results of 40 longwall subsidence profiles in the Northern Appalachian coalfield. Several equations were derived to show the relationships between those parameters. Furthermore, the equations were transferred and plotted in the form of several monographs for convenience of applications.

Jan 1, 1982

By AIME AIME

THOUGH born in England-on Nov. 23, 1372 William Wraith was brought to this country at the age of ten. Eight years later he entered the University of Illinois, transferring to the Michigan College of Mines where he got his E.M. in 1894. For the next three years he was a mine surveyor for the fuel department of the Santa Fe Railroad. Then he got into the copper-mining industry, which has occupied his attention for the last forty years. First he was engineer, at Butte, for the Boston & Montana company, and then helped to build the Washoe smelter at Anaconda, of which he was assistant superintendent from 1906 to 1913. The Anaconda company then sent him to Salt Lake City as manager of its subsidiary.

Jan 1, 1938

[Trans. No. Place Date Vol. Page 1. Wilkes-Barre, Pa.* May, &apos;71.. 1 3 2. Bethlehem. Pa Aug., &apos;71.. 1 10 8. Troy, N. Y Nov., &apos;71.. 1 1S 4. Philadelphia, PaFeb., &apos;72.. 117 5. New York, N. Y.*May: &apos;78.. 120 5. Pittsburgh, PaOct., &apos;72.. 125 7. Boston, MassFeb., &apos;78.. 128 8. Philadelphia, Pa.* May, &apos;78.. 2 3 9. Easton, POct., &apos;78.. 27 10. New York. N. YFeb.. &apos;74.. 2 11]

Jan 1, 1946