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By H. Q. Golder

INTRODUCTION The stabilization of slopes is not a design problem. A slope is designed before it is made. For a slope to be stabilized it must already exist. The basic problem has existed for a long time. It started with cuts in soil and rock made in the 18th century during the construction of the canals which were developed at that time, and continued into the 19th century with the development of the railways, and in the 20th century with motor roads and lately open pit mining. It is not difficult to stabilize a slope, but certain questions must be asked and answered. These are: i) How much stability is required? ii) For how long is it required? iii) How important is the cost? These three questions indicate the basic problem of Civil Engineering, which is that the solution to any problem is a compromise between safety, cost and time. Stabilization of slopes is no exception. If the slope exists why is stabilization a problem? There are many possible reasons, for instance, a neighbouring and similar slope may have failed, or it may be necessary to change the conditions of the slope, steepen it, increase its height, put weight at the top, or construct a building at the foot in which case added security is required, or guarantee its stability for a longer time. MECHANISM OF FAILURE In order to pick the correct method of stabilization the mechanism of failure must be understood and the immediate cause of failure known. Often to remove the cause is the best remedy. The mechanism of failure has been studied over a period of many years in landslide problems. Pit slope failures are very similar to some types of landslides. (1) (2) (3) (4) In one sense there are many causes of landslides. Terzaghi lists 19. This means that there cannot be a standard solution to a stabilization problem. In another sense, it can be said that there is only one cause, which is gravity. This is a constant, never failing force which cannot be

Jan 1, 1971

By J. Tarwater

The torsional testing of cylindrical medium-carbon steel specimens, heat treated to a high strength level, revealed a stress-strain relationship that was dependent on the direction of torsional plastic pre-strain. This Bauschinger effect was observed in prestrained specimens both with and without subsequent elevated-temperature strain aging. Yield stresses in strain-aged specimens exceeded those of simply prestrained specimens and the difference in stress was greater when the prestrain direction opposed the test direction. This behavior is discussed in terms of the classical dislocation pile-up using Cottrell's equation, A plastically prestrained strain-hardenable member, loaded in a direction opposite to the direction of prestrain, produces a stress-strain relationship differing appreciably from the curve representing reloading in the prestrain direction. This phenomenon, referred to as the Bauschinger effect, will be discussed in terms of the stress differences ob- served at a specified strain. The effect, dating back to the 1880's, was first attributed to grain boundary stresses. When later work revealed that the effect was also present in single crystals, revised theories attributed the diminished applied reverse stress to assistance from internal long-range stresses. These stresses have been associated with dislocation pile-ups or with dislocation arrays having analogous stress patterns. The stress patterns are subject to alteration by interaction with interstitial solute atoms and acceleration of the interaction may be accomplished with elevated-temperature strain aging. As discussed herein, the interaction showed a directional effect with regard to the applied stresses necessary for small plastic strains. Aside from the rigorous Bauschinger stress-strai relationship, which compares prestrained members, it is interesting to compare the stress-strain curve of a member being prestrained with that of a prestrained member being reverse loaded. For small strains which are a fraction of the prestrain deformation, the applied stresses of the reverse reloaded member are smaller. However, as the reverse strain approaches the prestrain value, the stresses approach equivalence. It has been reported1 that the stress required to return a prestrained specimen to its initial "zero" position generally exceeds the prestrain stress because of the work hardening occurring on potential slip systems during prestrain.

Jan 1, 1963

By P. de Vitry, Oliver Bowles

THE conventional wire saw, introduced in the slate district of Pennsylvania by the Bureau of Mines in 1927, and used thereafter with remarkable success, consists of a three-strand steel cable having a diameter of 3/16 or 1/4 in. The equipment, methods used, and accomplishments have been described in previous reports.1-7 Similar wire saws have been used extensively in Europe, in quarries and in shaping blocks and slabs. During the period 1932-1937, competition in European marble quarries was keen, prices were declining, and orders were not abundant. When orders were received, there was generally an urgent call for speedy delivery. Because of the diversification of demands, it was impossible to maintain in stock marbles of the color, size, and thickness called for, therefore the material generally had to be fabricated after the order was received. The wire saw enabled stone mills to fill such orders promptly. With skillful handling, 7/8-in. slabs could be cut accurately and rapidly with this equipment. It was found, however, that, as the three-strand wire became worn, the cutting speed dropped rapidly and the cut became less accurate. To overcome these difficulties the junior author of this paper, after much experimentation, developed a new type of wire consisting of a single ribbon-shaped strand, twisted as shown in Fig. 1. To ensure straight sawing, the twist of the ribbon is reversed from right to left and vice versa every 25 ft. The reversal of the [ ] twist is shown in Fig. 2. This is not a new feature; it has been used to advantage with the three-strand wire both in Europe and America for several years. However, some difficulties arise in splicing the three-strand reverse-twist wire, and the claim is made that cutting is less accurate as the wire becomes worn. To make an endless belt, the ends of the single-strand wire are brazed together with

Jan 1, 1941

By David Reger

LITTLE new oil was found in West Virginia, during 1923, but there were important discoveries of gas. Most of the large oil producers have contented themselves with pumping old wells or in drilling only enough new wells in defined territory to maintain a fairly constant production, the attitude being that no, profit is made in producing high-grade oil at a low price and that an eventual loss is sustained by draining the reserves of a limited commodity that, at some more favorable time, will be of much value. The representative of one large company said: "We have done nothing but pump old wells during 1923 and we have made no plans for 1924." Careful attention to producing wells has been the rule, there having been few abandonments; the belief is prevalent that small wells will eventually become profitable under more favorable marketing conditions. In natural gas, the opposite point of view prevails. Because of the vast capabilities of the state for producing gas, its output being ahead of all others, great systems of transportation and distribution into the markets of four adjoining states have been built and a demand has been created that no present, or apparently potential, production can satisfy. This demand has become so great that large distributing companies not only discourage new applications for service but advise old customers to install coal furnaces for auxiliary fuel; some have requested public-service commissions to grant higher 'rates against large industrial consumers than those allowed for domestic heating. The response to this known market has been a rapid increase in price, both at the well mouth and at the door of the ultimate consumer, and the industry has become so stable that the only uncertainty, or hazard, appears to be the question of the presence of gas in fair quantity in a given territory under consideration. Several oil companies have now forsaken their policy of selling gas, wells outright when drilled and ;have organized gas departments to drill for gas and to dispose of the daily output by meter to distributing corporations. With such companies and with other producers whose interest is chiefly gas, the year has been busy and profitable. Some new territory of apparently large value has been proved and deeper producing sands in old fields have been tapped.

Jan 3, 1924

By J. P. Nielsen

When two grains in a polycrystalline specimen meet at a point in the course of grain-boundary movements, and the new boundary created at the point is one of relatively low specific free energy, a nonequilibrium boundary condition occurs. The nonequilibrium is enhanced if the other grain boundaries involved at the point of meeting are relatively high in specific free energy. The nonequilibrium results in a correction by growth of the complex grain (two subgrains) to a large size, sufficient in many cases for it to become a self-propagating unit, i.e., a recrystallization grain. This mechanism, herein called "geometrical coalescence," is proposed as a logical origin for recrystallization nuclei, particularly for secondary recrystallization. RECENT publications1-' indicate that considerable progress has been made toward a complete understanding of the three microstructural processes in metals: recovery, recrystallization, and grain growth. However, a major problem persists, namely, the origin of recrystallization nuclei. It is generally accepted that once a recrystallization nucleus, a secondary recrystallization nucleus particularly, has reached a certain size, it will continue to grow at the expense of its neighbors, simply as a consequence of grain-boundary free-energy considerations. What has remained obscure, however, is the mechanism whereby such a nucleus comes into being and grows to the self-propagating size. Recrystallization Nucleation in a Two-Dimensional Grain-Boundary System In the left portion of Fig. 1 is shown schematically the meeting of grains 1 and 4 on disappearance of boundary 2-3, i.e., the boundary that existed between grains 2 and 3, as might happen in the course of normal grain-boundary migration. If, by chance —and the probability is not necessarily small— grains 1 and 4 are close together in their mutual orientations, or in some other special way mutually oriented so that the new common boundary has relatively a very low specific free energy (hereinafter referred to by s), then the grain boundary arrangement as depicted in the figure is highly unstable. This is particularly so if boundaries 1-3, 3-4, 4-2, and 2-1 are high in their s values. Assuming, for the sake of argument, that boundary 1-4 has a s equal to zero, and the s's of all the other boundaries present are equal to each other and constant, then the boundary arrangement on the right in Fig. 1 will be

Jan 1, 1955

By E. H. Kelton

The purposes of this paper are to describe the use of adjustable cut and draw tools as a control test of drawing properties and to point out that no other well-known test or combination of tests determines this quality in zinc and zinc alloys. Rolled zinc has been used for making drawn articles, particularly battery cans, for many years. The development of rolling treatments satisfactory for these purposes followed the usual course of trial and error experimentation depending upon cooperation with customers to determine what type of material was suitable. A quick test of drawing quality was highly desirable, of course. Scleroscope hardness and temperll having no apparent relation to drawing quality, were used simply to check the duplication of rolling treatment and grade of metal. The dynamic ductility1 test, on the other hand, was believed to be so like the drawing operation as to provide a reliable index and came to be taken as the criterion of good drawing properties. Faith in this test was strengthened by the fact that metal having the highest ductility was more satisfactory for operations, such as the manufacture of battery cups, that required several redraws. No distinction was made at that time in specifying metal as to whether it was to be subjected to simple cut and draw, redrawing or forming operations. It developed, however, that in some grades of metal the highest ductility did not coincide with the most satisfactory quality when the material was used for a single draw. When zinc-base alloys, with their wider ranges of effective rolling treatments, came into increased use, their dynamic ductility and drawing quality appeared to have no connection whatever. Furthermore, comparisons of known drawing quality with other physical properties of the metal, including tensile strength, elongation and dynamic cold bends, were fruitless in yielding any clear relationship. Almost any test value produced in one piece of metal could be duplicated by another rolling or annealing treatment with attendant different drawing characteristics.

Jan 1, 1934

By J. E. Cannaday, R. J. Austin, R. K. Saxer

PREVIOUS investigators have determined activation energies and have postulated various controlling mechanisms for creep.'-' Recently Barrett et 01.I5 have suggested, as the result of their work with cadmium, that the apparent activation energies for creep (AHc) above 0.5 T, could be correlated by means of activation energies for self-diffusion (AHSD) and modulus of elasticity functions: AHC = AHSD - (5RT/E) dE/dT. The wide disparity of apparent activation energies previously obtained with nickel compared to those reported for other fcc metals and the desire to test the postulate of Barrett el al. prompted this study. The as-received 17.5-mil nickel wire used during this work assayed 99.87 pct pure, Table I. X-ray analysis indicated that the wire was in a stress-re- lieved state and metallographic examination revealed an equiaxed grain size of approximately 0.01 mm. Specimens degreased in acetone and cut to 1-1/2 in. lengths were tested in a cam-mechanized constant-stress creep machine. A vacuum of at least lo-5 mm Hg was maintained during all tests. Stresses were applied when thermal equilibrium was established. When a measurable (at least 0.5 pct) secondary creep was observed, the temperature was pulsed to a higher temperature. Pulsing time varied from 30 sec at 480°C to 2 min at 1300'C and above. Slopes of creep curves were determined after the initial acceleration in the strain rate had subsided and steady-state creep was achieved. To confirm the results obtained, additional tests were performed incorporating a temperature pulsing method suggested by sherby. In this method the load was removed during temperature pulsing and reapplied after thermal expansion had occurred. No appreciable differences in results were obtained. Tests were performed over a wide range of temperature (470" to 1310°C) and stresses (250 to 17,000 psi). The expression was used to calculate activation energies. In this expression T1 and T2 are the initial and final temperatures, and el and i2 are the creep rates at T, and T2. The variation of the apparent activation energies with the mean test temperature calculated by means of Eq. [I] are shown in Fig. 1. The mean test temperature (Tmean) was calculated from the relationship

Jan 1, 1967

By D. Harrington

One of the main functions of the United States Bureau of Mines is to obtain and disseminate information that will promote safety in and around mines, and the health and safety of employees engaged in mining. Serious health and safety conditions arising out of contamination of air in metal mines by dust, fumes from explosives and fires, and absorption of oxygen by timber and other causes, led the Bureau of Mines to cooperate with the United States Public Health Service in the study of dust occurrence and ventilation in metal mines in various parts of the country. A. J. Lanza, of the U. S. Public Health Service, and Edwin Higgins, mining engineer of the U. S. Bureau of Mines, in 1915, made a detailed study in the mines around Joplin, Mo.; their reports1 are now available. In 1916, 1917, and 1918, a similar study was made in the Butte, Mont., region by Doctor Lanza and D. Harrington, mining engineer of the Bureau of Mines; the reports of this investigation will be available soon. In 1919, the study was continued in some of the Arizona mines by D. Harrington, of the Bureau of Mines, and G. E. McElroy and R. A. Koronski, of the U. S. Public Health Service, the underground work being completed in June, 1920; these reports are now being prepared for publication. In the spring of 1920, the scope of the work was extended, with D. Harrington in charge as supervising mining engineer, and short studies were made in the mines of the Coeur d' Alenes in Idaho and around Oatman, Ariz. It is hoped soon to extend the work into mines of California, Nevada, Colorado, Michigan, and Minnesota, and ultimately to other states should the mining companies be willing to coöperate. While the coöperation of the mining companies is necessary, the companies are put to practically no expense other than supplying a guide to accompany the investigators underground, the length of time spent

Jan 1, 1922

By Oscar A. Glaeser

The purpose of this paper is to present specific applications of the fundamental principles of mine ventilation and the means that are at our disposal to accomplish the task of maintaining a healthful atmosphere in small mines and prospect openings. Need for Ventilation The range between the maximum oxygen content of normal air and the minimum safe content is extremely narrow, approximately 5 per cent. Furthermore, normal air must not be contaminated with irrespirable gases beyond definite limits, and mineral dusts are equally dangerous, although health impairment is slower. Tables 1 and 2 present the more common respiratory hazards encountered in mines. Adequate ventilation is the most effective means available to reduce or eliminate these hazards. Mechanical ventilation has reached varying stages of perfection in coal mines and in many large metal mines. The small mines and prospects rarely have a definite plan of ventilation. As a consequence underground workers are frequently exposed to health and accident hazards. The annual reports of fatalities in mines in the Western States record yearly many deaths due to asphyxiation and deaths caused by men falling down shafts and raises after being overcome by gas. At times mining operations are slowed up because there is no means of driving out the gas after blasting. For that reason only one shift is worked, or men wait from one to several hours for the "smoke" to clear out. Methane gas in varying quantities is widely distributed throughout California. It has been encountered in explosive concentrations in the coast range. It has been found on the Mother Lode and in quicksilver mines near the coast. Methane explosions have not been uncommon in underground operations and in tunneling jobs. These conditions and records indicate that there is room for improvement in mine-air conditions.

Jan 1, 1937

By J. A. Church

I. Early Furnaces,......423 11. Experiments with the HIgh-Shaft FURnace,..... 426 III. ExperMents wIth the Wide FURnace,..429 IV. ExperEentS with Extreme BOSH,... 43.2 V. Survival of the 56 by 180 IN. Furnace,.434 VI. Recent ExpeEiments,.....436 VII. SUMMary,........438 I. Early Furnaces. Copper blast-furnace construction in America has long recognized a general standard in the rectangular water-jacketed shaft with separate forehearth. The details, however, and especially those relating to shaft dimensions, have had to meet a great variety of conditions, and show no uniformity whatever. Selecting a few of the present day Western plants, we find furnace lengths varying from 12.5 to 87 ft., widths at tuyere level from 42 to 84 in., and heights above tuyeres from 5 ft. 4 in. to 22 ft. 4 in.; and comparing present designs with those of the past, we meet contrasts no less striking. Unlike its transverse section, the length of a furnace has come to depend rather on the size of unit desired than on the requirements of smelting; and if the question of length be ignored, several of the various existing designs can be grouped together on the basis of a common transverse section. This section, having a width at tuyere level of 56 in. and a height above tuyeres of 18 ft., was developed at Great Falls, and the story of its development contains some interesting features. Ground was broken for the Great Falls works in the spring of 1891. About a year later, the concentrator was able to begin operation, followed within the next few months by the Brueckner, reverberatory, and converter departments, and in April, 1893, by the first blast fur-

Jan 1, 1914

By S. B. Lement

THE nature of the carbides that form during the tempering of martensite is a subject of continuing controversy. The only direct methods of identification available are X-ray and electron diffraction. These methods are subject to several difficulties. Only a relatively few diffraction lines of appreciable intensity emanate from carbide phases that are formed at low tempering temperatures. Furthermore, some overlapping of carbide and matrix lines occurs. There is also the problem that numerous lines in the patterns of possible carbide phases that may be present have about the same d-spacings. Increasing the number of carbide lines and eliminating the matrix lines can be accomplished by extraction techniques. However, there is always the possibility that a change in carbide structure will occur as a result of removal from the parent matrix. Therefore, such techniques as electrolytic extraction and making extraction replicas should be checked by other methods. For identifying small amounts of carbide in a tempered martensitic matrix, electron diffraction carried out in reflection is more advantageous than X-ray diffraction. To properly prepare a specimen for reflection electron diffraction, an etchant that will selectively attack the matrix and thereby cause the carbide particles to stand in relief should be used. With an electron beam directed at a grazing angle to the specimen surface, the major contribution

Jan 1, 1960

By Herbert Clark Hoover, Lou Henry Hoover

GEORGIUS AGRICOLA was born at Glauchau, in Saxony, on March 24th, 1494, and therefore entered the world when it was still upon the threshold of the Renaissance ; Gutenberg's first book had been printed but forty years before ; the Humanists had but begun that stimulating criticism which awoke the Reformation; Erasmus, of Rotterdam, who was subsequently to become Agricola's friend and patron, was just completing his student days. The Reformation itself was yet to come, but it was not long delayed, for Luther was born the year before Agricola, and through him Agricola's homeland became the cradle of the great movement ; nor did Agricola escape being drawn into the conflict. Italy, already awake with the new classical revival, was still a . busy workshop of antiquarian research, translation, study, and publication, and through her the Greek and Latin Classics were only now available for wide distribution. Students from the rest of Europe, among them at a later, time Agricola himself, flocked to the Italian Universities, and on their return infected their native cities with the newly-awakened learning. At Agricola's birth Columbus had just returned from his great discovery, and it was only three years later that Vasco Da Gama rounded Cape Good. Hope. Thus these two foremost explorers had only initiated that greatest period of geographical expansion in the world's history. A' few dates will recall. how far this exploration extended; during Agricola's lifetime. Balboa first saw the Pacific in 1513 ; Cortes entered the City of Mexico in 1520; Magellan entered the Pacific in the same year ; Pizarro penetrated into Peru in 1528 ; De Soto landed in Florida in 1539, and Potosi was discovered in 1546. Omitting the sporadic settlement on the St. Lawrence by Cartier in 1541, the settlement of North America did not begin for a quarter of a century after Agricola's death. Thus the revival of learning, with its train of Humanism, the Reformation, its stimulation of exploration and the re-awakening of the arts and sciences, was still in its infancy with Agricola. We know practically nothing of Agricola's antecedents or his youth. His real name was Georg Bauer (" peasant "), and it was probably Latinized by his teachers, as was the custom of the time. His own brother, in receipts

Jan 1, 1950

By T. G. Chapman

THE writer has carried on experimental work for several years with respect to the simultaneous dissolution of gold by cyanide and the adsorption of the dissolved gold on activated charcoal in ore pulps, followed by the recovery of the charcoal by flotation. The results of this experimental work have been sufficiently encouraging to suggest a new process based on the principle of simultaneous dissolution and adsorption of gold, applicable to certain ores and tailings that cannot be treated to advantage by countercurrent decantation or filtration. Applications for patents have been filed and The Dorr Company, Inc. has the exclusive right to license the use of the process. The purpose of this paper is to describe such a process, state its possible advantages and immediate field, and give some results obtained on a laboratory scale. EARLY EXPERIMENTAL WORK In the early stages of the experimental work attempts were made to precipitate soluble gold from cyanide solutions with zinc and aluminum in ore pulps followed by flotation of the precipitated gold, but since the results were not promising enough to continue with these precipitants attention was directed to carbon. The first experiments with carbon comprised the addition of cyanide and alkali to the ore pulp, the addition of carbon at or near the end of the dissolving period, and the recovery of the carbon by flotation. With this method of procedure the assumption was made that carbon functioned as a precipitant of gold from cyanide solutions and as such should be added as are other precipitants, including zinc and aluminum; namely, at the end of the dissolution period. The assumption was then made that carbon functioned as an adsorbent, and that if such assumption proved to be correct, it could be added with success to the ore pulp at the time of adding the cyanide. The first experiment along this line was successful in that the feasibility of the dissolution of gold by cyanide and the simultaneous extraction of the dissolved gold by carbon in ore pulps was demonstrated, at least with respect to such treatment on a laboratory scale.

Jan 1, 1939

By H. W. Gillett

Many of the parts of motor cars, aircraft, etc., that require strong light construction, hence must be made of high-quality steel, are stressed to the maximum limit only in a very small volume. In parts subject to bending stress a line or even a point may take the maximum stress. A series of endurance tests under repeated bending in progress in the U. S. Bureau of Mines laboratories, like similar tests by other investigators, has shown the great difference in life of sister bars of the same stecl, handled in the same way and tested at the same nominal stress. It is known that a surface notch or scratch greatly increases the local stress over the nominal calculated stress; internal notches, such as those formed by inclusions or sonims, probably have a similar effect. From the tetss made by the Bureau of Mines, the cleanliness of the steel at the dangerous section, or point of maximum stress, seems to be one of the most important factors in determining the life of the piece. The more localized the stress, the more does chance, rather than the average properties, dctermine the life of the steel. The usual test, a tension test of a bar taken longitudinally, is not sensitive to the local drop in strength (or tendency to increase the true local stress over the nominal) because of inclusions, which probably have a more injurious effect in hard heat-treated steels, such as must be used when great strength is sought, than in softer steels. Users of steel who make transverse tests find surprisingly low ductility on transverse bars of dirty steel, though the longitudinal tests may be good. Bending tests, reverse bending tests, and notch-bar impact tests,

Jan 1, 1923

By Felix B. Shay

The Agua Fria mine is in eastern Honduras at Lat. 140" 06' N., Long. 86" 36' W. Danli, the seat of the local municipal government, is the nearest town. The property is approximately 44 miles east of Tegucigalpa, the terminus of a truck road from the Pacific coast. The mine lies at an altitude of 3300 ft. with surrounding elevations as high as 6000 feet. For 20 years the oxidized croppings of the Agua Fria vein had been worked intermittently when in 1927 an attempt was made to open the property. A shaft was sunk 300 ft. and considerable ore was blocked out, but before a mill could be installed financial difficulties arose and the mine reverted to the original owners. Erle Y. Halliburton, of Los Angeles, purchased the property in 1934. At that time a careful consideration of all factors involved showed that air transport was the only practical method of moving the equipment and machinery necessary to commence production. The other alternative was by muleback, which required sectionalizing all equipment to a maximum load of 200 lb., and during the rainy season this type of freighting was subject to serious delays. It was decided to purchase a trimotor Ford powered by three Pratt and Whitney Wasp B motors developing 400 hp. each. There were several reasons for the choice: (1) this type of plane was available at a reasonable price, owing to its replacement by faster models on most of the airlines in the United States; (2) the ship was capable of carrying a pay load of 3000 Ib. over the required distance; (3) since this airplane had been widely used there would be no difficulty in securing competent personnel or in purchasing spare parts. It was necessary to rebuild the plane for cargo servicc. The windows were removed and the fuselage was entirely covered. A hatch was cut in the top of the fuselage to receive heavy crane loads and pieces of freight that were too large or too long to go through the rear door. The seats were removed and the interior of the plane was lined with Duralumin sheets. A heavy-duty landing gear was installed and the floor was reinforced. The nearest site for an airport was two miles north of the mine. The necessary grading was done by a small track-type tractor with a wheeled grader, which was brought in overland. Six weeks was required for bring-

Jan 1, 1940

By Benjamin N. Webber

Many of the auriferous placers of the arid Southwest differ widely from the standard types of stream and eluvial deposits of more humid regions, although exhibiting some of the features of each. This divergence in characteristics is of geological and economic importance and appears sufficient to warrant the consideration of these placers as a class distinct from both stream and eluvial deposits. It is hoped that the consideration of these auriferous gravels as a distinct type of deposit will facilitate recognition of morphological and economic features that might remain obscure if these deposits were viewed in the light of stream or eluvial placers whose type locality is a more humid environment. "Bajada placer" is proposed as the designation for this type of placer deposit. Bajada is the Spanish term for slope and is used locally in the Southwest to indicate the lower slope of a mountain range, the portion consisting of rock debris and standing at a much lower angle than the rock slope of the range proper. It has been used in a geologic sense by Schraderl and others. The type locality of bajada placers is the Sonoran Desert,2 where they occur on the bajada or rock debris slope of desert ranges. Stream placers are represented in the Southwest, but most of them lie within the mountain topographic province, the Mexican Highlands2 section of the Basin and Range physiographic province. Eluvial placers may occur in the mountainous semiarid Mexican Highlands but are almost unknown in the extremely arid Sonoran Desert, as mountain slopes are generally too steep to permit the accumulation of any considerable mantle of residual debris. Since their salient distinctions are almost wholly the result of formation under conditions of extreme aridity, bajada placers are largely confined to the Sonoran Desert, although a few occur in the adjacent Mexican Highlands. They may be modified by the action of ephemeral streams, in which case the placer gravels of these arroyos approach stream placers in type and habit of occurrence, but their relation to an arid environment and the bajada type is usually apparent.

Jan 1, 1935

By Walter Crafts, John L. Lamont

An investigation has been made of the multiplying factors for some of the more common alloying and deoxidizing elements for use in calculating hardenability of steel according to Grossmann's method. The factors for manganese, silicon, and aluminum that were reported in an earlier communication2 have been confirmed by microscopic determination of the half-martensite structure rather than on the basis of an empirically determined hardness corresponding to a half-martensite structure. Measurement of ideal critical diameter by microscopic examination was found to be necessary for other alloying elements, and multiplying factors for nickel, chromium, molybdenum, zirconium, vanadium, titanium, and boron have been determined. The nature and order of magnitude of the multiplying factors reflect the effect of the alloying elements on the structural character of the steel. Except for nickel and vanadium, the multiplying factors agree fairly well with previously published results. Good correlation between actual and calculated ideal critical diameters has been found in developing the multiplying factors and in checking the results against fairly simple steels. However, some discrepancies have suggested the need for a more thorough study of low-carbon and complex steels. Testing Procedure The investigation was conducted principally on steels made at the Union Car- bide and Carbon Research Laboratories, Inc., in high-frequency induction furnaces using Armco iron and standard alloying materials. However, a few open-hearth steels were used in establishing the effect of nickel, and the hardenability factor for boron was based primarily on open-hearth steels. All bars were normalized prior to the machining of Jominy hardenability specimens. The Jominy test was carried out under conditions standard for the test.3 Austenitizing temperatures judged to be appropriate for the compositions of the steels were used. Chemical analysis was determined on a sample taken adjacent to the Jominy specimen. Residual amounts of phosphorus, sulphur, nickel, chromium, molybdenum, and copper were determined on only one heat of each group made with the same materials during the same period. "Acid-soluble" aluminum and zirconium rather than total amounts were determined, as it is considered probable that the acid-soluble amount is more representative of the effective alloy. As tin was present to the extent of only 0.002 per cent, its effect was neglected. The method used to determine boron in the steels shown in Table 9* was developed by Galen Porter, Vincent Napoleon, and Thomas R. Cunningham, of the Union Carbide and Carbon Research Laboratories, Inc., and is a modification of J. Naftel's procedure for boron in soils

Jan 1, 1944

By H. F. Yancey, M. R. Geer, Franklin T. Davis

Coke with low phosphorus content is required by some of the electrometallurgical and chemical plants recently attracted to the Pacific Northwest by the hydroelectric power available from Bonneville and Grand Coulee dams. Shipping such coke into the area from eastern points involves a high freight charge, and during wartime consumes precious rail and ship-bottom space, so it is highly desirable to produce coke from the coking coals of Washington to meet the requirements of these industries. Although coke has been made from Washington coals since 1884, little has been known about their phosphorus contents or about the extent to which phosphorus could be reduced by cleaning, An investigation was undertaken, therefore, to determine the manner in which phosphorus occurs in the coking coals of Washington and its amenability to removal by ordinary coal-washing methods. Previous Work Phosphorus is a deleterious element in coke used for numerous metallurgical processes, including the production of pig iron, yet comparatively little published information is available on the occurrence and elimination of phosphorus in any of the coals of this country. A variation from 0.009 to 0.062 per cent phosphorus in various horizons of the Pittsburgh bed in the Connellsville region of Pennsylania has been reported,' and a reduction in phosphorus content from 0.020 per cent in the raw coal to 0.018 per cent in the washed coal was obtained in washing coal from the same bed in the Pittsburgh area;2 the latter figures represent average analyses for a year's operation of the washery on about 800,000 tons of coal. A reduction in phosphorus content from 0.018 to 0.011 per cent in washing coal from the Pittsburgh bed at another washery was observed, and the same report provides data on the phosphorus reduction obtained by separating 10 other coals on a bath of 1.35 specific gravity.3 European investigators have been especially active in correlating phosphorus content with petrographic analysis; fusain and durain generally contain the highest percentage of phosphorus, but this relationship is not universal.4 Some of these investigators have found that phosphorus is removed in the coal-washing process,5 but others have observed that the clean coal contained as much or even more phosphorus than the raw coal.'

Jan 1, 1944

By Felix B. Shay

The Agua Fria mine is in eastern Honduras at Lat. 140" 06' N., Long. 86" 36' W. Danli, the seat of the local municipal government, is the nearest town. The property is approximately 44 miles east of Tegucigalpa, the terminus of a truck road from the Pacific coast. The mine lies at an altitude of 3300 ft. with surrounding elevations as high as 6000 feet. For 20 years the oxidized croppings of the Agua Fria vein had been worked intermittently when in 1927 an attempt was made to open the property. A shaft was sunk 300 ft. and considerable ore was blocked out, but before a mill could be installed financial difficulties arose and the mine reverted to the original owners. Erle Y. Halliburton, of Los Angeles, purchased the property in 1934. At that time a careful consideration of all factors involved showed that air transport was the only practical method of moving the equipment and machinery necessary to commence production. The other alternative was by muleback, which required sectionalizing all equipment to a maximum load of 200 lb., and during the rainy season this type of freighting was subject to serious delays. It was decided to purchase a trimotor Ford powered by three Pratt and Whitney Wasp B motors developing 400 hp. each. There were several reasons for the choice: (1) this type of plane was available at a reasonable price, owing to its replacement by faster models on most of the airlines in the United States; (2) the ship was capable of carrying a pay load of 3000 Ib. over the required distance; (3) since this airplane had been widely used there would be no difficulty in securing competent personnel or in purchasing spare parts. It was necessary to rebuild the plane for cargo servicc. The windows were removed and the fuselage was entirely covered. A hatch was cut in the top of the fuselage to receive heavy crane loads and pieces of freight that were too large or too long to go through the rear door. The seats were removed and the interior of the plane was lined with Duralumin sheets. A heavy-duty landing gear was installed and the floor was reinforced. The nearest site for an airport was two miles north of the mine. The necessary grading was done by a small track-type tractor with a wheeled grader, which was brought in overland. Six weeks was required for bring-

Jan 1, 1940

By M. King Hubbert

THE growth of human knowledge is an evolutionary process. Historically our separate sciences came into existence as people became interested in various apparently unrelated domains of phenomena, and in this manner we acquired the sciences of physics, chemistry, astronomy, biology and geology. As various of these sciences became established, cognizance of them came to be taken by the universities and in this manner there arose the traditional departments of physics, astronomy, chemistry, biology and geology of our American universities. As there was no particular rationality in the boundaries separating the various sciences, in the university departments the jurisdiction of each has assumed quite arbitrary limits. In the domain of earth phenomena the first science to grow up was that of geology, which arose originally from the activities of the collectors science dealing with directly observable terrestrial phenomena for which elementary rational explanations were offered. The traditional treatment of phenomena by the science of geology has rarely been with more than an elementary regard for the fact that these phenomena were also phenomena of physics and chemistry. Since the latter part of the nineteenth century, a new approach to terrestrial phenomena has been emerging and becoming of so great a significance that it can no longer be ignored. This approach has been made by people trained primarily in the sciences of physics and chemistry, who have investigated terrestrial phenomena as constituting phenomena of their respective sciences. In this manner we have acquired the so-called "borderland sciences" of geophysics, the physics of the earth, and of geochemistry, the chemistry of the earth. Neither of these fields is new, having arisen chiefly at the hands of European investigators during the latter part of the nineteenth century. The European universities have long since given official recognition at least to geophysics, by the establishment of departments or institutes of geophysics, which are on a par with the university departments of the other sciences.

Jan 1, 1938