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By H. K. Shearer

There were no important developments in the oil and gas industry in South Arkansas during 1935. Oil production, totaling 11,138,340 bbl., continued the decline that has been normal since 1925, but the decline from 1934 was only 278,600 bbl., or 2.5 per cent. The principal decline was in the Smackover field, while only the Champagnolle and Garland City fields showed notable increases. More wells were drilled than in any recent year, with a total of 123 completions. There were 44 oil wells, with a total reported initial daily production of 10,013 bbl., or an average of 227 bbl. per well. Two small gas wells were completed in Union County, where the gas is used locally for pumping and field operations. There were 77 dry holes, of which 28 were in or near oil fields and 49 were wildcats. Active drilling oper-at'ions declined from 65 at the beginning of 1935 to 41 at the end. Most of the drilling was done during the first part of the year, espr-chially (luring the flurry caused by the discovery late in 1934 of the "Taylor" sand production in the Champagnolle field, but the producing area was soon outlined. In November, 1935, the J. E. Crosbie, Inc., NO. 1 Sullivant in sec. 12, 17s. 14W., producing 560 bbl. per day at 3175 ft., opened a new sand lens in the eastern part of the field. The Camden "oil field," discovered in the last week of 1934, remained a one-well field, although four offset tests were drilled, besides a number of others in the immediate vicinity. Several interesting deep tests were drilled during the year, which added a great deal to the general knowledge of the subsurface formations and the structure of south Arkansas, but were not particularly encouraging as to prospects for the very deep production. First, the H. L. Hunt, No. 15 E. F. Gregory well in sec. 10, 17S., 14\W., in the Champagnolle field, was drilled to a depth of 6911 ft. It pene-trated red beds for 2982 ft., from 2943 to 5925 ft., mostly if riot entirely of Lower Cretaceous age. There was some anhydrite in the last 135 ft. of red beds. This was followed by 890 ft. of limestone, probahly Permian, and the rock salt was struck at 6815 ft. The salt is now generally conceded to be of Permian age. Finding salt in this well strongly indicates

Jan 1, 1936

By Liang Yin-Huai

In Fuxin Coal Mines, there are more than 20 million tons of coal buried under seasonal streams. The coal seams are mostly shallow. We have mined more then 50 mining blocks distributed in 5 coal mines. Their natural conditions are different, and the consequences are also more or less different. However, no stream-water-inrush accidents under regular mining conditions are the same. There were 3 exceptions. They were caused by unexpected roof caving which made valleys or alluvia subside as funnel-like cavities and let in inrush of stream flow. The key to our success in mining shallow under-stream coal seams, according to our analysis, is that valleys or alluvia subside gently and basically evenly with contractible tension fissures and that fissures both in valleys or alluvia and in rock seams are blocked up or sealed by cohesive deposits either from alluvia or rock. This paper treats: (1) some typical illustrations of mining shallow coal seams of different occurrences under streams of different sizes, flowing capacities and valley structures, (2) observations of the height of caved and fissured zones and subsidence of valleys or alluvia, (3) observations of underground water flow before, during, and after mining and the fluctuation with respect to stream flow, (4) observations and analyses of blocking up of fissures caused by mining, and (5) feasibility of mining shallow under-river coal seams.

Jan 1, 1990

Australia today is one of the leading countries in the fields associated with the mineral industry, an industry which accounts for over 50% of overseas income and revenue to government. This is no accident. In order to be competitive in what was recog- nised very early in the country's history as a highly profitable busi- ness, the Australian mineral industry (mining, extractive and refining metallurgy) has traditionally been very innovation con- scious, a characteristic which has been evident from the begin- ning of the industry or very nearly so: Australia's geographic isolation and the dispersion of the mineral industry over wide distances made an exchange of ideas difficult and often impossible. One needs only to look at the inaugural address given by Sir Henry Ayers, the first president of the then Australasian Insti- tute of Mining Engineers, in Adelaide on 4th April, 1892 (1) "There is probably no other pursuit which depends more on its productive development and profitable results than in the extent and application of the scientific and mechanical knowledge possessed and exercised by its manager." and "Having in view the value of the mining industry of Austral- asians, they should be urged to apply their best skill with all the scientific and mechanical knowledge obtainable to its future development."

Jan 1, 1988

By J. E. Lawver, R. R. Beebe, J. L. Wright

This paper describes a separation coefficient Ks useful as a "measure of goodness" to be used in factorial and response surface methodology. The use and limitations of the separation coefficient is discussed, and a computer program for calculating the coefficient is presented (in Fortran). The application of the coefficient is illustrated in terms of electro-dynamic separation of Mesabi semitaconites. Present Mesabi wash ores and gravity concentrates with an iron to silica ratio of only 5 or 6 to 1 are no longer readily salable, for the steel industry now demands concentrates with an iron to silica ratio of at least 10 to 1 and a structure comparable to pellets. THE ELECTRODYNAMIC-FLOTATION PROCESS Wash ores and gravity concentrates consist largely of hematite, goethite, and quartz. Several methods of beneficiation are being tested at the University of Minnesota Mines Experiment Station with a view to improving the salability of these materials. A process that looks particularly promising from an economic view is the combination electrodynamic-flotation process shown in Fig. 1. This process is designed to upgrade gravity concentrates to a 5% silica content and to provide fines — from the flotation circuit —to permit agglomeration. Although electrodynamic concentration of specularite is an established and well-understood process, the electrodynamic concentration of Mesabi goethite-hematite gravity concentrates presents interesting and enigmatic problems. The gravity concentrates are by no means assemblages of clean, free mineral particles. Instead, the concentrates to be retreated consist of a great variety of middlings. More or less complete liberation would require grinding to minus 325 mesh, at which size only flotation could be expected to function, and even then grades and especially recoveries would not be satisfactory. A close examination of the gravity concentrates shows that grinding to 100% minus 48 mesh will produce a product which is approximately 70 weight % plus 325 mesh (see Fig. 1). The remaining 30 weight % can be deslimed and floated by conventional methods, but the resulting iron concentrate is

Jan 1, 1964

By Steven J. Page, Robert A. Jankowski, John A. Organiscak

Quartz dust is one of the most significant ongoing health concerns in coal mining today. Since initial verification of this health risk in coal mines by the Mine Safety and Health Administration (MSHA) during the early 1980’s, the Bureau of Mines has conducted numerous studies in underground mines to identify the sources of quartz dust and its fundamental characteristics. The most significant underground quartz dust source was found to be the continuous miner excavating rock. The percentage of quartz was also found to be higher in the smaller size fractions of the dust when significant amounts of rock was mined by the continuous miner. Furthermore, the quartz content in the continuous miner return remained fairly consistent at greater distances from the face. Another important factor speculated to affect quartz dust generation and its size characteristics is the morphology of the quartz bearing rock. The quartz content of dust between mines had notable differences with respect to the differences between kaolinite content in the dust. Low kaolinite content was associated with higher quartz content and increased size segregation of quartz into smaller dust particles, indicating that the free silica bonding matrix in the rock is most likely another factor responsible for quartz dust produced through mechanical comminution.

Jan 1, 1991

By Eduardo Martinez Baca

Although Mexico has always been justly considered by the whole world essentially a mining country, this reputation is due principally to the richness of the deposits which have been worked. In reality, the majority of the States have been little

Jan 1, 1902

By D. Bessinger, N. Rughubir

Exxaro Sands KZN produces?among other heavy mineral products?high titania slag, which is used as feedstock to the pigment industry. The titania slag is produced from the smelting of ilmenite in two 36 MW DC furnaces. In this smelting process carbon monoxide gas is produced. This gas is cooled, scrubbed and washed to remove entrained dust. This paper provides details on the gas cleaning plant system and the chemistry, mineralogy and size distribution of the particulate material contained in the off-gas stream. Characterization of the dust shows that is consists mainly of ilmenite, but with relatively high levels of SiO2and MnO. Smelting of the dust in a 500 kW DC furnace was carried out to investigate the potential for recovering valuable elements from the dust.

Jan 1, 2007

By G J. I dos Santos

The risk assessment of mining projects is directly related to the possible failure in estimating, and as estimates are made from sampling results, this activity should be done in a judicious and planned manner, to avoid surprises at the start of project operation. Pierre Gy’s (1995) sampling theory addresses the issue of sample representativeness and indicates that only the certainty that the sampling procedure was performed with quality may result in samples being recognised as representative. To validate the representativeness of samples from sampling boreholes selected for studies of mineral processing, the team of geology resource assessment of VALE has proposed a methodology based on the use of statistical analysis tools, which in addition to considering the spatial distribution of these samples in deposit, considers whether they are representative of the populations studied, allowing the geologist to make a quick analysis of sample representativeness.

Jul 11, 2011

The Institute makes liberal provision for inclusion of engineering students through individual Student Associate membership. Such members pay $2 per year, receive MINING AND METALLURGY, may purchase Technical Publications at reduced rates, have the privilege of attending all meetings and are furnished a distinctive badge in the form of a watch fob. Provision is also made for the affiliation of organized student societies in recognized schools of engineering chemistry, geology and related sciences. In order to qualify for affiliation it is not necessary that all members of the society become Student Associates since the individual members of the society are not listed as members of the Institute However, a large majority of the members of many of the societies are also Student Associate Members of the Institute. Among the things that the Institute does for the affiliated societies are the following: (a) A copy of each issue of MINING AND METALLURGY is furnished to the society; (b) Reports of the meetings and activities of the society are reported in MINING AND METALLURGY; (c) Assistance is given by the Institute in obtaining speakers for the meetings of the society; (d) The name of the society and of its officers is listed in the annual Directory and other publications of the Institute; and (e) Members of the society are given the use of the Engineering Societies Employment Service. Student organizations, desiring to be recognized as affiliated student societies of the Institute, should make application to the Secretary, giving particulars as to the nature of their organization, of their membership, and their officers. The accom¬panying list on page 24 gives the names of the affiliated student societies, their presi¬dents and their secretaries, as of April 17, 1931.

Jan 1, 1923

By Walter Miller

During the second year of America's active ia in the war the inain objectives of the petroleum-refining industry were again to provide the four most important product needs for war: 100-octane aviation gasoline, toluene for T.N.T. production, high-quality lubricating oils for the needs of aviation and the armed forces, and petroleum chemicals for synthetic rubber manufacture. All other materials supplied by the petroleum industry took an inferior priority ranking, depending on the degree of essentiality. To accomplish the above objectives the industry initiated and carried on a building program during 1942 and 1943 which will put those two years down in petroleum-refining history as the greatest construction years of all time, a record which will hold for decades to come. Led by an estimated total of $ 900,000,000 going into 100-octane and contributory plant investment, it is easy to picture a total of two billion dollars and more going into additional refining-industry plant investment during 1942 and 1943, most of it privately paid for, but a substantial part covered by R.F.C. Government money financing. Some of the new plants will not be completed until 1944, but a large proportion of the program was finished and put into operation, adding substantially to the output of the four principal products during 1943- lne most important and spectacuiar activity of the refining industry is of course the 100-octane gasoline program necessitated by the fact that nearly 90 per cent of the requirements of the United Nations is being furnished by the United States. Recent P.A.W. figures mention $goo,-ooo,ooo as the cost of the construction looking to increasing the output of this all-important munition. Thirty-four major plants have been completed, 11 of them during the last quarter of the year. Thirty-eight more will be completed and put into operation during the first four or five months of 1944. Twenty-two additional plants authorized during 1943 are already well under way and scheduled for production late in 1944. Early in 1942 the aim was to treble the capacity for making 100-octane gasoline then existing; later, plans were to make it five times as great, to match the increased warplane building program; and toward the end of the year the sights had been set at a still higher but unannounced target, representing six to seven times the early 1942 figure. Comparative figures issued at the end of 1943 enable one to guess a program by the middle of 1944 of eight to nine times the former production, with an ultimate production in 1944 of eleven or more times the early 1942 output. It became obvious in 1943 that building of new units would be materially slowed because of delay in getting construction materials and that they would reach operation at considerably later dates than

Jan 1, 1944

By Walter Miller

During the second year of America's active ia in the war the inain objectives of the petroleum-refining industry were again to provide the four most important product needs for war: 100-octane aviation gasoline, toluene for T.N.T. production, high-quality lubricating oils for the needs of aviation and the armed forces, and petroleum chemicals for synthetic rubber manufacture. All other materials supplied by the petroleum industry took an inferior priority ranking, depending on the degree of essentiality. To accomplish the above objectives the industry initiated and carried on a building program during 1942 and 1943 which will put those two years down in petroleum-refining history as the greatest construction years of all time, a record which will hold for decades to come. Led by an estimated total of $ 900,000,000 going into 100-octane and contributory plant investment, it is easy to picture a total of two billion dollars and more going into additional refining-industry plant investment during 1942 and 1943, most of it privately paid for, but a substantial part covered by R.F.C. Government money financing. Some of the new plants will not be completed until 1944, but a large proportion of the program was finished and put into operation, adding substantially to the output of the four principal products during 1943- lne most important and spectacuiar activity of the refining industry is of course the 100-octane gasoline program necessitated by the fact that nearly 90 per cent of the requirements of the United Nations is being furnished by the United States. Recent P.A.W. figures mention $goo,-ooo,ooo as the cost of the construction looking to increasing the output of this all-important munition. Thirty-four major plants have been completed, 11 of them during the last quarter of the year. Thirty-eight more will be completed and put into operation during the first four or five months of 1944. Twenty-two additional plants authorized during 1943 are already well under way and scheduled for production late in 1944. Early in 1942 the aim was to treble the capacity for making 100-octane gasoline then existing; later, plans were to make it five times as great, to match the increased warplane building program; and toward the end of the year the sights had been set at a still higher but unannounced target, representing six to seven times the early 1942 figure. Comparative figures issued at the end of 1943 enable one to guess a program by the middle of 1944 of eight to nine times the former production, with an ultimate production in 1944 of eleven or more times the early 1942 output. It became obvious in 1943 that building of new units would be materially slowed because of delay in getting construction materials and that they would reach operation at considerably later dates than

Jan 1, 1944

By M. Connell, S. Bedrossian

Alkali cracking followed by chloride-based leaching is one of the prominent methods for rare earth element processing. Regeneration of the leach lixiviant, namely hydrochloric acid, is a critical operation in the process. A number of different process routes are available for recovery of hydrochloric acid from chloride solutions. The objective of this paper is to discuss various recovery routes and analyze the impact of several input variables on the variable operating cost.

Jan 1, 2014

By M Byrne, P Newman, M Lindqvist

SomincorÆs Neves Corvo Mine, one of the largest copper producers in Europe, is currently constructing a paste backfill plant in order to replace cemented rockfill in its bench and fill stopes and possibly replace hydraulic sandfill in the drift and fill stopes. A 250 m flow loop was constructed at the mine and the flow properties of various paste blends were investigated. Cycloned tailings and total tailings were both pumped successfully as pastes and were also combined with waste rock for additional testing. The pressure losses in 102 mm and 154 mm diameter pipeline were recorded at flowrates up to 60 m3/hr and are presented at slumps from 120 mm to 250 mm. The data showed the sensitivity of paste mixtures to slight changes in consistency, confirming the need for accurate control during paste production and distribution. The flow results clearly showed the different paste behaviour between cycloned and total tailings pastes and the change in properties at low and high slumps. In addition to pressure loss data, strength testing was done on 38 mm and 82 mm diameter samples. Further strength testing is ongoing at the mine using fly ash as a supplement to cement, reducing the overall binder cost. Preliminary engineering for the underground distribution system is briefly discussed, with reference to the siting of the plant. The Neves Corvo Mine is particularly shallow and alternative methods to pumping were sought in order to ensure sufficient hydraulic head for underground distribution. The comparison of options had to take into account the capital and operating costs, the operation of the plant and the impact on the future expansion of paste fill utilisation at Neves Corvo.

Jan 1, 1998

By William L. Langdon

PRELIMINARY COMMENTS Recent years have been difficult for the mining industry, as reported in the most recently published Minerals Yearbook (Volume III), the estimated value of world crude mineral production has been generally declining since an historical peak in 1979 (16).* The costs of mineral extraction have, however, been rising rapidly. Individual project costs are, in general, exceeding the growth rate of mining companies, while operating and technical risks continue to increase (16). Risks resulting from currency flotation and political actions in the host country are also on the increase. Labor difficulties (such as those experienced by Phelps Dodge) and the Reagan Administration's recent rejection of a proposal by the International Trade Commission for higher tariffs and/or quotas on copper imports have also contributed to the mining industry's difficulties. The net result of these factors has been financial difficulties for mining companies with respect to paying for their current financial obligations as well as trouble finding new financing. It may be that one of the main factors in determining the future of the mining industry will be centered upon capital structure, i.e. how its assets are financed. Historical Perspective on Capital Structure In The Mining Industry As discussed by Isreal Borenstein in (4) and Thomas Navin in (7), mining firms typically have used a financial model based upon high financial leverage, i.e. large amounts of debt relative to equity. This has been especially true for American firms developing orebodies discovered overseas. Problems sometimes occurred for those who were forced to commit themselves to completion guarantees in order to obtain bank loans. Mines under these circumstances must be brought into operation regardless of market conditions. Politicians in overseas countries also may use the high profits required by these high risk ventures to argue for nationalization of mines. Coupled with the frequent use of high leverage, mining companies traditionally have paid out a higher percentage of earnings in the form of dividends than manufacturing firms. This is significant, in that such funds paid out in dividends are not available for other uses. Hence, a greater reliance upon debt and/or additional stock issues than would ordinarily be the case for manufacturing firms. Thomas Navin has stated in (7), that the theory behind the high dividend payout was that, "most mining investors thought of themselves as investing in a wasting asset, one that would gradually deplete over time until it ultimately became valueless." Investors, therefore, required a receipt, in the form of dividends, of a percentage of current earnings and a return on original capital. This view of reality, apparently, has not changed in some quarters, even though modern mine management ordinarily replaces depleted mines with new ones. It may be that this practice of high dividend payout coupled with relatively high financial leverage should be reexamined. Current capital structure theory could prove interesting and useful for those concerned with current conditions. Capital structure patterns and related practices in this industry are not, in many cases, congruent with those thought by some to be theoretically optimal. Prelude to Capital Structure Discussion With a few notable exceptions (such as the Guggenheims and Anaconda's chief operating,. officer in 1971) mining companies' chief executives and boards of directors have not been persons with financial backgrounds. This, one could conjecture, might have accounted for the relatively nonsophisticated nature of capital structures of mining companies. In order to appreciate the possibilities with respect to alternative influence on a firm's performance, one must be acquainted with the basics of financial theory. This paper is an attempt to familiarize the reader with (1) capital structure in general, (2) the usual components of this structure, (3) the general theory behind the use of financial leverage, and

Jan 1, 1985

By Christine Hansen

?Kiss my Asteroid? Unofficial Title Human life is tied to minerals It?s worth noting that: The living human body consumes minerals. The minerals we take in multivitamins show the close linkage between human beings and mineral resources. Unlike tourism or specialized manufacturing, a human being could not live without mineral consumption. Minerals and their consumption is a tangible part of human life.

May 1, 2013

By Tarrant GC

Cement and resin encapsulated tendons are widely used in the stabilisation of mine roadways. One of the main factors in controlling the efficiency of the reinforcement is the ability of the tendon to generate load in response to rock deformation. The analysis of field data from instrumented reinforcing tendons complimented with extensive laboratory investigations have more accurately defined the mechanisms by which load generation occurs. The role of reinforcing tendon profiles, hole geometry and encapsulation medium properties in controlling the reinforcement stiffness and capacity are discussed. The results of the investigation have implications in both the design of rock reinforcing systems and the optimisation of encapsulation mediums and tendons.

Jan 1, 1992

By Thomas J. Peters

The U.S. Bureau of Mines studied the 3,500-acre Winegar Hole study area, Idaho, a legislatively proposed (101st U.s. Congress) addition to the Winegar Hole Wilderness, Wyo.; it adjoins the western boundary of the Wilderness at the Idaho-Wyoming border, about 15 m; east of Ashton, Idaho. The study was part of an Idaho Land Assessment Program to provide minerals information for land-use decisions, and ensure domestic mineral supplies. The study area is an east-west elongated, wooded plateau south of Falls River. Although the area is covered with surficial glacial deposits, it is probably underlain by volcanic flows; light-colored and mafic flow rock were noted in sparse outcrop. No mines, prospects, mineralized areas, or mineral resources were found in the study area during a literature and field search. The only nearby prospects include geothermal and rock aggregate (volcanic cinder) sites, and several placer claims. Although the Winegar Hole study area lies within a region of potential geothermal resources, no evidence of geothermal activity was observed. Rock in the area does not split into flat slabs, which could be useful as dimension stone, and would require crushing to be used 8S aggregate. Alluvium (placer) samples contain less than SO.01 per cubic yard gold (at a $350 per oz price); alluvial deposits are too small to contain gold resources.

Jan 1, 1992

By d&apos, D. L. Guernsey, J. C. Entremont, John Chipman

The reaction of aluminum with oxygen in liquid iron has been studied at 1740° and 1910°C. Interaction coefficients are very much smaller than those previously published. The equilibrium constant falls within the approximate range of earlier experiments and calculations. It is now well established that the "deoxidation constant" for aluminum in liquid steel at normal steelmaking temperatures is extremely srnall. Thus at 1600 the product [% Al] is of the order of 10- 14. At this temperature, therefore, great experimental difficulties are encountered in any attempt to obtain a direct measure of the constant. If the aluminum content of the metal is high enough to permit accurate analytical determination, that of the oxygen is too low. If the oxygen content is high, the aluminum is below the limits of detection. Our best values of the constant have come, therefore, from indirect calculations or by extrapolation downward from observations at higher temperatures.. For their studies in the range 1695° to 1866°C, Gokcen and chipman' restricted their aluminum concentrations to less than 0.06 pct. Oxygen analyses were made by the vacuum fusion method which appears to be dependable at these low aluminum concentrations. Experimental results, even at the highest temperature employed, are extremely sensitive to small errors in the analysis of either element. The slight change in the equilibrium constant with aluminum and oxygen concentration was utilized in the calculation of interaction coefficients expressing the effect of aluminum on the activity coefficient of oxygen and the reciprocal effect of oxygen on the activity coefficient of aluminum. The range of concentration, however, was so limited that only a rough value for the interaction coefficient could be obtained. This value was much more negative than that found for any other pair of reactants. In view of the very limited range of concentration employed, the reported values have always been regarded as very questionable. A redetermination was the object of the work reported here. EXPERIMENTAL METHOD At high aluminum concentrations, the vacuum fusion method is susceptible to grave error due to absorption of gas by aluminum distilled from the sample. Since it was desirable to extend the study to at least as much as 1 pct Al, another method for analysis was sought. In steels containing more than a few hundredths of a percent aluminum and no other deoxidizing element, it is safe to assume that

Jan 1, 1963

By E Whiteman, L Reyneke, H Horsch

Heavy mineral sand deposits are a source for the economically important element titanium, which is contained in minerals such as ilmenite and rutile. In heavy mineral deposits ilmenite displays various degrees of alteration. Natural weathering of ilmenite involves the removal of Fe and thus results in an increase in the Ti-content. Minerals such as pseudorutile, ferropseudobrookite, anatase and the ill-defined mineral aggregate leucoxene, which consists mainly of various amounts of remnant ilmenite, pseudorutile, ferropseudobrookite and anatase, are typical replacement products of ilmenite. Ferropseudobrookite occurs as a recrystallised, optically and chemically distinct mineral phase. Textural relationships suggest a diversity of physicochemical conditions including weathering and metamorphism that led to the formation of complex mineral assemblages and textures. In the heavy minerals industry the alteration products of ilmenite are generally referred to as æaltered ilmeniteÆ and/or leucoxene. The distinction between æaltered ilmeniteÆ and leucoxene is not consequently defined and is very much dependent on economic factors and specific mining operations (ie determined by deposit specific mineral assemblages). Generally the term leucoxene is used in the heavy minerals industry as a collective description for ilmenite alteration products with TiO2-components ranging from 65 - 95 per cent. A detailed comparative mineralogical investigation including microscopic, SEM and QEMSCAN« techniques show that it is possible to identify and quantify the replacement products of ilmenite on a micron scale. QEMSCAN« generated particle maps were graphically compared with photomicrographs taken by applying reflective light microscopy. The resulting information can be integrated over the entire sample with respect to composition, absolute and relative mineral abundances, grain sizes, volumes, densities, textural relationships and liberation potentials. This provides a powerful tool for a first appraisal of the physicochemical behaviour of bulk samples and individual particles during metallurgical processing.

Jan 1, 2008

By Paul Weaver

OF the four papers that comprise this TECHNICAL PUBLICATION, three are case histories of individual geophysical prospects, subsequently tested by drilling. The bibliography of Dr. Barton's published scientific papers† includes investigaions in physiography and surface geological mapping, as well as his geophysical papers, and from this list it is to be observed that he early recognized the place of different types of geophysical prospecting methods in the search for geological structures of economic importance. Moreover, his viewpoint was not merely that the structures should be found, but that the geophysical data should be examined quantitatively to determine the geometry of the structures. In other words, that although these data are insufficient to deduce a unique form for the structure that caused the effects measured in the data, the engineering computations should be carried-out to give as much of a definite configuration to he structure as the data permitted, in order that the testing of the structures could be conducted in the most economical manner and with the idea that the experience so gained could be later incorporated in the study of structures subsequently found. Dr. Barton continually emphasized the quantitative use of geophysical observations, whereas at the time that he began his specialization in geophysics it was considered sufficient to use observations only qualitatively. He, more than any one else, was responsible for -the first volume on geophysical prospecting issued by the Institute in 1929, and his three articles in that volume stressed the quantitative use of geophysical prospecting. The fourth article in this present TECHNICAL PUBLICATION is a further contribution to this branch of geophysical interpretation, and is a supplement to the paper in the 1929 volume, "Calculations in the Interpretation of Observations with .the Eötvös Torsion Balance." From the successful' demonstration by Dr. Barton of the usefulness of quan-

Jan 1, 1944