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By H. M. Howe

(New York: Meeting, October, 1913.) 1. INTRODUCTION.-This paper gives the results of our micro-graphic determinations of the position of Ae3 in a series of 14 hypo-eutectoid steels of varying carbon content, one of them very rich in phosphorus, and of SEe for one hyper-eutectoid steel. We have pro-ceeded chiefly by noting the temperature -at which the reabsorption of the pro-eutectoid element is found to be complete after a 30-min. holding, but in part also by noting the temperature at which its precipitation begins. Observations on these same steels by Messrs. Burgess, Crowe, and Rawdon, of the United States Bureau of Standards, are given in a paper' issued simultaneously with this, while in a third paper s one of us compares these data with those of earlier observers. These three papers are treated as one whole by numbering their sections, tables, and illustrations continuously, and by setting the folding plates of micrographs at the end of the last paper. THE COMPOSITION OF THE STEELS EXPERIMENTED ON is given in Table I. Notation. and Definitions.-Following Osmond's development of Tschernoff's notation; in which " Ac3 " is the upper limit of the hypo-eutectoid part of the transformation range as observed in heating up, and " Ar3 " is that same limit as observed in cooling down, and following the usual custom of calling the upper limit of the hyper-eutectoid part of that range "SE," we may go farther and call this latter limit " SEc " when observed in heating up .and " SEr " when observed in cooling down.

Jan 6, 1913

By E. L. Bruce

THE district of. Patricia, in the province of Ontario, lies northwest of the Albany River and extends northward to Hudson's Bay. Formerly this was the unorganized district of Keewatin, the southern part of which was divided in 1912 between the provinces of Manitoba and Ontario. The interprovincial boundary now runs north from Lake of the Woods for 275 mi. and thence northeast 375 mi. to Hudson's Bay. This district is comparable in size to all the older part of Ontario south of the Canadian Pacific Railway east of Lake Huron-thus it is roughly one-third of the whole of the present provincial area. The central part of this great triangle is one of the least accessible parts of Canada. From it streams flow southward to the English River, southeastward to the Albany, northward to Hudson's Bay and the Hayes River, and westward to Lake Winnipeg. None of the streams is large and canoe travel is not easy. The only industry it has ever had is the trade in furs. Until the development of the airplane on a commercial basis, the only means of travel was by canoe or dog-train. There is not a mile of railway in the whole district. The two areas to be dealt with lie in the southwestern part of Patricia. Red Lake is 50 mi. east of the Manitoba boundary and 75 mi. north of the transcontinental railway from Cochrane to Winnipeg. Woman Lake is 50 mi. farther east and slightly farther north. The late Dr. D. B. Dowling, of the Geological Survey of Canada, visited Red Lake and spent some time there during his exploration survey from Lac Seul to Berens River in 1893. He also visited the Woman Lake basin during the same journey, but his examination of it was much less detailed, the great area covered by him during the one field season making it impossible to make more than a hurried reconnaissance. Some prospecting in the Red Lake district followed Dowling's exploration, but the distance from railway was too great for any systematic work to be done.

Jan 1, 1928

By D. A. Belforti, M. P. Lepie

Spectroscopically pure copper was melted on sapphire plaques in a zydrogen atmosphere. The surface tension of the liquid metal was determined using the sessile drop technique. Measurements were made by direct observation with the aid of a specially const,mcted telescope. The value obtained, 1268 dynes per cm, is compared to that found in the literature. THERE is at this time considerable interest in the use of ceramics for vacuum tubes. The crystalline material is superior to the more conventional glass in mechanical strength, chemical inertness, dielectric properties, ability to withstand high temperatures, and so forth. However, ceramics are much more difficult to seal hermetically with metals than are the glasses. For this reason an investigation was undertaken to determine the wetting and adhesion of metals to ceramics. The sessile drop technique offers a convenient means at elevated temperatures for measuring liquid surface tension, wetting angle, density, spread- ing coefficient, and work of adhesion. Thus, from the contour of a drop of liquid at rest on a solid surface one can obtain a quantitative evaluation of the degree to which the two substances will bond. To this end a special apparatus was constructed so that various molten metals could be observed. Standardization of the apparatus was done initially by measuring the surface tension of copper since this is well documented in the metallurgy literature. Although there are many methods available for the measurement of surface energy,'+ the sessile drop technique has been used most extensively for molten metals and ceramics.5"' Fig. 1 illustrates the dimensions to be measured. From these values, the surface tension of the liquid can be obtained using the Bashforth and bdams' equation and tables.

Jan 1, 1963

For the first time in its history the Institute will hold a meeting in the State of Arizona. A few years ago Arizona stood third in the copper-producing districts of the United States. Since that time, with the development of porphyry mines, the output has gone up with great rapidity until it not only is the leading district, but its output at the present time is at the rate of nearly double the Montana output, which now stands second in the list. In connection with this .development, most interesting departures have been made in methods -of mining, concentration and smelting. Principles of mining and metallurgy of the greatest interest will be covered by papers which will' appear in the Bulletin and be presented at Technical Sessions, while ample opportunity will be afforded for those who go to the meeting to see all the points of interest .to them. In addition, members will be well rewarded by the marvelous natural features to be seen on the trip, including 'the petrified forests, the cliff dwellings on the Apache Trail and the Grand Canyon of Arizona. It is planned to start the special train from New York, but members and guests may join the special at other points en route as indicated by the following schedule: ITINERARY . , Thursday, September 14th Lv New York, Grand Central Terminal.. ............... 5.30 p. m. Dinner in dining car a la carte New England Members via B. & A. R. R. . Lv Boston. ............. (Regular train). ............. 2.00 p. m. Lv Worcester. ........... (Regular train). ............. 3.12 p. m. , Lv Springfield. ........... (Regular train). ............. 4.37 p. m. Dinner in Dining Car a la carte Ar Albany.. ......... .New York Central R. R.. ....... 7.45 p. m. Lv Albany .......................................... 9.00p.m. Lv Schenectady.. .................................... 9.32 p. m. Lv Utica ............................................ 11.08~.

Jan 8, 1916

By L. A. Panek

Using an approach based on the theory of similitude, the author develops a general equation and related concepts that provide new insights to an old problem. The load-bearing capacity (strength) of a square, rectangular, or cylindrical prism of a brittle material such as rock, coal, or concrete is expressed as the mathematical product of a size effect, a shape effect, and a function of the mechanical properties (deformability, cleat/joint spacing, and friction) of the pillar, roof, and floor materials. Through an application of multivariate statistical analysis, the results of assorted tests (laboratory and in situ) and observations of failed pillars can be combined into a fundamental scaling equation, which provides a unified, consistent approach to the estimation of mine pillar strength. The form of the equation is sufficiently general to be able to incorporate refinements in the characterization of the structural parameters, as they become available through future analysis and experimentation. Analysis of the published test data suggests that pillar compressive strength (per unit of area) is proportional to the cube root of the pillar width, and that the height effect can be described as the superimposing of a variable size effect (characteristic of the material) on the constant width effect.

Jan 1, 1981

By Auguste J. Rosh

The use of titaniferous ores in the blast-furnace has been the subject of much controversy for many years. Divers objections have been raised against them, and, for one cause or another, the verdict

Jan 1, 1893

By James F. Kemp

In earlier gears, the custom prevailed of regarding the anthracite basins as cases of folding with slight development of faulting. Folding is so pronounced and, in the eastern and western Middle Fields, at times so violent, that the inference was a natural one and led to the widespread impression that practically all the disturbances of the seams could be explained in this way. The cross-sections and maps prepared forty or more years ago for the Second Geological Survey of P ennsylvania, by Mr. Ashburner under Prof. J. P. Lesley, exhibit little else than folds.' So far as I can discover faults fail in the charts, except in one small case in the Henry colliery near Plainsville on the outskirts of Wilkes-Barre. Some years ago, while spending a day or two in Wilkes-Barr, under the guidance of R. V. Norris, I looked over some recent and accurate cross-sections of a numbcr of the large collieries and was deeply impressed with the peculiar behavior of some of the seams and the intervening shales. Thus, a seam might present a small, more or less overturned fold, rising 30 to 50 ft. (9 to 15m.) above its general course, and yet the movement would be taken up in the overlying shales, so as hardly to be noticeable in the seams next above or below. These and similar anomalies, especially when shown with the accuracy of engineer's surveys, possess great scientific and practical interest, bearing as they do, not alone on coal mining, but on theoretical geology and the actual behavior of strata under great compressive stresses. In preparation for the semicentennial meeting of the Institute, an effort was therefore made to secure some of the most interesting sections for presentation to the members. The collection of illustrations here shown is mainly due to Douglas Bunting of the local committee, to whom and to the contributing companies acknowledgments are due. The illustrations are taken from all four of the main basins, but are chiefly from the portions nearest Wilkes-Barre. The first are in the

Jan 1, 1922

Although the mining industry faced ever-increasing risks and uncertainties in 1974, it nevertheless pushed ahead with considerable rapidity in exploring and developing new orebodies-while expanding and improving the technologies of mining and exploration. Prepared by the SME Mining and Exploration Division, this section of the annual review covers the pertinent worldwide developments in the fields of geochemistry, geology, geological engineering, open pit mining, underground mining, rock mechanics, operations research, and solution mining.

Jan 2, 1975

A knowledge of the principles of punctuation is essential to effective and intelligible writing, for the ease and pleasure of the reader, and even his understanding, may depend upon the choice and the placing of punctuation marks. To 'punctuate' is to mark with stops or points; the word comes from the medieval Latin punctuare (punctuatus), which in turn is derived from the Latin punctum, a point. The purpose of punctuation is to show the manner in which the writing is to be understood; to indicate the relations between parts of a sentence and between successive sentences. To some extent "it does for the eye what vocal stress does for the ear", but especially it marks logical relations. Some punctuation marks, such as those indicating admiration, exclamation, and interrogation, are rhetorical as well as grammatical, but most of the common ones are logical or grammatical. My discussion will be confined to grammatical punctuation in ordinary writing. "The problem of punctuation in text matter", as George Summey * says, "is to employ words, points, and paragraph breaks in such a way as to achieve at the same time clearness, proper distribution of emphasis, and the desired kind of movement." The criticism of the punctuation of a sentence or of a group of sentences is not final until the context, within the paragraph, is read. A paragraph is a sentence or a group of' sentences forming an independent unit of the composition; it represents a unit of thought. A multiplicity of paragraphs produces a choppy effect; on the other hand, paragraphs of excessive length are tiresome, because the belaboring of one unit of thought wearies the reader. The aim should be to

Jan 1, 1931

By A. J. Boyer, T. R. Meadowcroft

An experimental determination has been made of the efject of surface diffusion on the vapor pressure obtained in a Kwudsen cell. The results show that a knife-edge orifice in a molybdenum lid may give erroneous results for the vapor pressure of silver. when a correction suggested by winterbottom and Hirth is made, the results become meaningful. Experimental work with cylindrical orifices in molyhdenz~m lids and knife-edge orifices in ceramic lids shows that good vapor-pressure results may he obtained when the orifice is designed so that ejfusion is the only significant source of weight loss. THE Knudsen effusion cell technique has been used by many investigators to study relative and absolute vapor pressures over metals and alloys at elevated temperatures. As a result of this interest, some theoretical studies have been made of geometric factors affecting effusion from the orifice of a Knudsen cell. A review of these studies has been made by Margrave.1 Recently, Winterbottom and Hirth2 have suggested that a physical effect, that of condensation, surface diffusion, and re-evaporation, may seriously affect Knudsen cell measurements, especially when a knife-edge orifice is used. Inasmuch as many of the present vapor-pressure data have been obtained using knife-edge orifices. it was felt that an experimental evaluation of the effect of surface diffusion on Knudsen cell measurements would be of value both in the design of the cell orifice and in establishing realistic estimates of the limits of error for existing data. The experimental program was in two sections. Firstly, measurements of the vapor pressure of silver were made in cells with cylindrical and conical orifices in which the surface-diffusion contribution to the weight loss should be negligible. These results were correlated with existing data to give a reliable measure of the real vapor pressure of silver. Secondly, measurements made using knife-edge orifices were corrected using the surface-diffusion theory of Winterbottom and Hirth2 and were then compared to the real values. The experimental arrangement is shown in Fig. 1. The balance was an Ainsworth RV-AU-1 automatic recording microbalance capable of measuring weight changes of ±0.02 mg on a total load of up to 100 g. The temperature was measured by an optical pyrometer signted on the bottom of the suspended crucible. The temperature readings were calibrated in a separate experiment in which pyrometer measurements were made while at the same time thermocouple readings were taken of the temperature at the inside top and bottom of the crucible. The range of reproducibility with this technique was ±4°C. A constant voltage source maintained a temperature of ±2°C at 1200°C over 10 hr. Silver of 99.99 pct purity was used in nonporous alumina crucibles. Lids of molybdenum, tantalum, or magnesia were cemented to the crucible using a sodium silicate cement. Table I shows the characteristics of the lids used. The vapor pressure is obtained using the basic Knudsen formula:

Jan 1, 1965

By R. J. Charles

Previous study of simple impact systems indicated that energy required for fracture and size reduction of brittle materials is greatly dependent on the type of loading that is employed. In this regard it was postulated that fracture and size reduction of a brittle specimen might be accomplished by a high velocity impact at an energy level at which a low velocity impact would leave the specimen relatively undamaged. The finite time required to propagate energy away from the point of loading of an impacted object to other parts of the object and to its supports may permit a concentration of energy at the point of impact if the rate of loading is high. Localizing of energy at the point of impact could quickly initiate fractures that would propagate through the impacted material along with the traveling stress waves. As the cracks form, the initially absorbed strain energy would be released and portions of it travel ahead of the crack tips as stress waves. These secondary stress waves, combined with the initial stress waves derived from the impact, would produce high localized strain conditions in front of the fracture zone. The fracture zone would propagate and the specimen shatter. High rates of loading are brought about by short impact times, in turn obtained by employing high velocity projectiles that are of small mass compared to the impacted object.

Oct 1, 1956

By Irwin Roman

NUMEROUS results and formulas have been published for analyzing seismic records, but most of them apply only to large-scale phenomena such as are encountered in studying earthquakes. In a few cases,1 formulas have been published for some of the simpler structures. In the present paper, an attempt will be made to analyze several types of struc-tures without using methods more advanced than those of a first course in calculus. In, tracing a disturbance through a medium, it is almost always possible to base the analysis on Fermat's Principle of Extreme Time, which states that waves of displacement travel between points in such a manner as to make the time of travel an extremum with respect to all neighboring paths. In the simpler cases, comprising most of those used in optics or geophysical prospecting, this time is a minimum and the principle is often referred to as the Principle of Least Time. Within a homogeneous medium, having a uniform speed of transmission of the disturbance in all directions and throughout the medium, the paths are straight and are refracted at the interfaces in accordance with the Snell law of refraction, which states that the ratio of the sine of the angle, made by the ray with the normal to the interface, to the speed of trans-mission is the same on both sides of the interface. Thus, in any medium composed of homogeneous sections, this same ratio has a constant value at all points. In particular, if all interfaces are horizontal, it is apparent that the angles of incidence are the angles made by the ray with the vertical direction. Furthermore, the incident ray, the refracted ray and the normal to the interface are all in the same plane at each refraction;

Jan 1, 1933

By M. G. Nicholas

The influence of deformation, relative movement and surface cleanliness on the strength of room -temperature "interparticle" bonds between copper surfaces has been studied. No bonding resulted when clean surfaces were merely pressed together, even under pressures of 50,000 psi. Bonding resulted, however, when clean surfaces were simultaneously pressed and moved relative to each other, some bonding occurring no matter how small the pressure or relative movement. Exposure of the clean surfaces to various chemicals inhibited bonding, none at all being produced by small relative movements. The size of the movements which first produce bonding between exposed surfaces depends on the nature of the chemical, being less than 0.002 in. for cleansing reagents and greater than 0.004 in. for lubricants, water and hydrogen sulfide. It is concluded from the experimental data that the prime requirement for bonding is the dispersal of surface films such as oxides and adsorbed contaminants. THE formation of interparticle bonds during the room-temperature compaction of powder metallurgy components greatly increases the ease of handling in subsequent production operations prior to sintering. The strength of unsintered compacts follows the same general trends as their density and hardness, but quantitative data are extremely Scarce. Quantitative correlation of the data on the overall strength of a compact with that of the individual interparticle bonds is virtually impossible due to the extremely complex geometry of powder compacts. Qualitatively, however, the strengths of unsintered compacts can be correlated with variations in parameters known to influence the extent of cold bonding, and hence interparticle bonding, such as surface cleanliness, relative movement, and deformation of the mating surfaces. Kuzmic and seelig4 found that contamination of powder particle surfaces with lubricants reduced the strength of unsintered iron and copper compacts. Interparticle shear has been shown to promote bonding by Train and Hersey7 while Gregory has shown that die rotation is beneficial. Eilender and schwalbe6 concluded that most bonding occurred during the early stages of pressing iron powder compacts when interparticle shear is one of the principal processes occurring. mile there can be little doubt that these and other factors, such as particle size and shape, affect the extent of interparticle bonding produced by compaction, evaluation of the influence of individual factors is not easy. Particle deformation and relative movement, for example, occur simultaneously during compaction, making any precise measurement of their relative influences difficult. Because of these and other difficulties encountered in studying interparticle bonding in actual powder compacts, the approach adopted in this study was to

Jan 1, 1963

By J. A. Woolf, E. S. Leaver

The presence of soluble base metals in precious-metal ores usually precludes cyanidation as the best method of treatment. The laboratory experiments described in this paper show the possibility of cyanidation of gold-silver ores containing less than 0.5 per cent. of cyanide-soluble copper and the effect of zinc in the cyanide solution. Part I.—Copper in Cyanidation The proposed process of cyanidation of precious-metal ores containing copper is based on the regeneration of about 80 per cent. of the cyanide used in the dissolution of the copper. The method of regeneration involves a combination of the sulfide and the acid precipitation of the copper and silver. The resultant solution is made alkaline with lime, and the gold is precipitated with zinc dust. Solubility of Copper Minerals in Cyanide Solution In order to determine the solubility of copper minerals, including metallic copper, under the usual conditions for cyanidation, experiments were conducted with synthetic ores. Each ore sample was prepared by mixing the particular pure copper mineral with barren sea sand. Both the mineral and sand were ground to pass 100 mesh before they were thoroughly mixed. The percentage of copper in each head sample was determined by direct assay, excepting the metallic copper sample, which was computed on weights before mixing. Table 1 gives the results. Azurite, bornite, chalcocite, cuprite, malachite and finely divided metallic copper are readily and completely soluble under the usual conditions for cyanidation. Enargite and tetrahedrite are sufficiently soluble to cause an excessive loss of cyanide, and they also cause fouling of solutions with arsenic and antimony. Precious-metal ores containing small percentages of chalcopyrite or chrysocolla may give satisfactory returns with the usual cyanidation.

Jan 1, 1930

By R. H. Hawkins

An investigation of the applicability of geophyiical methods to northern Ontario lignite deposits was undertaken early in 1930 by the Ontario Research Foundation at the request of the Ontario Department of Mines Pre-Cambrian ... Syenite, granite gnciss, etc. Igneous intrusivcs . Lamprophyre dikes cut the Abitibi River and lover formntions. (Permission of Ontario Dept. of Mines) and was financed in part from a research grant made by the latter organization. The work to date has included gravitational, magnetic and electrical resistivity studies. The gravitational and magnetic measure-

Jan 1, 1934

By Henry F. Adams, Guy H. Ruggles

IN this paper the authors aim to chronicle the experience and salient points brought out in changing flotation reagents at a concentrator which had probably been using a mininium amount of oil at a minimum cost per ton, to a more complicated system requiring a partial chemical control. The original oils were coal tar and pine oil. The new reagents are lime, xanthate and pine oil. It was found that there were no insurmountable difficulties and eventually the cost of the new reagents per ton of ore proved to be very little more than that of the old. LIME PLANT When the question of handling lime came up there were two propositions open: (1) to handle the lime dry; (2) to handle it wet in the form of an emulsion. Granting that a dry lime feeder would function properly, delivering lime uniformly, the chief objection was the dust that would be raised when these feeders were being charged or operated, as the only possible location was on a gallery beneath which men were working. With this objection the handling of lime as an emulsion seemed to be the better scheme. The lime plant which was first installed was for experimental work on one section. This was gradually changed and developed until it was of sufficient size to accommodate 20 sections. The various changes will not be discussed and the following description deals only with the fully developed plant. Crude as it is, and perhaps somewhat expensive to operate, the lime-handling plant has been quite successful. Much has been learned which will pave the way for a better installation in the future. Burnt lime is received loose in standard gage box cars. This is the product of the kilns and has had no screening or sorting. A grab sample is taken from each car as it is unloaded. An average of the analyses of samples from 44 cars gave the following: [ ]

Jan 1, 1928

By H. F. Johnson, C. S. Harloff

The Nichols series system of electrolytic copper refining has successfully maintained its strong competitive position in the copper-refining industry of today; therefore the improvements made in accomplishing this result are of interest. While additional interest would lie in specific comparisons of results obtained in series operation with those in multiple, we have refrained from such a comparison because it can be fair to both only when they are operating under similar conditions on the same grade of materials. Historical The Nichols Copper Co. started a small refinery at Laurel Hill, using its present system, about 1892. The details of the process in its early stage of development were kept strictly secret, so that no information was published or interchange of ideas permitted with the staffs of other copper refineries, where the multiple system was being developed at the same time. However, the fundamentals of the process and type of cell used today differ very little from their earliest form. All operations including loading and unloading of tanks, and all transportation as well, were carried on by hand. The plant remained in this condition with a gradual expansion taking place until the World War forced such a rapid development that little time or thought could be devoted to modernization or mechanical improvement requiring careful design or detailed planning. Considerable progress was made, however. (1) Large refining furnaces were developed. (2) The old expensive air-lift type of circulation was abandoned in favor of the present system. (3) Operating technique was gradually developed to a high point of efficiency. (4) Tank construction and lining were greatly improved, the first concrete tank being installed in 1915. (This tank is still in operating condition.) (5) A new power plant was constructed. (6) Fuel oil was substituted for lump coal on the refining furnaces. (7) Mechanical casting of the finished product was accomplished. During this entire period the plant was particularly fortunate in receiving only high-grade, clean copper bullion coming principally from the Phelps Dodge mines in Arizona. This, together with the lack of

Jan 1, 1934

By F. Peter

I. GENERAL INTRODUCTION. TECHNICAL progress takes place in two directions: the improvement of methods, affecting the quality of the product; and increase in the economy of operations, affecting its cost. In the iron-industry, practice is pretty well settled, and. revolutionary changes of method are, for the present, not to be expected. Hence, in this industry, the principal endeavor is to reduce costs by the use of labor-saving inventions, such as the machines brought into use during the last decade. But it is not alone necessary to reduce the labor-cost; complete economy requires also a saving in raw material. Under this head we may rank the coal employed as metallurgical fuel; and it follows that progress includes the economic use of fuel, so managed as not to injure quality of product. In the present paper it will be shown how, by suitable utilization of the heat from the furnace, a large portion of it may be made available for other purposes. Such utilization of waste-gases is important in all industries which employ furnaces (especially heating- and smelting-furnaces); and in the first rank of these stand the iron-, glass-, and porcelain-manufactures. The following pages are devoted chiefly to the waste-gases of smelting-works, and especially to those reverberatory-furnace gases which are not combustible.'

Jan 12, 1913

By Hertha R. Freche

The diffusion of magnesium and silicon from the core into the high-purity coating of Alclad sheet is important commercially, and led to the use of a duplex product for the study of diffusion by means of spectro-graphic analysis of successive layers. It has been found that in the duplex materials the diffusion of magncsium from an undersaturated aluminum-magnesium alloy into its high-purity aluminum coating is approximately of the same order of magnitude as the diffusion of silicon from a saturated aluminum-silicon alloy into its high-purity aluminum coating. However, if magnesium and silicon are both present in the alloy in the ratio of Mg2Si, they appear to diffuse in the approximate ratio of this compound. Finally, if the alloy contains silicon in excess of the amount required by magnesium silicide, the amount of diffused silicon in the high-purity aluminum coating will also be in excess. The interdiffusion of metals in the solid state is of both scientific and technical interest, because it is helpful in the study of the alloy structure and in the solution of problems pertaining to the strength and surface condition of the fabricated product. W. C. Roberts-Austenlt carried out the first quantitative determination of the coefficient of diffusion of gold into lead. This classical experiment was followed by a series of investigations on the diffusion of metals and nonmetals in iron and steel and in nonferrous metals and alloys. Recently the diffusion of copper in coated strong aluminum alloys was investigated by A. Burkhardt2. This appeared to be the first published investigation on the diffusion of metals into aluminum. The present investigation was the direct result of a technical question in connection with alloy fabrication and is a summary of some preliminary work pertaining to the diffusion of magnesium and silicon into aluminum. The results necessarily will be subject to some variations, since this is the first attempt to evaluate the coefficients of diffusion of magnesium and silicon into aluminum according to this method of procedure. This

Jan 1, 1936

By Andrew Hyslop

In our never ending search for new and better ways of underground mining, we find that transportation has had its share of new ideas in the past few years. The old and still effective method of track haulage has had some competition from rubber-tired cars and belt conveyors, each of which has its own safety hazards which demand close scrutiny in any safety study. The use of shuttle cars, in particular, has introduced clearance hazards caused by the absence of the more or less positive guides formed by the rails of a track sys- tem; likewise the requirement of greater clearance tends to increase roof hazards which we all know to be great enough with the best of methods. However, the subject of transportation hazards is too broad to be covered entirely in one paper, so I will confine myself to track methods which carry the preponderance of underground tonnage. I am quite sure that to this group it is an evident fact that haulage accidents are of major importance. However, to stress the point, it may be well to look at a few figures. Safety statistics can be quite boring and often are subject to question as to mathematical accuracy because of different

Jan 1, 1949