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By Carl Davis

A description is given of grinding practice on the Rand and of experiments made to improve that practice. The paper includes a description of the experimental plants and methods and the results obtained. THE first tube-mill on the Rand was put into operation in May, 1904, at the Glen Deep Mine. From that time onwards, tube-mills were added to various plants, although little was known regarding the capacity of a given tube-mill when working on banket ore. Within a few years, however, the so-called standard size (length of shell 22 ft. 0 in. diameter 5 ft. 6 in.) was generally used until the last year or two. Practically the only exceptions were about 30 tube-mills having a length of 16 ft. and a diameter of 6 ft., and a few open-end mills of the roller-supported type. Most of the information obtained during the last 15 years has been obtained with mills of the standard dimensions. The adoption of the tube-mill as an accessory to the stamp mill was rapid; and where 3 tube-mills were working on the Rand at the end of 1904, 244 were in use seven years later.1 By 1910, good practice provided 1 tube-mill for 20 stamps of 2000-lb. falling weight. The horsepower of the motors driving the tube-mills had increased from. 80 to 100 and then to 125 at this date. Broadly speaking, current practice at that date aimed at a final product of which 60 per cent. was suitable for sand treatment and 40 per cent. for slime. The sand grading was +60 mesh, 6 per cent.; +90 mesh, 25 per cent.; -90 mesh, 69 per cent.; and the slime grading -200 mesh, 2 per cent.; -200 mesh, 98 per cent.

Jan 12, 1924

By Roy R. Jones, R. R. Sawyers

It has long been comnlon knowledge that workers in anthracite are prone to develop a disabling disease of the lungs. Some of the earliest scientific contributors dealing with anthracosis were: Pearson1, in his report in 1813, on the coloring matter of the bronchial glands and black spots in the lungs; Stratton2, in 1838, who first termed the condition anthracosis; Greenhow3, who reported to the pathological society in 1865, on the Black Lung of the Collier, and Pick4 in 1870, who reported on the chemical composition of the ash of a collier's lungs. Visconti5, in 1870, is accredited with being the first to use the term "silicosis" to denote the pathological condition of the lungs resulting from the inhalation of silica. Rovida6 confirmed the reports of Pick and Visconti in 1871, in his report on a case of silicosis and chemical examination of the lungs for silica content. The relationship of pulmonary infection, as associated with disabling pneumoconiosis affecting the coal miner, has frequently been discussed. While most reports have emphasized the role of infection, there has been some disagreement regarding the prevalence of tuberculosis among those suffering from anthracosis. The report by Wainwright and Nichols7 in 1905 has frequently been cited to show that the incidence of pulmonary tuberculosis among coal miners was less than that among the general population. It was their opinion that pulmonary tuberculosis was more prevalent among the miners' families than among the miners themselves. Collis and Gil-christ, in 1928 in their study of the Effects of Dust upon Coal Trimmers, concluded that among such workers there was an excess of deaths from bronchitis and pneumonia but not from pulmonary tuberculosis. They

Jan 1, 1936

By Roy R. Jones, R. R. Sawyers

It has long been comnlon knowledge that workers in anthracite are prone to develop a disabling disease of the lungs. Some of the earliest scientific contributors dealing with anthracosis were: Pearson1, in his report in 1813, on the coloring matter of the bronchial glands and black spots in the lungs; Stratton2, in 1838, who first termed the condition anthracosis; Greenhow3, who reported to the pathological society in 1865, on the Black Lung of the Collier, and Pick4 in 1870, who reported on the chemical composition of the ash of a collier's lungs. Visconti5, in 1870, is accredited with being the first to use the term "silicosis" to denote the pathological condition of the lungs resulting from the inhalation of silica. Rovida6 confirmed the reports of Pick and Visconti in 1871, in his report on a case of silicosis and chemical examination of the lungs for silica content. The relationship of pulmonary infection, as associated with disabling pneumoconiosis affecting the coal miner, has frequently been discussed. While most reports have emphasized the role of infection, there has been some disagreement regarding the prevalence of tuberculosis among those suffering from anthracosis. The report by Wainwright and Nichols7 in 1905 has frequently been cited to show that the incidence of pulmonary tuberculosis among coal miners was less than that among the general population. It was their opinion that pulmonary tuberculosis was more prevalent among the miners' families than among the miners themselves. Collis and Gil-christ, in 1928 in their study of the Effects of Dust upon Coal Trimmers, concluded that among such workers there was an excess of deaths from bronchitis and pneumonia but not from pulmonary tuberculosis. They

Jan 1, 1936

By G. R. Speich, R. A. Oriani

The rate of coarsening (Ostwald ripening) of copper precipitate Particles in an a-iron matrix has been studied in three Fe-Cu alloys containing 2.3, 4.0, and 5.4 wt pct Cu in the temperature range 730° to 830°C. The kinetics of Ostwald ripening ohevs the law as deduced by Lifshitz and Wagner so that matrix diffusion controls the process. The equilibrium shape of the particles is that of rods with hemispherical caps, and is due to the BOTH Lifshitz and slyozov and wagner3 have recently solved the complex problem of determining the rate of coarsening of an assembly of precipitate particles. Both workers, although using somewhat different mathematical approaches, arrive at the same equation for the relation between the mean radius 7 of a distribution of spherical particles and the bulk solubility co, diffusivity D in the matrix, large anisotropy in the copper/a iron interfacial free energy (y,/y, = 4). A Lifshitz -Wagner equation, modified for both the nonsphericity of the diffusion field and the reformulation of the Gibbs-Thomson equation for the case of nonsphencal particles, is derived. Using the modified equation, the calculated values of the mean radius are smaller than those observed by a factor of about one -half. absolute temperature T, gas constant R, surface free energy y of the precipitate/matrix interface, and the time t of aging: where V, is the molar volume of the precipitate and v is a stoichiometric factor. Wagner's treatment is restricted to the case of spherical particles growing in a liquid matrix where strain energy is not a factor. Lifshitz and slyozov have discussed the effect of anisotropic particle shapes and internal strains on the rate of coarsening. Oriani4

Jan 1, 1965

By W. E. Bruce, R. J. Morrell, James Paone

This chapter is a partial summary of an investigation by the U.S. Bureau of Mines (USBM) made in response to a recent request by the Assistant Secretary, Water and Power Development of the U.S. Department of the Interior, for a comprehensive review of horizontal boring technology related to underground power-line installation. This review is concerned primarily with 3 to 36-in. diam horizontal holes from several hundred to several thousand feet in length. An electric power system consists of three essential functions: generation, transmission, and distribution. The generation component includes the generating station and step-up substation; the transmission component includes the transmission line and stepdown substation at typical voltage levels ranging from 69 to 345 kv for underground lines and 69 to 500 kv for overhead transmission lines; the distribution component includes the distribution line carrying the commonly used voltages of 120, 208, and 240 v, the distribution transformer, and the line to the service customer.l The Federal Power Commission reports that 1600 miles of underground transmission lines of 60 to 345-kv capacity are now in service in the United States. By 1980, it is estimated that approximately 3000 miles of trans- mission lines will have to be placed underground.2 The cost of burying electric transmission lines underground in metropolitan areas, approximately 30 miles from the center of each of the most populated cities, will exceed $1.5 billion with the methods now available. The wide spread in unit costs of overhead and underground transmission lines narrows as right-of-way costs for overhead transmission in congested areas increase. Improved methods of underground emplacement will certainly reduce this difference in costs and even further favor underground emplacement. Also, in the future, overhead transmission lines will probably not be permitted in highly built-up areas.

Jan 1, 1970

By Courtenay DeKalb

Revision of the United States mining law is needed chiefly because of the following reasons: 1. The conceptions as to the characteristics of orebodies that were held at the time the statute of 1872 was enacted have since proved to be in many respects erroneous. 2. The operation of the existing law has been found to work unnecessary hardship upon many claimants to mineral land. 3. The existing statute fails in large degree to encourage development of mineral resources. 4. The existing law often produces conflict between placer and lode-claim rights, working unnecessary injustice to placer claimants. 5. The methods of establishing the rights of locators on United States mineral land are defective, and are not uniform throughout the States within which such lands exist. Law of the Apex The objections to the so-called "law of the apex" are so well known as to require no detailed statement. It is sufficient to point out that the apex rule was based upon the notion that ore deposits consisted of well-formed veins included between definite walls, like the slice of ham in a sandwich. The fact is that veins conforming to that simple type are rare. Irregularity is the rule, and the chief metal production of the United States comes from mass? which bear no resemblance to the tabular form of vein. Manifestly the law of the apex fails completely in such cases. Moreover, the tendency is constantly toward the exploitation of ores of lower grade than could formerly be worked, and such deposits exist mainly in the form of large irregular impregnated zones and masses, so that the future development of our mineral resources would be continuously embarrassed by shadowy claims to extra-lateral rights by the locators of so-called apexes.

Jan 1, 1915

By Lewis H. Reiland

IN 1920, for the first time, the U. S. Geological Survey employed aerial photography in constructing planimetric maps. Contours were added by aerial photography and cultural details corrected. From 1925 to 1929 photogrammetric plotting machines and instruments of foreign design appeared in America for use in constructing complete topographic maps. During this period the only American technique developed was the Brock process, carried out with great success by Aero Service Corp. of Philadelphia, a pioneer in the field of photogrammetry. Between the first and second world wars the Multiplex projector, the Aerocartigraph, and the Stereoplanigraph appeared. The Multiplex projector, most popular of the three, determines three-dimensional values with very high accuracy. Many refinements have been added year by year, and it is now possible to photograph vast areas in a very short time and produce planimetric, topographic, and geologic maps of great value at very low cost per acre as compared with all methods previously known and in use. Both on the ground and in the air, however, accurate results can be produced only with highly skilled personnel and costly scientific instruments and machines. As early as 1928 the writer collected from the U. S. Army Engineers all available formulas and data on photogrammetry and personally contracted a local project of 2800 acres to be surveyed from the air. From the 10,000-ft altitude required for scale the cameras, each equipped with 4-K filters, pierced a ground haze of about 5000 ft, achieving clear, de- finable photography. The result was so gratifying, and the continuing progress in this method of surveying and mapping so great, that in the matter of economy it can hardly be surpassed. Pocahontas Land Corp., for example, constantly refers to its complete file of aero prints, covering its entire ownership in West Virginia, Virginia, and Kentucky. Photostats are enlarged or reduced from these prints to match the scale of company maps, to which various features are then added.

Jan 7, 1957

By Frederic E. Carter

There have been many attempts to prove that platinum was known to the ancients, but since no traces of the metal have been found in the relics of early times, it must be concluded that it was not known to them. As far as records go, it was actually first discovered in the 16th century in a Spanish mine on the Pinto River in South America; from which source it received its name of Platina del Pinto (little silver from the Pinto). It was more or less of a rarity and was a subject of interest to a few chemists only, until the year 1822 when the metal was first discovered in Russia. In 1819 there were noticed in the washings of the gold sands of the southern part of the Ural Mountains, grains of a heavy white substance, but it was not until three years later that this substance was found to contain platinum. While at first the amounts of platinum brought from the Urals were meager, prospecting soon disclosed rich deposits extending over a considerable area, and nuggets from 10 to 20 lb. were by no means rare. This discovery assured to chemists an ample supply of platinum for their crucibles, etc. The ore is now found in various parts of the world but the richest deposits are still found in the Ural Mountains. The platinum of commerce is obtained entirely from alluvial deposits at depths varying from 6 to 40 ft. The sand and gravel of former river beds are subjected to a series of screenings and washings to effect the separation of the ore. Actually, probably all gold-bearing gravel beds of the world contain platinum, and it is more than likely that large quantities of platinum ore have been thrown away with the black sand washings from gold placer deposits. This is especially true of the alluvial deposits of the Pacific Coast in California and Oregon. Platinum ore is usually found in the form of rounded or flattened grains of "sand," and occasionally in irregular lumps of the size of peas. Large nuggets are very rare. The ore has a metallic luster and is distinguished by its steel gray color, but shows light gray streak when rubbed on a hard white surface; it has a high specific gravity, 16 to 19; is infusible in the hottest blast furnaces, and insoluble in any single acid. Platinum ore is a complex body consisting of the metal in combination with varying proportions of the other members of the platinum group; iridium,

By Frederick Clapp

ALTHOUGH many oil fields have been, and still are being, discovered in Oklahoma, the geology and structure of most of them have not become familiar to the general public because of the delay in securing government geological surveys and the reluctance of oil companies and other interested parties to give out their "inside information." Therefore, until official surveys are available, it behooves us to publish geological results as soon as possible. Fortunately the writer has been authorized by the Cement Field Oil Co. to publish his data on the Cement field, Caddo County at this time. LOCALITY AND DESCRIPTION The Cement field is situated in the part of Oklahoma known generally, until recently, as "Healdton fields," and lies 60 mi. (96 km.) northwest of the Healdton field proper. Like the Healdton field, it forms an approximate ellipse, trending northwest and southeast through the village of Cement on the St. Louis-San Francisco Railroad, on which it is reached in 2 ½ hours from Oklahoma City. In its geological structure, the field constitutes an anticline over 13 mi. (21 km.) long and from 1 to 3 mi. wide; the point of greatest width being not far from its intersection by the above-named railroad. The major axis trends north 75° west from the village of Cement; but eastward appears deflected (if field interpretations are correct) to about south. 45° east. About 5 mi. south lies an approximately parallel syncline, which may be conveniently called the Cyril syncline, the south and west boundaries of which may be distant many miles, but forming a closed basin', south of the Cement anticline. The position of the offsetting synclinal axis, which is believed to lie north and east of Cement, has not been discovered.

Jan 2, 1920

By Caner Zanbak

Deformational behavior of a rock mass can be modeled with a constitutive law based on theories of elasticity, and plastic and viscous deformation. For most rock types, such constitutive models may be used with confidence because there is no geochemical interaction between the rock-forming minerals and water. However, if volume changes in the rock due to geochemical phase transitions are predicted, then these volume changes must be converted into mechanical parameters and must be included into the constitutive laws. In this paper, geochemical phase transitions between anhydrite (CaS04) and gypsum (CaS04-2H20) will be brought to the attention of researchers in rock mechanics. Hydration of anhydrite to gypsum may yield volume increases up to 62.6 percent and dehydration of gypsum to anhydrite may cause volume decreases up to 38.5 percent. If one were to convert the volume increases in hydrating anhydrite into strains and calculates the required stresses to restrict the expansions, the magnitude of stresses will be found at GPa levels. Such stresses on swelling anhydrite layers cannot be provided by geologic media. Therefore, the host rocks will deform under these high stresses. On the other hand, under increasing stresses, geochemical transition of anhydrite to gypsum may stop after some hydration of anhydrite, and anhydrite and gypsum systems may become stable. Changes in temperature and solution compositions in the anhydritel gypsum system also control the stability of the geochemical system, and therefore, the extent of volume changes. A similar conceptual model can be drawn for volume decreases due to dehydration of gypsum to anhydrite. In this case, stress reduction on the gypsum layer may cause extensive fracturing and changes in the state of stress in the host rock mass.

Jan 1, 1984

The Library of the above-named Societies is open from 9 A.M. to 10 P.M. on all week-days, except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information as to the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received. may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute can be of service to the Library by forwarding copies of mining reports, maps privately issued, and similar material, which will be classified, indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will be welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them.

Jan 3, 1915

By Milnor Roberts

The Nicola Valley coal-field is small, but it seems likely to become important because of its commanding position in a rich region that is developing rapidly. Bituminous coking-coal in workable quantity has not been found at any other point between the Crow's Nest Pass region, about 400 miles to the east, and Vancouver island, 250 miles westward. The Canadian Pacific railway reached the Nicola valley two years ago ; two other lines, the Canadian Northern and the Great Northern, are building towards the valley. The vast region between the Rocky mountains and the Pacific coast, extending northward for several hundred miles from the international boundary, which has been the scene of extensive mining- and smelting-operations for many years, is filling up with settlers, who are attracted by the wealth of minerals and timber, the rich soil of the valleys, and the fine climate. The Nicola river, flowing westward through the valley of that name in the Yale district, discharges into the Thompson river, which is the eastern branch of the Fraser. The transcontinental line of the Canadian Pacific railway crosses the mouth of the Nicola river at Spence's bridge, 178 miles from Vancouver. From Spence's bridge the Nicola branch line ascends the valley for 40 miles to Merritt, the coal-center, and continues 7 miles farther to the town of Nicola. Thus the haul from the mines at an elevatioiz of 2,000 ft. to salt water is 218 miles down river-grades. The Nicola branch will be continued about 150 miles farther eastward to Penticton, where it will connect with an extension of the line through the rich Kootenay and Boundary districts. The Canadian government has granted a subsidy of $6,000 per mile, to which the provincial government is planning to add $5,000 per mile, to assist in the construction of the Nicola extension. Upon the

Jan 1, 1910

By William C. Brice

Minnesota is involved in planning controversies related to taconite and potential copper-nickel mining. Mine facility planning includes the Reserve dining on-land tailings disposal issue and the potential for a new copper-nickel mining district. Both provide a unique opportunity for innovative planning in the attempt to be responsive to public and private interests. Concerns that emanate as a result of mineral resource activities include environmental protection, land use competition, land exchanges, highway and utility extensions, and legal constraints on public or private lands. The purpose of this newly-developed planning approach is to anticipate such issues and provide a rational information base for dealing with them. The result will be a framework plan for guiding public planning, and an impact assessment for reviewing the implications of industrial project proposals. The approach uses a computer-stored resource inventory of natural and cultural information. Geographic data is mapped and entered into a computer storage and retrieval system. This enables systematic analysis of mineral resources along with environmental and land use considerations. Computer mapping describes the relationship of each activity and allows identification of potential conflicts; it also shows geographical extent in the form of statistical compilations. Resource data is being collected and compiled using a standard metric grid (Universal Transverse Mercator). Individual cells are 100 m. squares and represent areas of about 2.5 acres. The study area contains about 145,000 cells. Data inventories are being compiled in 25 natural and cultural resource categories. Geologic variables include Bedrock Geology, Taconite Reserves and Potential Resources, Depth to the Duluth Complex Contact and two soil inventories. Topographic and hydrologic variables include elevation, slope, slope orientation, surface hydrology, and watersheds. There are also 6 biological data variables and 7 land use inventories.

Jan 1, 1977

By J. A. Brusset

THE Adanac mine was opened by West Canadian Collieries, Ltd. in 1943, and the question soon arose as to which system of haulage should be selected. Compressed-air locomotives and ropes were rejected on the ground of high cost. Since under the Alberta Mines Act the use of trolley locomotives underground in coal seams is not permitted, the choice lay between storage battery and Diesel locomotives, The preference of the author, who had experience with both in gassy French coal mines prior to 1930, was for Diesel locomotives due to lower cost of installation and greater flexibility and reliability. It was realized that the adoption of Diesels would be somewhat of an innovation since in the United States the mining laws prohibit their use under- ground in coal mines, and in Great Britain in 1943 their use was only in the incipient stage. By 1945, 25 Diesel locomotives were in use underground in gassy mines in Great Britain, and approval had been granted for the use of an additional fifty of two approved types also for gassy mines. Numerous special regulations of the British Coal Mines Act have been formulated to govern the use of Diesel locomotives. For instance, they are not allowed closer than 200 yards from the working face; daily inspections are required; and a weekly checkup and cleaning must be given the engine by a competent engineer. Also, methane content of the air in the roadway can never exceed 1.25 percent, and daily checks must be made if it exceeds 0.75 percent. Under Alberta regulations, we were required to use a flameproof type engine, to be used only in fresh air intake. The engine fumes had to travel along a separate ventilation split where no man was permanently employed. It is forbidden to run a

Jan 1, 1949

By Fred J. Hurst

In 1934, Irvin Lavine (A), University of North Dakota, stated that the low-rank coals (lignite and subbituminous) of this country represent a vast tonnage of fuel of commercial value and predicted that some day they will play an important role in our economic welfare. Lavine also pointed out that one of the major problems with efficient utilization of the low-rank coals is their high moisture content. Following the discovery of uranium-bearing lignite in the Williston basin of North and South Dakota in 1948 by D. G. Wyant and E. P. Beroni, detailed investigations were conducted (primarily during 1950 to 1954) by members of the U. S. Geological Survey to evaluate the geologic factors and economic possibilities of the radioactive lignites as a source of uranium. The information gained in these studies and summarized in several papers indicated that a large potential reserve of uranium is contained in the subbituminous coal and lignite deposits of the Dakotas and Wyoming (2,3,4). Most investigators concluded that an epigenetic emplacement of uranium in the coal by means of circulating groundwater and the more extensive concentrations of uranium in coal are apparently related to the permeability of the rocks enclosing the coal beds. Breger (5) and others have shown that uranium is readily adsorbed by coal and is held irreversibly as a disseminated adsorbed constituent. Briefly, lignite beds containing 0.1 to 10% uranium have been discovered in the Dakotas and Wyoming. The distribution of uranium was found to be erratic and was usually concentrated in thin layers, which were characteristically 10 to 14 in. thick and occasionally 30 to 36 in. thick. Lignite beds more than 3 ft. thick generally contain more uranium at the top of the bed than at the bottom. Special strip mining techniques are required to mine these thin

Jan 1, 1983

By Samuel G. Lasky

FAULTING at Kennecott, with its attendant fracturing, is unusual, complex, and important. As study and knowledge of the various fault systems have progressed, appreciation of that importance has helped in the selection of proper horizons for exploration and in the avoidance of useless crosscutting and drifting. During the study of this faulting and fracturing, a suggestion concerning the formation of the ore-bearing fissures occurred to me. Further study in the available portions of the approximately 45 miles of workings in the Kennecott mines for the purpose of checking up the the suggestion led to the hypothesis which this paper will attempt to present. Briefly, the hypothesis may be stated as follows: The formation of transverse faults that stop against a main system is connected with changes in the strike or dip of the main fault, and such cross faults or fractures lie in the moving block of the main fault system and indicate a change in strike or dip of the main fault. It has been found that each kind of change tends to produce definite effects and that careful study of the evidence can often suggest the exact type of change. Outline of Kennecott Mines Geology The mines at Kennecott are on the northeast flank of a broad anticlinell where erosion has exposed the Upper Triassic Chitistone limestone resting conformably on the Permian or Triassic Nikolai greenstone.2 These two are the only formations exposed in the immediate vicinity of the mines that bear relation to the ore deposits. The Nikolai greenstone is a series of altered basaltic lava flows, the actual thickness of which is unknown. The Chitistone limestone is the ore-bearing formation. At its base is a bed of about 5 ft. of red, green, or black shale which shows strong evidence of movement wherever it is exposed underground—one of the

Jan 1, 1929

By H. H. Stoek

THE fundamental reasons underlying the choice of a method of mining a coal seam are safety of operation, cheapness of producing the product and the character of the product as a saleable article. From the standpoint of safety, open or strip coal mining is always preferable, as many of the dangers inherent to underground work are absent, such as explosions of gas and dust, falls of roof and coal, and also to a great extent those due to haulage and the use of explosives, thus eliminating three of the chief causes of accident from which about 75 per cent. of the underground accidents in coal mines occur. The conditions under which coal is stripped also make the work much safer than ordinary quarry work, as the depth. of the pit is usually comparatively slight. From the standpoint of low mining cost, there is much misapprehension and many of the costs given are misleading in that they do not take into account such items as the destruction of the surface for future use, the full cost of the removal of the overburden, depreciation, amortization, coal depletion, loss of time through floods and from bad weather in winter, etc. Coal is no doubt often put on the cars at less cost by stripping than by underground mining, but by no means always so, as is too generally assumed. In some cases coal must be obtained by stripping or not at all, due to the small amount of overburden that renders underground mining impossible.

Jan 9, 1917

By C. F. Quest, T. S. Washburn

The steel industry has a definite need in its tonnage mills for a formula relating expected tensile strength to the analysis of the steel. The McWilliam-Barnes1 and other less comprehensive formulas are used for this purpose, but these formulas were designed for an analysis range that does not include the medium manganese and silicon-bearing steels. This type of steel is being produced to meet the demand for tensile strength slightly higher than that of ordinary structural steel but not high enough to justify expensive alloy steels. The purpose of this paper is to present a somewhat more comprehensive formula based on data accumulated over a number of years by the Inland Steel Co., and to discuss the method followed in obtaining a formula to fit the data. The resultant formula admittedly is still weak in some respects, but for the expanded analysis range appears to be an improvement over the other formulas. It is hoped that with the collection of more data and possible collaboration with other mills studying this problem it will be possible to work out a more nearly perfect formula. Several publications have been issued on this subject. In some, the equation type of relation was evolved while others made a combination of tables and an equation. The latter include work by Campbel12,3 and Webster.4,5 Campbell classified the steels as acid and basic and applied a different formula to each. For basic steels, he used the equation: Teosile etrength = 41500 + 770C + 1000P + yMn [1 y was a variable depending on the carbon and manganese content of the steel and was listed in tables. Webster investigated acid Bessemer steel and developed the equation: Tensile strength = 38000 + 800C + xTP+ yMn [2]

Jan 1, 1940

By C. F. Quest, T. S. Washburn

The steel industry has a definite need in its tonnage mills for a formula relating expected tensile strength to the analysis of the steel. The McWilliam-Barnes1 and other less comprehensive formulas are used for this purpose, but these formulas were designed for an analysis range that does not include the medium manganese and silicon-bearing steels. This type of steel is being produced to meet the demand for tensile strength slightly higher than that of ordinary structural steel but not high enough to justify expensive alloy steels. The purpose of this paper is to present a somewhat more comprehensive formula based on data accumulated over a number of years by the Inland Steel Co., and to discuss the method followed in obtaining a formula to fit the data. The resultant formula admittedly is still weak in some respects, but for the expanded analysis range appears to be an improvement over the other formulas. It is hoped that with the collection of more data and possible collaboration with other mills studying this problem it will be possible to work out a more nearly perfect formula. Several publications have been issued on this subject. In some, the equation type of relation was evolved while others made a combination of tables and an equation. The latter include work by Campbel12,3 and Webster.4,5 Campbell classified the steels as acid and basic and applied a different formula to each. For basic steels, he used the equation: Teosile etrength = 41500 + 770C + 1000P + yMn [1 y was a variable depending on the carbon and manganese content of the steel and was listed in tables. Webster investigated acid Bessemer steel and developed the equation: Tensile strength = 38000 + 800C + xTP+ yMn [2]

Jan 1, 1940

By D. J. Varnes

Rocks in mines, quarries, and many outcrops commonly show evidence of being under high stress. Saw cuts and drillholes close in, partly mined coal bursts violently, and pillars crush and rock spalls in mines even at moderate depths. Similarly, strong and massive rocks such as granite and sandstone naturally divide themselves into sheets that lie more or less parallel to their outward topographic form. The sheets may be either convex or concave. Thin plates of bare rock surfaces bow up and buckle. Such effects often cannot be explained by the obvious loads now acting on the rock, that is, by loads resulting from overburden, topographic irregularities, or stress concentration around openings. The stresses exceed those that would result from such loads. Two interpretations of such excess stresses have been made. In one, the stresses are assigned in origin to now active tectonic forces. In the other, they are regarded as leftover and locked in from some previous state at which higher pressures prevailed. These two sources may both operate and they generally cannot be distinguished easily in the field. There are other complicating sources of stress such as temperature gradients and chemical alteration. Nevertheless, some bodies of rock, by exfoliating, show evidence of high internal stress even though they are practically unweathered and so isolated topographically that the presence in them of significant stress due to exterior loads or active tectonic forces seems unlikely (Fig. 1). Moreover, completely isolated rocks are known to change density, shape, or size 1,2 to expand under constant compressive stress;3 and even to disintegrate 4,5 without the intervention of weathering processes. The stresses involved here must be truly residual in the sense long used by metallurgists; that is, residual stresses in a body are those that remain.

Jan 1, 1970