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By William Metcalf

ONE of the first questions that naturally occurs to one who handles steel is," Why does steel harden ?" To answer this question the chemist and physicist have devoted much thought and experiment, and while they have enriched our store of knowledge of the nature and composition of steel, it cannot be said that they have yet solved the problem involved in its hardening. In this communication I desire to direct attention to a line of investigation yet new, in the hope that it may receive the attention of those who have the time and ability to pursue it. I refer to magnetism. There are so many parallels between the action of magnetism on iron and steel and their behavior under different processes of manipulation that it would seem as if there must be some connection between the forces at work in the different cases, if, indeed, there be not an identity of force in all of these cases. Magnetism, as we know it, may be merely the visible manifestation of forces, which may serve as a guide to lead us to an exact knowledge of the structure, the strains, and the resistances with which we have to deal in iron and steel. If a magnet be brought close to a pile of iron filings, the little pieces of iron will fly to the magnet and attach themselves to it, with their longer axes lying in the direction of the force. If molten cast iron be poured into an iron mould,-a chill,-the iron upon crystallizing will form needlelike crystals, with their long axes normal to the surfaces of the mould. If the iron is at the proper temperature and the quantity small, compared to the mass of the mould, the whole of it will be chilled, or set, in' the hard needlelike crystals

Jan 1, 1881

By Renato G. Bautista, Gary A. Beetner, Anthony L. Frey

The flow of material in a pump mixer-settler extractor was studied photographically and visually by injecting dye into the equipment and following its advance through the various sections of the equipment. Volumetric measure of the flow was obtained from analysis of the photographs. The organic portion of the settling chamber, the fluid surrounding the pump mixer, and the pump mixer itself were found to be operating in plug flow. The aqueous portion of the settling chamber was found to be partially mixed. Significant dynamic effect was noted due to density changes in the feed streams. The quantitative and qualitative observations made of the flow within a single stage should be of value in predicting the flow patterns in all similar equipment, including opaque and liquid metal solvent extraction systems.

Jan 1, 1973

By C. E. Birchenall, F. N. Rhines, L. A. Hughes

A. J. Shaler—I should like to congratulate the authors on the presentation of this paper, which we have been awaiting a long time. The view they have taken of the sintering process, namely that voids are comparable to particles of a second phase capable of dissolving to a slight extent in the metal phase, is an interesting but dangerous one. Pines has given a first-order solution of the problem and Has predicted a decrease in the concentration of pores near the surface. The authors of the present paper have experimentally demonstrated the second-order effects, that is, the diffusion of the space phase between voids of different sizes, and also the movement of atoms from highly curved parts of a void to less curved regions of the same void. I have recently calculated the rate of vapor-phase transport within odd-shaped pores in copper at 850 °C and found that probably at that temperature volume flow is the more rapid shape-changing mechanism. The authors of the present paper have found that at 1000°C, vapor-phase transport is dominant. There is no disagreement here, I think. The dominant phenomenon can easily be different' in different temperature ranges and with different pore shapes: I used a cylinder going to a sphere, not a tricuspid going to a "triple cuspidor." But there is some danger in the other art of the explanation, that is, in the study of the diffusion of vacancies from a pore to its neighbors and to the outside. A vacancy is very different in dimension from an atom. When it moves, it carries a field of elastic strain. This has to be taken into account. A concentration gradient of vacancies can cause them to diffuse. But in the absence of such a gradient, they can be made to diffuse by a field of stress. What happens in some of our experiments, and it is most noticeable in the shrinkage of synthetic cylindrical pores, like the tubes we have been working with, may be broken down into the following steps. (1) The presence of a surface establishes a vacancy concentration gradient, as Dr. Kuczynski and the present authors have shown. (2) Vacancies then diffuse in order to decrease this gradient. (3) In so doing, they cause an elastic field to be built up in such a direction as to oppose the diffusion, so that it slows down until it reaches a steady-state rate. (4) The steady-state flow is due to the fact that the surface tension acting on curved surfaces applies a stress to the system which itself mechanically causes vacancy diffusion. What I have said is that the diffusive types of flow of the authors and of Dr. Kuczynski are transient phenomena which soon stop if the pores are large. We are then left with a mechanical problem only, and our researches have not yet disclosed just what the mechanism of flow is; it may be a slip process, or it may take place by a vacancy diffusion of the type Nabarro has de-

Jan 1, 1951

By R. W. Fenn, H. A. Lepper, W. R. Hibbard

A. J. Shaler—I should like to congratulate the authors on the presentation of this paper, which we have been awaiting a long time. The view they have taken of the sintering process, namely that voids are comparable to particles of a second phase capable of dissolving to a slight extent in the metal phase, is an interesting but dangerous one. Pines has given a first-order solution of the problem and Has predicted a decrease in the concentration of pores near the surface. The authors of the present paper have experimentally demonstrated the second-order effects, that is, the diffusion of the space phase between voids of different sizes, and also the movement of atoms from highly curved parts of a void to less curved regions of the same void. I have recently calculated the rate of vapor-phase transport within odd-shaped pores in copper at 850 °C and found that probably at that temperature volume flow is the more rapid shape-changing mechanism. The authors of the present paper have found that at 1000°C, vapor-phase transport is dominant. There is no disagreement here, I think. The dominant phenomenon can easily be different in different temperature ranges and with different pore shapes: I used a cylinder going to a sphere, not a tricuspid going to a "triple cuspidor." But there is some danger in the other art of the explanation, that is, in the study of the diffusion of vacancies from a pore to its neighbors and to the outside. A vacancy is very different in dimension from an atom. When it moves, it carries a field of elastic strain. This has to be taken into account. A concentration gradient of vacancies can cause them to diffuse. But in the absence of such a gradient, they can be made to diffuse by a field of stress. What happens in some of our experiments, and it is most noticeable in the shrinkage of synthetic cylindrical pores, like the tubes we have been working with, may be broken down into the following steps. (1) The presence of a surface establishes a vacancy concentration gradient, as Dr. Kuczynski and the present authors have shown. (2) Vacancies then diffuse in order to decrease this gradient. (3) In so doing, they cause an elastic field to be built up in such a direction as to oppose the diffusion, so that it slows down until it reaches a steady-state rate. (4) The steady-state flow is due to the fact that the surface tension acting on curved surfaces applies a stress to the system which itself mechanically causes vacancy diffusion. What I have said is that the diffusive types of flow of the authors and of Dr. Kuczynski are transient phenomena which soon stop if the pores are large. We are then left with a mechanical problem only, and our researches have not yet disclosed just what the mechanism of flow is; it may be a slip process, or it may take place by a vacancy diffusion of the type Nabarro has de-

Jan 1, 1951

By Alexandre Pourcel

The perusal of Mr. Willard P. Ward's " Notes on the Behavior of Manganese to Carbon," presented at the Washington meeting of the Institute in February, 1882, has suggested further reflections on the same general topic, and has led to the preparation of the present paper. The same observation that Mr. Ward has put on record in his "Notes" was also made by myself at about the same time (in August, 1875), and under almost the same conditions. From a blast-furnace that was very hot, as was the furnace mentioned by Mr. Ward, I obtained a pig-iron containing about fifteen per cent. of manganese, gray in color, and very tough. It could be pulverized, but could not be cut with the chisel. I analyzed this iron and found that it contained, as I had suspected,a large amount of silicon. From this fact I drew the conclusion that the silicon had deprived the manganese of its power of dissolving carbon, since the latter, instead of occurring in the pig in combillation, appeared as graphitic carbon. I thus saw reproduced on a large scale, and demonstrated in a visible way, the property that Colonel Caron, a French scientist, had discovered in silicon,—the property of obstructing the process of hardening in steels by keeping the carbon in the graphitic condition. An attentive study of the conditions under which the phenomenon observed by Mr. Ward takes place led me to go back to operations of synthesis, and to make as I wanted them pig-irons containing varying quantities of silicon, manganese, and carbon. An iron, thus prepared, was intended to serve me as a chemical reagent in the production of steels cast without blow-holes, such as my lamented friend, Mr. A. L. Holley, has introduced and made known to the United States. What I needed in order to make very soft steels, cast without blow-holes, was an iron which, when it was added to the bath of steel, introduced into the bath a sufficient amount of silicon and of

Jan 1, 1883

By Donald Barton

THE theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A = K MM/R2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical discussions and calculations in regard to gravity, that other body usually is taken as a unit of mass: in the C. G. S. system, a body of one gram in mass. GRAVITY AND LEVEL SURFACES Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration. In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm./sec 2) and less commonly merely as centimeter-gram-second units (C. G. S.). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. In most cases, it is very nearly, but not quite, perpendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as "the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it commonly is very nearly, but not quite, a straight line.

Jan 1, 1928

By P. S. Kotval

THE nominal composition of "hconel" alloy 718 is 53 pct Ni-19 pct Cr-19 pct Fe-3 pct Mo-5 pct Cb-0.8 pct Ti-0.6 pct A1-0.05 pct C. The nature of the fine strengthening phase in this alloy has been open to debate. iseelstein' has identified the strengthening phase in the matrix of "Inconel" alloy 718 as a colum-bium-rich fcc y' precipitate. Wagner and Hall2 have noted that the metastable y' precipitate overages to an orthorhombic Ni3Cb precipitate which manifests itself as an acicular phase. These authors thus clarify Kaufman and Palty's earlier suggestion3 that the strengthening phase is orthorhombic NisCb. Wagner and Hall's review also reports work by cometto4 which suggests that the fine strengthening phase is not fcc / but bct with a Ni3V type structure and based on the Ni3Cb composition. Kir man and warringtons have shown by analysis of electron diffraction patterns that the metastable strengthening phase in a 55 pct Ni-15 pct 0-25 pct Fe-5 pct Cb alloy is bct and based on the Ni3Cb composition. Raymond~ has provided electron diffraction evidence which indicates that "y'" in "Inconel" alloy 718 is bct in structure. This note presents unambiguous data on the structure of the strengthening phase in "Inconel" alloy 718* ihe samples of this alloy were provided by courtesy of the ASTM task group on phase identification in 'superalloys. after prolonged aging. The electron diffraction patterns presented show that strengthening phase is not y' but bct as was proposed by cometto,' supported by Raymond,~ and identified by Kirman and warringtons in a similar system. Fig. 1 shows a selected-area diffraction pattern taken from a thin foil of "Inconel" alloy 718. The sample had received a final aging treatment of 1118 hr at 1200°F to precipitate the strengthening phase in the matrix. Fig. 2 is a schematic representation of the features in the diffraction pattern. The matrix orientation is (0i2)~,, as is shown by the indexed zone in Fig. 3. Figs. 4, 5, and 6 illustrate that the pattern, Fig. 1, is composed of three bct zones, viz., (0i4), (2i0), and (i01), respectively. These three zones correspond, respectively, to the alignment of the c axis of the bct unit cell with the [001], [loo], and [OlO] directions of the fcc matrix and serve to illustrate the fully coherent relationship of the precipitate structure with the matrix. The streaking of certain reflections is also consistent with the above orientation relationship. The interpretation of the diffraction effects presented here shows the metastable strengthening precipitate in "Inconel" 718 alloy to be bct in structure and demonstrates that it is not an ordered fcc y' phase.

Jan 1, 1969

By Robert E. Hoffman, John B. Hudson

The self-diffusion coefficient of pure lead has been measured at five pressures between atmospheric and 40 kb. over a temperature range of about 150°C near the melting point at each pressure. Measurements were made using a radiotracer technique, samples being sectioned electrochemically after the diffusion anneal to determine the diffusion penetration curve. Pressure was applied in a "belt" type pressure device similar to that used by Hall et al., in the diamond synthesis. The self-diffusion coefficient, D, can be represented by an equation of the form at constant pressure, and an equation of the format constant temperature. An apparent correlation between the effects of pressure on self-diffusion and on the melting point of the material observed by Nachtrieb et al., at pressures below 10 kb. was found to be only approximate as measurements are carried to higher pressures. OVER the course of the past 30 years a large number of studies1-' of the rate of atom movements in solid metals have been carried out. These studies have in general been aimed at increasing the understanding of the detailed atomic process by which atom movements in metals can take place. The largest portion of these studies consisted of measurements of the self-diffusion coefficient, D, as a function of temperature. From such studies con- siderable information regarding the energetics of the motive process has been deduced. Recently such measurements have been extended to the pressure dimension. However, the existing work in this area is scanty and has in the past been limited to the pressures attainable in oil or gas bombs—i.e., up to about 10 kilobars (kb). In the present work, the self-diffusion behavior of pure lead has been investigated using the "belt" type high-pressure apparatus designed by Hall7 over a pressure range from atmospheric to 40 kb at temperatures extending over about a 150°C range close to the melting point at each pressure.

Jan 1, 1962

By Donald C. Barton

The theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A = KMRm2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical discussions and calculations,in regard to gravity, that other body usually is taken as a unit of mass: in the C:. C:. S. system, a body of one gram in mass. Gravity and Level Surfaces Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm. /sec.2) and less commonly lrierely as centimeter-gram-second units (c. g. s). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. In most cases, it is very nearly, but not quite, perpendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as ('the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it comrrlonly is very nearly, but not quite, a straight line.

Jan 1, 1929

By Franklin H. Allison

The influence of cobalt and nickel on the properties of steel might be readily expected to be very similar. The two elements occupy close and somewhat unusual positions in the periodic table, their chemical behavior and compounds are so completely analogous and their various physical properties, including the ferro-magnetic characteristic, show such 3 remarkable correspondence, that there is no doubt of a strong resemblance existing between these two metals. However, the variety of properties that are obtained from steel is due largely to the fact that the element iron possesses allotropic forms. Alloying elements that affect these allot ropic forms, or alter the nature of the allotropic changes, exert a profound influence on the resulting steel. In the case of nickel and cobalt, although these elements are very similar chemically and physically, it is found that they differ distinctly in their individual effects on the critical points of iron. Both nickel and cobalt form a series of homogeneous solid solutions with iron at temperatures above 1500" F. The difference in their behavior does not occur until changes begin to take place in the solid state below this temperature. An inspection of the respective thermal equilibrium diagrams at the lower temperatures makes the opposite effects of nickel and cobalt clearly evident. Effect of Nickel and Cobalt in Binary Alloys with Iron The binary diagram of iron-nickel has been investigated by a number of workers. The lower temperature portion in Fig. 1 is reconstructed from the data of D. and H, Hanson.1 The diagram of iron-cobalt, shown in Fig. 2, is taken from the work of Ruer and Kaneko.2 Masumoto3 has recently discovered a lower critical point in cobalt and this has been added to the diagram. In both diagrams the space lattice structures as determined by Andrews4 have been included. It is interesting to note

Jan 1, 1927

By M. King Hubbert

THE theme of this paper is that one of the greatest retarding factors in progress of geologic science is the inadequate training given to students of geology in schools and universities. Students of geology are still taught as though geology were an independent, sovereign domain of science. Consequently, only in exceptional cases do geology students acquire more than the most elementary introductory college courses in mathematics, physics and chemistry, and frequently not even so much. Furthermore, students with such training receive Ph. D. degrees in geology, and often they become professors of geology in our universities. The phenomena of geology are also phenomena of physics, of astron-omy, of chemistry, and to a lesser extent, of biology; and to properly deal with them a knowledge of mathematics, physics and chemistry considerably beyond the elementary level is necessary. Already many of the physical and chemical problems of the earth, such as earthquakes, gravity, hydrology, meteorology, and the physical chemistry of rocks and minerals, are being attacked with considerable success by the employment of the methods of physics and chemistry, and being written almost exclusively in the language of advanced mathematical physics and chemistry. Geophysics is not just a "borderland field" between two sciences; on the contrary, it is the process whereby the knowledge and techniques of the more fundamental science, physics, are borrowed and employed in solving the problems of the more dependent science-geology. Geo-physics therefore embraces a large part of the two sciences taken together. The institution of work in geophysics, in its true sense, in depart-ments of geology would go far toward correcting the present inadequate training of students of geology and bringing the members of that profes-sion more uniformly abreast of the advances being made in earth science by people whose training has been primarily in the fundamental sciences of physics and chemistry rather than in geology. If something of this sort is not done, the geological profession may contemplate being left farther and farther behind as the scientific procession moves onward.

Jan 1, 1938

By R. B. Sosman

INTRODUCTION WE have shown in the preceding paper that practically all natural oxides of iron contain a determinable percentage of ferrous iron, and in many cases the percentage approaches that in magnetite itself. Some of these oxides are true homogeneous solid solutions. Others are not homogeneous, and can be separated magnetically into fractions. The nature and cause of this inhomogeneity in certain special cases form the subject of the present paper. MAGNETIC FRACTIONATION OF OXIDES OF IRON The magnetic fractionation of a sample of oxide can be conveniently carried out by powdering the material very fine, and exposing it at various distances from the poles of an electromagnet. The magnet that we used was specially designed 1 to give a strong field together with a steep gradient outside of the poles. It is set in a frame, with the pole pieces directed downward. A glass plate can be adjusted at various distances beneath the poles. If the fine iron oxide powder is placed just beneath the glass plate, successive portions of the powder are picked up by the magnetic attraction and are caught against the glass plate, the most magnetic portions being taken up at the greatest distance from the poles. Some natural oxides can thus be separated into several-fractious of different magnetic susceptibilities. Among other natural iron oxides, we examined the powder obtained by crushing some crystals of hematite from Elba.2 We found that

Jan 6, 1917

By R. T. Carter

THE phase behavior of a number of binary systems consisting of paraffin hydro-carbons has been determined in recent years. In addition, the composition of the coexisting phases of mixtures of crude oil and natural gas has been investigated.1 However, the latter study did not include information concerning the influence of the concentration of a component upon its distribution between two coexisting phases. Owing to the paucity of such information it was considered desirable to investigate in some detail the composition of the co-existing phases in the methane-propane-n-pentane system throughout the greater part of the two-phase region at a tempera-ture of 100°F. Information of this nature also permits the establishment of the critical behavior of this ternary system.

Jan 1, 1940

By Frank Robertson Van Horn

In June, 1911, the writer spent a few days in studying the economic geology of the vicinity of Park City. During this rather hurried visit a number of specimens of ore were collected, which have since been examind. The results of these investigations show that bournonite (PbCu-SbSa) is present in the ores in greater or less quantity. This fact has never before been reported, as far as can be learned. The failure to recognize this mineral is due to its similarity to tetrahedrite, with which it has probably been confused during a long period of years. Jamesonite (Pb2sb2s6) has been reported from the region in a rather doubtful manner, but the writer has seen it in notable amounts from several mines, and can offer the first analysis of this mineral from the district. Calamine (HzZn2SiO5) was found at one mine and has never been ecognized and reported from the district. Geogbaphy and Geology Park City, Utah, is located at an elevation of about 7,000 ft. above sea level on the eastern slope of the Wasatch mountains. It is situated approximately 25 miles southeast of Salt Lake City. ' The geology and ore deposits have been described in detail by Bout well and Woolsey.' The mines visited are situated south-southeast from the town. The Silver King Coalition mine is located in Woodside gulch about 1 mile southeast of Park City, at an altitude of about 8,100 ft. The other mines visited were the Daly West and Quincy, which are in Empire canyon about 2 miles sontheast of the town, at elevations of 8,300 to 8,500 ft. respectively. The Daly Judge tunnel goes into the mountain from Empire canyon about 1 mile south of the city, at an altitude of 7,700ft.

Jan 1, 1915

By Richard Ageton

SALT bodies in the form of rolls, horses (sometimes called horsebacks), folds, wants and pinches1 have been encountered while driving entries and mining out rooms during the development of the potash mines in New Mexico. Superficially these sporadic salt occurrences appear to be much alike, but closer examination reveals individual characteristics, and after four years of observation it seems possible to divide them into three general groups that may tentatively be called "depositional," "erosional," and "structural." The data collected are not yet sufficient to permit forecasts of their probable location, so that the annoyance of having to mine salt instead of potash could be avoided or lessened. However, the information so far available appears to throw some light on the occurrence of the sylvinite2 bed now being mined, and it is as a progress report that the writer presents the results of his observations. The mines of the United States Potash Co. and the Potash Company of America are about 20 miles northeast of Carlsbad, in Eddy County, N. M. They are on the southwestern flank of the Permian salt basin, which underlies western Texas, Oklahoma and Kansas, south-central Nebraska, southeastern Colorado and eastern New Mexico. The cuttings from many oil wells and the cores from the potash tests drilled in this basin indicate that this salt series approached its greatest thick-ness (about 4000 ft.) in the southeastern part of New Mexico and the adjoining portions of Texas, and that the most advanced stages of

Jan 1, 1936

By H. M. St. John

Like every present-day manufacturer, the brass foundryman is faced with the necessity of reducing the cost of his finished product without impairing its appearance or quality. He must use every economy that the progress of art and science puts at his disposal and should also be alert to profit by any peculiarity in his own situation or the nature of his product that may give him an exceptional advantage. Much can be accomplished by the adoption of labor-saving equipment and improved methods of melting, molding and handling. Control of pouring temperature, study of defective castings and their causes, laboratory control of molding sand and core mixtures, the use of less expensive alloys, all contribute to the desired end. Assuming that the composition of the alloy is already as inexpensive as the character of the casting will permit, still further savings can be made by the intelligent purchase and utilization of the metals needed to produce the desired analysis. Functions of Secondary and Virgin Metals in Casting Brass It is no longer a general assumption among foundrymen that quality castings must be made from an "all virgin" mix. If suitable secondary metals can be obtained more cheaply it is wasteful to use any larger proportion of virgin metal than is required to produce castings of the desired properties. To follow such a course, however, imposes upon the foundryman a heavier obligation than was formerly the case, to make sure by test and inspection that his castings really are of the desired quality. So long as he used the most expensive grades of metal and his melting practice was reasonably correct he was not obliged to give much thought to the quality of the metal in the castings. If he is to use secondary metals he must, in order to retain the confidence of his customer, examine these metals very carefully before use, exercise scrupulous control over his melting and pouring conditions and examine his castings closely. These statements apply more particularly to the jobbing foundry. The foundry department in a manufacturing plant is in a somewhat

Jan 1, 1930

Albert SauveuR, South Chicago, Ill. (communication to the Secretary): Mr. Howe remarks (nuns., xxiii., 656) that, running through my paper, there is a tacit assumption that there is a constant and known relation between the coarseness of the grain of steel and its quality. The above assumption was not made tacitly. On the contrary, it is based upon the very experiments embodied in my paper. Indeed, most of those experiments were undertaken with that end in view, i.e., to ascertain the existence of such a relation. Mr. Howe calls attention to the fact that of two pieces of manganese-steel, originally from the same bar, the coarser-grained showed the greater strength and ductility. This refers to the fracture of the pieces; whereas, I have considered the micro-structure only, independent of the fracture; and I do not think that a coarse fracture

Jan 1, 1895

By H. C. Howarth

This paper gives observations on ground movement and subsidence resulting from pillar drawing in the Lick Run section of Montour No. 10 mine of the Pittsburgh Coal Co. adjacent to solid coal owned by the U. S. Bureau of Mines at its Experimental mine in Snowden Township, Allegheny County, Pennsylvania. The investigation was planned by George S. Rice, chief mining engineer of the Bureau, who arranged the necessary cooperation with Dr. L. E. Young, vice president of the Pittsburgh Coal Co. Engineers of that company placed permanent monuments on the surface to establish the boundaries of the coal owned by the Bureau and to furnish fixed points to which all levels were referred. Engineers of the Experimental mine staff then covered the ground under observation with a checkerwork of monuments made of oak pegs set into the ground at 50-ft. intervals in two directions at right angles to each other. The level of these pegs was determined first from Dec. 16 to 30, 1929; again from May 25 to June 5, 1930, and finally from July 7 to 15, 1931. Observations were then discontinued because work had been stopped temporarily in this part on Montour 10 mine. General Conditions Fig. 1 is a plan of the part of the area under observation with which this paper deals. The mine is developed on a room and pillar system known locally as half advancing and half retreating. As Nos. 35 and 36 butt entries were advanced, rooms were driven from No. 36 and drawing of the room pillars followed their completion. When the entries reached the boundary, rooms were started from No. 35 butt beginning at that point, and all remaining pillars were drawn as rapidly as possible. The rib lines of Jan. 9 and June 13, 1930, were surveyed a week to 10 days after the first and second sets of levels were run, and there was some advance in that period. The rib line of July 15, 1931, agrees in time

Jan 1, 1934

By W. E. Forsythe

WHEN measuring ordinary temperatures, the instrument is generally placed in very close contact with the body the temperature of which is desired. However, if the temperature of the source is continually raised, a point is soon reached where no known substance will, in general, remain constant in any of its temperature-measuring properties if placed in direct contact with the source. Also, it is occasionally necessary to measure the temperature of a source that 'is so small or so situated that it would be very hard to bring the measuring instrument into direct contact with the source. When these conditions exist, advantage is taken of the well-known fact that all bodies, when at sufficiently high temperatures, send out radiation in amounts readily measurable. This radiation has been found to be related to the temperature. The temperatures of very hot bodies have probably always been judged by the color, or the brightness, of the light given off. With practice, one can estimate probably within 50° to 100° C. of the correct value. However, if judgment is left to the eye alone, very much larger errors are sometimes made, due to

Jan 9, 1919

By M. N. Short, I. A. Ettlinger

M. N. Short,? Washington, D. C., and I. A. Ettlinger, New York', N. Y. (New York Meeting. February, 1926) The Pioneer mining district, better known as the Superior district, from its principal town, is located in Pinal County in south-central Arizona about 80 miles east of Phoenix and 22 miles west of Miami. The region embraces a, confused series of mountain ranges of moderate height but precipitous slopes, between which lie irregular valleys filled with alluvial detritus. The average elevation is about 2800 ft. in the valleys and the summits of the ranges reach 2000 ft. above this. Superior is situated on the north bank of Queen Creek where it emerges from one of those ranges into a more or less basin-shaped valley. The drainage of Queen Creek is to the southwest and the flood waters spread out and lose themselves in the desert northeast of Florence, the county seat of Pinal County. The Magma copper mine (Fig. 1) is the only producer in the district. Although discovered in 1875, its production has been important only

Jan 1, 1927