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By A. Todd Davis

"Introduction“CAN YQUR Company afford not to train?"" This question was asked by Jack Taylor in the Factory Management Magazine for June, 1950. Mr. Taylor went on to say, ""No, it can't; no Company can"". It's true that many training programmes have not done the job they were designed to do because of a number of factors such as parts of management resenting training, management failing to understand the abstract values of training, and management giving impossible assignments or picking the wrong trainers. However, Mr. Taylor summarizes his article by saying that a properly-designed and •conducted training programme brings a company or a corporation to the point where the question is: ""Can my Company afford not to train?""About two years ago, in July, 1952, Nevada Mines Division of the Kennecott Copper Corporation embarked on a training programme, the same type of programme that had been inaugurated earlier at the •Utah Copper Division at Bingham, Magna, and Garfield, Utah. President Charles Cox of Kennecott, in •a speech made •before the Utah Bankers Association in June of 1951, stated that, ""I think that our programme of employee training is one of the most important phases of our entire operation"". That statement might be said to be one of the guiding principles of training at Nevada Mines Division. Training is supported by top managements and down the line to Division managements. As the years go by, the Company expects to receive many benefits from training."

Jan 1, 1954

By A. McMullen

"IntroductionTHE LOW-VOLATILE bituminous coals of the Brazeau field, Nordegg, Alberta, are soft and weak in structure. The seams contain .bands of inferior material, locally designated 'black jack', and thin bands of friable carbonaceous shale having no definite horizon but usually 'floating' in the seam. Because of the weakness• of the coal and the friable nature of the shale bands, run-of-mine coal usually contains a very high percentage of fines, as •Shown in the following table:SIZE WEIGHT. %Plus 1/2 in 25.61/2 – 1/4 in 13.31/4 - 1/8 in 14.6Minus 1/8 in 46.5The most convenient way of cleaning the fine coal would be by treating it in association with the coarse coal, so that no additional plant would be necessary. To a limited extent this is possible in certain types of equipment, notably the jig. A system of washing without pre-sizing is not •attractive, however, when dealing with the friable coal under consideration, which contains •a preponderant proportion of fines. At the new Brazeau washery, separation is made at 3/8-inch on •a Robins 'Vibrex' •screen, the coarse sizes being cleaned in •a standard pulsator-type jig. A feldspar jig is used to clean the minus 3/8-inch fraction."

Jan 1, 1954

By Jas. E. Thomson

"The Omega mine is in McVittie township in the Larder Lake area, Ontario. Production at the mine commenced in 1936, and, until the end of 1946, ore milled amounted to 1,558,604 tons, from which 207,074 oz. gold and 28,205 oz. silver, valued at $7,585,470, were recovered. The mine workings extend to a depth of 1,975 feet.GEOLOGYThe geology of the mine has been described in detail by C. P. Jenney (l) and the writer (2). The general geology and structure in the vicinity of the mine is discussed on an earlier page in this volume. The rock formations found in the mine workings are indicated on the accompanying plan and section (Figs. 1and2). They consist of an intermingled, south dipping complex of volcanics, sediments, and secondary talc-chlorite schists and carbonates. The carbonatized rocks, which are often referred to as 'dolomite' in the Larder Lake camp, are siliceous-carbonate replacements in the talc-chlorite schist zones. In places they contain green mica, probably fuchsite, and are cut by a stockwork of quartz veinlets and stringers. A stock of syenitic intrusives lies south of the mine workings.STRUCTUREThe main structural features are indicated in Figs. 1 and 2. The formations and orebodies have a pronounced southerly dip, which flattens with depth. The talc-chlorite schist and 'dolomite' zones are part of the Larder Lake fault or 'break' on which there appears to be very large displacement. Evidence throughout the district would indicate that the south side moved up and, in the case of the Omega mine, the thrust may have been distributed throughout the several intensely sheared zones. This slice faulting could account for the repetition of sediments and volcanics. An alternative possibility would be original interbedding of volcanics and sediments."

Jan 1, 1954

By Alexander Smith

"The three principal known mineral deposits of the Taku River area lie in the Tulsequah synclinorium. The axis of this north-south trending structure is along Tulsequah River valley; about 6 miles east of the eastern contact of the Coast Range batholith.The one proven mine of the area, the Polaris-Taku, is on the west side of the valley. It is a gold property, the gold occurring in fine needles of arsenopyrite disseminated in carbonatized volcanics. The mine was originally called the Whitewater, and the adjacent area the Whitewater gold belt. During the years 1937 to 1942 gold having a value of $3,284,000 was produced from 313,500 tons of ore milled."

Jan 1, 1954

By Cleo G. Rall

The method for determining the effective porosity of oil- and gas-bearing sands described in this report is a development of earlier methods (28)3/ devised by the Bureau of Mines. The apparatus bas been improved and made more convenient to use, but the procedure is essentially the same as that which has been in use for maw years. A tabulation at the end of the report gives the results of more than 4,800 porosity determinations for oil sands4/ in the fields of 13 States, A selected bibliography of references to articles containing descriptions and evaluations of various methods of' determining porosity is included in this report. The method was devised and developed at the Petroleum Experiment Station at Bartlesville, Okla., as part of the Bureau's research on fluid-energy relationships and on methods of improving the recovery of crude oil from underground reservoirs.

Jan 1, 1954

By C. K. Rose

A hydraulic scaling rig was placed in operation at the Bureau of Mines oil-shale mine near Rifle, Colo., in 1953. The rig consists of a self-leveling platform mounted on a hydraulic-powered boom. The boom is mounted on the bed of a diesel truck. The equipment provides a movable work platform from which two men can work in safety and comfort while barring loose rock from the backs and walls of the rooms, pillars, and haulageways. INTRODUCTION As a part of its synthetic liquid fuels program the Bureau of Mines has developed a mine in the richer oil-shale beds of the Green River formation near Rifle, Colo. An important part of the work of the Oil-Shale Mining Branch is investigation of techniques for low-cost mining of oil shale on a commercial basis. It is evident that scaling loose rock from the high backs and walls of the mine represents a portion of the direct mining cost. This paper describes the development of a scaling rig for operation in the upper heading of the mine, which is 39 feet high.

Jan 1, 1954

By Roberto Antoniolli

"IntroductionSINCE ancient times, the precious metals have played an important role in influencing the course of history. Silver and gold happened to occur, although in small amounts, in those countries where the early civilizations developed. Their persistent brightness certainly amazed the primitive people, who also found it easy to shape them into ornaments •and implements. Ever since then their properties have made them seem desirable possessions.Use of precious metals as money was the natural consequence of man's desire for them. The possibility of changing an ornament into a tool or food at any time, and the ease with which such medium of exchange could be carried and hidden, further increased the demand for the two metals.Silver was probably discovered after gold and copper, and was undoubtedly found by prehistoric man as native silver. The oldest silver articles have been discovered in Chaldean tombs and date back to 5000 B.C. The earliest ascertained producers of silver were Asia Minor and the Iberian Peninsula. The Romans worked deposits in Spain, Britain, and France. In the Middle Ages, some silver was extracted from German deposits, and near the end of the Middle Ages systematic workings were carried on at Freiberg, Schneeberg, and Joachimsthal (1).Before the discovery of the New Continent, the Aztecs and Toltecs in Mexico, and the Incas in Peru, had made extensive use of silver. In the 16th century the Mexican deposits became the largest source of the world silver."

Jan 1, 1954

By J. S. Kasper, R. M. Waterstrat, B. F. Decker

THE existence of v phase in the Mn-Mo system was discovered in this laboratory several years ago,' but neither the conditions of its formation nor its composition were known, and preliminary attempts to reproduce the phase were unsuccessful. We wish now to specify the information appropriate to phase formation on the basis of experiments performed since that time. The starting materials were in every case electrolytic manganese and high purity molybdenum. Two methods of preparation were employed: l—arc-melting varying combinations of the elements in an inert atmosphere and subsequent heat treating, and 2—sintering compressed mixtures of finely divided powders of the elements. In the latter method, the powders were first passed through 200 mesh screen and then compressed into cylinders of % in. diameter and % in. length, which were sintered at elevated temperatures in an atmosphere of dry hydrogen. For some samples, the sintering temperature was 1200°C (for 1 hr), and these were then heat- treated at lower temperatures for times up to 24 hr. Eventually it was found, for the proper composition, that essentially pure a phase could be produced by sintering at 1125°C for 3 hr. Quenching to room temperature was effected by means of a stream of cold, dry hydrogen in a water-cooled chamber. The arc-melting procedure was found to be unsatisfactory after an investigation of many samples at different compositions and temperatures. Large quantities of manganese were vaporized during melting and none of the products were homogeneous or contained extended regions of pure phase. Nonetheless, these experiments established that no formation occurs in the Mn-Mo system below 1115oC, and indicated, at least roughly, the composition range of interest for further exploration. The more definite results obtained from samples produced by the second method are given in Table I. A portion of sample 2 heated for 16 hr at 1000°C in a Vycor tube transformed to molybdenum plus unidentified phases of complex X-ray pattern. From these few results it appears that the region of phase is quite narrow in composition. It is of interest that the composition is such as to make for difficulties in correlating this structure on an electron atom basis with other a structures of iron, cobalt, and nickel. In that respect Mn-Mo shows the same anomaly as Mn-Cr and Mn-V systems.' A second feature is that in common with the two other known molybdenum (Fe-Mo and Co-Mo), Mn-Mo v exists only at elevated temperatures. The X-ray powder pattern of the pure a phase of Mn-Mo is given in Table 11. It agrees well with the patterns established for other structures, especially with that for Fe-Mo as given by Goldschmidt.An attempt is being made to establish whether an ordering of the respective atoms occurs and such information will be reported in a future publication. Acknowledgment The authors acknowledge gratefully the assistance of Mrs. J. R. Belanger in some portions of this work. References 'J. S. Kasper, B. F. Decker, and J. R. Belanger: Journal of Applied Physics (1951) 22, p. 361. 2 A. H. Sully: Journal Inst. Metals (1951) 80, p. 173. H. J. Goldschmidt: Research (1949) 2, p. 343.

Jan 1, 1954

By W. T. Turrall, M. J. Cook

A discussion of modern developments in beneficiation of fine sizes of anthracite, this paper includes a description of the plant flowsheet, an analysis of operating results, and a summary of fundamentals of mineral separation relative to plant operation. DURING the past several years Lehigh Naviga-tion Coal Co. has installed equipment at Tamaqua and Lansford collieries for cleaning and sizing No. 4 buckwheat —3/32 + 3/64 in. and for recovering and cleaning flotation coal —20 + 200 mesh at Tamaqua colliery. Papers describing some of these installations have been presented to AIME. At Coaldale colliery, however, methods used to clean fine coal were inadequate and inefficient. Management decided upon a thorough investigation of all existing processes before building a plant to treat the combined three sizes mentioned. Investigation, carried out on company property and at other plants, entailed a study of hydrotators, hydroclassifiers, tables, spirals, flotation machines, methods of screening, and methods of dewatering. On the basis of this investigation a flowsheet was designed which necessarily excluded many processes in use, and the writers wish to emphasize that no criticism is implied by omission of processes or machines. A determining factor in selection of many machines was the policy of standardizing equipment wherever possible. Flowsheet and Operational Data The first principle to be considered in designing of any plant is efficiency of cleaning as related to laws of classification. Beneficiation of coal may be described as separation of two materials having different specific gravities. Although there is an inherent ash content even in the purest coal which slightly affects its specific gravity, it is recognized that many particles are true middlings. The percentage of these particles allowable in the final product depends upon the ultimate ash, or specifications of the consumer. Richards in his study of free settling and hindered settling classification' determined that particles of equal size and different specific gravities had unequal settling velocities. He also determined a definite size relationship for equal settling velocities with free settling and hindered settling conditions. Considering the design of machines used to clean No. 4 and No. 5 buckwheat, it may be assumed that both free settling and hindered settling conditions exist and that ratio of size for practical operations is between the established values. The essential factor is that the more efficiently and closely sized the feed is maintained, the more nearly perfect the resulting separation. Flowsheet design was governed primarily by factors related to the 1200 to 1500 tons per hr feed to the main plant. It should be stressed that because of the many sources of supply from mine and stripping, the physical characteristics of this feed varied considerably. The most significant influence was varying percentage of fines, necessitating that all machines be capable of operating under maximum peak load during periods of surge. Since cleaning practice is a wet process, about 9000 gal per min containing 14 to 15 pct solids, or 350 tons per hr, must be treated. This slurry contained all the fines, or —3/32 in., but also percentages of oversize, up to 1 % in., dependent on spills or breaks in screen jackets, a not uncommon occurrence in preparation plant practice. The flowsheet developed is shown in Fig. 1. Circled numbers represent points of sampling. Table I gives operational data including size, ash by size, composite ash, rate of flow in gallons per minute, percent solids dry weight, and average tons of solids per hour. It should be noted that these results are subject to human error in sampling practice. Detailed information reported is a representative evaluation of plant operation.

Jan 1, 1954

By Z. D’Amico

"IntroductionWE HAVE HEARD quite a lot recently on newer methods -of supporting roof, such as roof bolting or the use of metal props and •booms, but, with the exception of roof bolting, these methods are confined mostly to comparatively low, regular seams and even .bolting cannot be used to hold soft sides. Thus, where a seam of coal has great variations in thickness, or where it is faulty, or where the coal sides must be supported, nothing can wholly take the place of timbering with wood. This paper will deal mainly with the method of timbering such a seam, namely, the No. 3 seam mined by Brazeau Collieries, Limited, at Nordegg, Alberta, where the full height of a thick seam is mined in development. However, a few words on one or two other systems practised in Alberta when, in development work, a thick seam is only partially mined, should be of interest.Examples of Timbering in High SeamsThere .are several methods in use today for dealing with high seams of coal. The most popular is to develop the seam by driving road-ways in the coal by some conventional method, usually recovering the full thickness of the seam on the retreat. The following examples illustrate two variations of this method.In Figure I we have a thick •seam of friable coal, with a good roof, pitching about 30 degrees, which is being mined by taking the upper part of the seam in the development work, leaving the •bench coal in place. Figure 1A shows a section through a room."

Jan 1, 1954

By R. W. Jenkins

TRACKLESS equipment is being used by the Coplay Cement Manufacturing Co. to develop a folded limestone deposit economically and safely with inexperienced men. Cost and quality of development stone results in a saving when it is used in- stead of outside sources of limestone. This favorable cost has been attained by following a methods development and training program described in this paper. It is expected that further savings in favor of the mined stone will be made when stopes now being prepared are in production. The present equipment will be used for loading from stope draw points. The limestone is blended with quarried cement rock to serve as raw material for Portland cement, first produced in this country by Coplay Cement Manufacturing Co. from a process developed by its president, David 0. Saylor, in 1873. For many years the cement rock alone or with a small amount of added limestone was used for raw materials. Later as specifications were raised and the richer portions of quarries were depleted, limestone from outside sources was required in increasing amounts. In 1925 D. J. Uhle, the general manager, began to prospect company property for limestone.

Jan 1, 1954

By H. C. Chang, N. J. Grant

Creep of very coarse grained, high purity aluminum was studied at 400° to 1100°F with an initial stress range of 50 to 1200 psi. The process of boundary sliding and migration was studied. The driving force of boundary migration under creep conditions is shown to be a combination of strain energy migrationand surface energy. A theory is presented regarding the strainenergyrole the grain boundaries play under creep conditions. From this thetheory intercrystalline failure of commercial alloys can be explained. Also from this theory an optimum grain size should exist for good high temperature properties of high purity materials. IN the investigation of the creep of very coarse grained, high purity aluminum previously reported,' the cyclic nature of the process of grain boundary sliding and migration has been established by microscopic observation of the actual creep process as well as metallographically. It was also substantiated by measuring localized strains across the grain boundaries. In addition, it was shown how extensive subgrain and fold formation may result from boundary sliding and how the slid grain boundary may become sharply wavy as a result of subgrain formation. Since the publication of those results, additional information on the process of grain boundary sliding and migration has been obtained. It is the purpose of this paper to report on the direction and driving force of boundary sliding and migration, the effect of grain size, and the effect of temperature. Finally the effect of decreasing purity (alloys 2s and 3s) on the process of boundary sliding and migration is noted. From these results, an explanation is presented for the intercrystalline failure of alloys under creep conditions. The effects of grain size on the creep properties of impure and high purity materials are discussed in the same light. The experimental procedures and technique have been presented elsewhere.' It is only necessary to state how the 2s and 3s aluminum specimens are prepared. Machined specimens were first annealed at 600°F for about 12 hr. In order to produce a large grain size the specimens were then stretched 3 to 8 pct. The specimens were marked with reference marks, electropolished, annealed at 900°F for 24 hr and at 1150°F for 12 hr, and repolished. The grain size of 2s aluminum produced by this treatment is comparable to that of high purity aluminum in the direction of its width of the specimen, i.e., there are 2 to 4 grains across the width of the specimen. However, the grains of 2s aluminum are 3 to 10 times longer in the direction of the specimen axis. On the other hand, the grain size of coarse grained 3s aluminum ranges from 10 to 20 grains across the width of the specimen due to the treatment just outlined and therefore is much smaller than that of both high purity and 2s aluminum. As in 2s aluminum, the grains are about 3 to 10 times longer in the direction of the specimen axis than in the direction of the width of the specimen. The arrangements of the grains in 2s and 3s aluminum were generally irregular; therefore it was difficult to follow the course of the grain boundaries. Results Method of Presentation: In order to show the arrangement of the grains, especially the direction and positions of the grain boundaries, traces of the grain boundaries on the four surfaces of the specimens were unfolded and mapped out after macroetching. Figs. 1 and 2 show the structural development drawings of specimens P-3 and P-8 respectively. The two flat surfaces (of which the front one faces the microscope) and the round-edged surfaces will be called the "front surface" and "back surface" and

Jan 1, 1954

By D. S. Kingery

Efficient transportation is necessary to complement modern mechanized mining methods. The increasing trend toward high-capacity face loading equipment has demanded equally efficient haulage methods; this has been met by increasing mine-car sizes, using larger locomotives, and increasing haulage speeds, all requiring properly installed and maintained haulage roads specifically designed for this type of traffic. The recommendations and specifications included in this circular were made to point out salient factors important to the proper construction and maintenance of track haulage roads and to serve as recommended standards for track installation and maintenance. GLOSSARY OF TERMS USED Haulageway. - The track, walkway, trolley wire, feeder lines signal end telephone lines, signals, telephones, support, and drainage of the entry referred to. Subgrede. - The base upon which the ballast is laid.

Jan 1, 1954

By H. Clare Horwood

"Fractures and fracture zones containing veins and stringers of auriferous quartz in a quartz porphyry dyke are the principal structural features at the Howey and Hasaga gold mines. The 'break' containing the dyke was produced by a force from the northwest, the fractures in the dyke by compressive stress from the west.Both mines are in the north-central part of Heyson township, in the Red Lake area. They lie close to the southeastern side of the Dome granite stock. The Howey mine exhausted its ore reserves and ceased operations in November 1941. The Hasaga mine is producing at the present time (June, 1946).Mineralization was first discovered in the dyke in 1925 by the Howey brothers. Lorne Howey's discovery, which became the Howey mine, came into production in April, 1930; Ray Howey's find, which is now the Hasaga mine, started production in November, 1938.The total production from the Howey mine was 421,324 oz. gold and 144,253 oz. silver from 5,158,376 tons of ore hoisted ( 4,319,331 tons milled) during its 11 years of operation.The total production from the Hasaga mine from November, 1938, to December 31, 1945, was 124,434 oz. gold and 51,009 oz. silver from a total of 901,098 tons hoisted (721,361 tons milled).GENERAL GEOLOGYThe porphyry dyke containing the orebodies at the Howey and Hasaga mines lies a short distance southeast of the contact of a granite-granodiorite mass known as the Dome stock. The dyke fills a fracture trending N.65°E. in a tongue of Keewatin volcanic breccia that extends in a rather irregular manner into an elongate intrusive stock of dioritic rock known as the Howey diorite. The accompanying table presents the geological succession."

Jan 1, 1954

By K. R. Van Horn

RESIDUAL stresses in metals operate under a cloak of mystery, as they have neither been seen in the laboratory nor detected by means of the microscope. In spite of their phantom-like nature, they frequently exert metallurgical effects that cannot be ignored. In some cases the results have been detrimental, causing rejections or premature failures, but frequently the effects have been highly beneficial to the producer or consumer of metal products. First, however, what is a residual stress? When a metal is plastically deformed by bending, rolling, pressing, or by a phase transformation or precipitation from solid solution, or by a sharp temperature gradient resulting from nonuniform cooling, quenching, or welding, it remains in a state of strain. The strains or strain gradients produced by such operations and retained after all external forces are released are known as residual strains, and the accompanying stresses as internal or residual stresses. Many defects or failures in metal products have been ascribed to residual stresses, sometimes erroneously, because there was no other apparent explanation after the usual metallurgical tools of diagnosis had been applied. For example, during World War 11, the forged aluminum alloy aircraft cylinder head in the reciprocating engine began to replace the cast head with the familiar cooling fins. The fins were machined in the solid forged head by an ingenious milling operation. One plant reported an epidemic of excessive distortion during the delicate high-speed milling. A thorough examination revealed that the composition, heat treatment, mechanical properties, and metallurgical quality of these heads were comparable to those of forgings that machined satisfactorily. It was then claimed that the cause of the machining difficulties was connected with residual stresses resulting from the quenching during the solution heat treatment. An elaborate stress analysis actually demonstrated, however, that the magnitude of residual cooling stresses was lower in the cylinder heads which machined poorly than in those which were satisfactory in this respect. Subsequent tests proved that the machining problems in this case originated from variations in the tools and tool design. Sources of Residual Stresses in Metals Residual stresses are of two origins—mechanical and thermal. Thus, stresses may be produced in a metal by any cold-working process. The distribution and magnitude of these mechanically produced stresses can be calculated in a satisfactory, although approximate, manner for such simple cases as bending, torsion, and expanding of tubes. However, most manufacturing processes are too complex, and the original stress-strain relations in the products are not sufficiently known to permit calculation of the resulting residual stresses. Also, a specific process, such as wire drawing, may vary in complexity or uniformity of working, and large or small residual stresses may result, depending on the conformation of the dies and other features of the working process. Neither substantially unidirectional deformation, such as can be imparted by stretching a metal product having essentially the same mechanical properties throughout the cross section, nor deformation

Jan 1, 1954

By R. L. Grant

The conventional gallery test used by the Bureau of Mines Explosives Testing Station and corresponding establishments in other countries to establish the permissibility of explosives serves principally to differentiate the relatively safe explosive from the positively unsafe one. It has been recognized for many years that a more definitive test is needed to measure the relative incendivity to firedamp of explosives and explosive devices. A new method - the oxygen-value test - for measuring this incendivlty quantitatively has been devised and is being tested at Bruceton, Pa. To date, this testing bas been limited mainly to straight nitroglycerin dynamites. It is planned to study application of the method to permissible explosives in the near future. These results will be reported later. In the present report, permissible explosives will not be considered specifically.

Jan 1, 1954

Since the end of World War n, many important developments have taken place in the investigation of the phenomenon of brittle fracture in mild steel. Fractures in certain classes of welded ships, in welded bridges, penstocks, etc., focussed a great deal of attention on the interrelationships of design factors, service conditions, and steel quality on the generation of catastrophic failures.Much publicity has been given these major failures, and there is perhaps a tendency to forget that mild steel, under certain conditions, as well known to behave in a brittle fashion in a wide range of everyday engineering applications.For instance, many who are connected with the haulage and lifting of heavy loads will be familiar with the bright "crystalline" fractures of crane hooks and chains which sometimes follow sudden jarring; those concerned with the heavy pressing and shaping of steel plate will not be unaware that at times sudden brittle splits or tears will develop for no obvious reason in, say, rolled pipes or in dishings.In fact it will be evident upon reflection that in many cases the conditions which mild steel has to withstand during processing into an engineering part or structure are more severe than those it wili be called upon to endure during service. In this sense brittle fractu;res in mild steel are much more frequent than are commonly supposed.Two modes of fracture are now generally recognised to occur in metals, namely, shear and cleavage. The latter manifests itself by the so-called "crystalline" fracture (here...

Jan 1, 1954

By E. S. Moore

"The Michipicoten-Goudreau area, bordering on the northeast corner of lake Suferior, has had a tectonic history related to that of the geosyncline occupied by this lake. This basin has been a major structural feature in the Canadian Shield since at least late-Precambrian time. It has been extensively faulted and was the centre of great igneous activity in the Keweenawan feriod . Many of the faults, folds, dykes, and sills in the surrounding regions tend to head directly or indirectly into this basin. Some of the faults in the Michipicoten-Goudreau area appear to run under the eastern part of lake Superior just as the large Keweenaw fault in Michigan extends into the lake on the south side. Some of these faults may even be extensions of or counterparts of the faults on the south side of the lake. Another set of faults in the Michipicoten-Goudreau area runs nearly transverse to some of these major faults, and it is evident that in some places movement has recurred at a later time on faults formed in an early period.STRATIGRAPHYThe rocks of this area, with the exception of Pleistocene and Recent formations, are all Precambrian:"

Jan 1, 1954

By R. B. Allen, B. S. W. Buffam

"The property of Chesterville Mines, Limited, is in McGarry township, Timiskaming district, Ontario, about 25 miles east of Kirkland Lake. It consists of a group of fifteen claims that extend northeast from the KerrAddison mine for a distance of 2 miles.In June, 1906, two groups of prospectors left the town of Chesterville, Ontario, to prospect in northern Ontario. Silver had been discovered 3 years before at Cobalt and the large profits of this young mining camp were the principal incentive to extending the field of exploration northward. One group consisted of Dr. Reddick, Edward Flynn, John Hummel, William Knott, and Colin Cameron. The other group comprised J. T. Kearns, Herman Hummel, W. G. Barkley, and J. Elliott.The two groups travelled north by train to Haileybury and thence to Larder lake by canoe. Camps were pitched on the northeast arm of the lake, and within a short time a discovery was made by Edward Flynn of the first party, who found gold on the property now owned by Kerr-Addison Gold Mines, Limited. Herman Hummel and J. T. Kearns shortly afterwards made the second discovery, on what is now the Chesterville property. These discoveries, made some years prior to those at Porcupine and Kirkland Lake, are believed to be the first in that part of northern Ontario.The Hummel-Kearns claims were incorporated in the following year under the name of Chesterville Larder Lake Gold Mining Company, Limited. It was not, however, until 30 years later, in 1936, following the increased premium on gold, that sufficient capital was placed in the treasury of the Company to carry out an extensive diamond drilling programme. This exploratory drilling was started early in 1937 under the direction of Leo. J. Kearns, and a large body of ore was intersected in the first drill hole. Underground work was started in 1938, a mill was built, and the first gold brick was poured on July 29th, 1939."

Jan 1, 1954

By J. Marin, H. A. B. Wiseman

This paper presents results of an experimental study dealing with the plastic stress-strain relations of aluminum alloy 14s-T6 subjected to combined biaxial tension and compression stresses. Plastic stress-strain relations for both constant and various types of variable stress ratios were determined and a comparison made with the simple flow theory of plasticity. THIS investigation was undertaken for two main purposes: 1—to obtain plastic stress-strain relations for Alcoa 14s-T6 when subjected to various combinations of biaxial stresses, and 2—to determine the validity of the flow theory in predicting plastic stress-strain relations for combined stresses. The biaxial stresses used were tension combined with compression. These stresses were produced by subjecting a thin-walled tube to axial tension and torsion. Various types of combined stress conditions were investigated. To provide control test data and information on the influence of biaxial stresses on the strength, the usual constant stress ratio type tests were made. These tests showed that the biaxial yield strength agrees approximately with the distortion energy theory. However, the Prager semi-empirical theory agrees best with the test results. For these constant stress ratio tests the plastic stress-strain relations were found to agree approximately with the flow theory. (For constant stress ratio the flow and deformation type theories are identical.) In view of the fact that the constant stress ratio tests cannot distinguish between the flow and deformation theories, a number of variable and special biaxial stress tests were made. These tests showed that the flow theory is inadequate, since large differences exist between the experimental and theoretical results. Special tests were also conducted to check the validity of the isotropic yielding assumption. This assumption is made in the linear-type flow theory. In these tests specimens were loaded in tension to predetermined values beyond the proportional limit stress. The tension load was removed from the specimen and the specimen was subsequently loaded in torsion to fracture. Other tests were applied with the order of torque and tension loading reversed. The nominal stress-strain curves for these two tests approximately coincide indicating that the assumption of isotropic yielding is valid. In addition, these tests verified the requirement by the slip theory of plasticity that prestraining below 140 pct of the proportioned limit stress in either torsion or tension did not influence the subsequent plastic stress-strain relations in tension or torsion. Another type of test was conducted to check the assumption that the axes of principal stress and strain coincide during plastic flow and variable stress conditions. These tests were conducted by applying combinations of axial tension, internal pressure, and torsional loads such that the axes of maximum principal stress could be rotated through 90" during the loading path. The results of those tests showed that the angle between the axes of principal stress and strain varied greatly and that the assumption of coincidence between axes of principal stress and strain is not valid. Introduction In various metal processes including forming of sheets, rolling of bars, and extrusion of rods, metals are subjected to stresses beyond the yield strength of the material. Often these stresses are not simple stresses acting in one direction, but are combined stresses acting in more than one direction. Structural and machine members are often subjected to combined stresses. To adequately determine the factors of safety for these members, it is necessary to know the plastic stress-strain relations of the material used for various combined stress conditions. Various theories have been proposed for predicting the plastic stress-strain relations for combined stress in terms of the simple tension plastic stress-strain relation for the material. To determine which theory might be adequate, test results must be obtained for various combined stress conditions, in order to compare the actual with the assumed theoretical behavior. Although there is considerable test data available for combined stress conditions in which the principal stress ratios are constant, relatively little test information is available for vari-

Jan 1, 1954