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By H. Winkelmann

The author, who himself has worked inn the field with various types of torsion balances, expresses in the article his experience with the recently marketed Haff-Torsion-Balance. The advantages of practical work with Haff?s s torsion balance as compared with other types are mentioned. In spite of low weight and corresponding small dimensions (Model M = 23.5 kg., Model Al = 11.5 kg.) the sensitiveness is not less than that in the largest instruments. It is at 1.10-9, which is proved by calculations. A comparison with the corresponding values of other types of torsion balances (Eötvös, Askania, Gepege) is given. The mechanical features of the instrument are briefly described, and the balance is illustrated by a, cross section of it. -- W. Ayvazoglou. DETERMINATION OF THE ELEMENTS OF THE MAGNETIC AND GRAVITATIONAL FIELDS INDUCED BY AN INFINITELY LONG HOMOGENEOUS CYLINDER By G. A. Gamburzeff Gerlands Beiträge zur Geophysik, Band 19, Heft 2/3 Leipzig, 1928, pp. 210-230. The present work is a. contribution to the quastion of the reason for the magnetic and gravitational anomalies in the government of Kursk (Russia).

Jan 1, 1929

By Paul M. Tyler

The technology of clay and the manufacture of ceramic products therefrom, and also the clay resources of most of the individual States, are already covered by a voluminous literature. The present resume touches these matters only briefly; its purpose is essentially to bring together in small compass certain of the elementary factors affecting the potential commercial value of a clay deposit. In its preparation the author made extensive use of the annual chapters on Clay in Mineral Resources of the United States and in the two annual issues of the Minerals. Yearbook that succeeded them. For careful review and constructive criticism of the manuscript, the author is indebted to Hewitt Wilson. GENERAL DESCRIPTION The term ?clay? includes a great variety of substances that may differ widely in chemical mineralogical and physical properties. No two clays are exactly alike. All of them however, have the prominent characteristic of becoming more or less plastic when wet. Nearly all of the useful clays can be molded into articles, will hold their shape while being dried, and can be converted into a hard, rocklike substance by heat. Clay may, and in fact usually does, consist of a number of minerals among the commonest of which are kaolinite, quartz, feldspar, iron oxides, mica, bauxite, calcite, and manganese oxides. Organic matter is often present. Pure kaolinite, which has the formula A1203. 2 SiO2. 2H2O, is ordinarily, considered to be the parent "clay substance," butt most clays contain other hydrated mixtures of alumina and silica (aluminosilicic acids) along with indefinite amounts of sand and other nonessential minerals3/ Even, this so-called inert matter affects the plasticity, drying shrinkage, ease of drying, and final density, and at high temperatures may react chemically with the clay substance.

Jan 1, 1929

By James S. Wroth

The Act of Congress approved June 25, 1926 (Public Act 424, 69th Congress), authorized joint investigations by the U. S. Geological Survey and the U. S. Bureau of Mines to determine "the location, extent, and mode of occurrence of potash deposits in the United States." The particular deposits selected for exploration were the extensive rock-salt formations underlying large areas in western Texas and southeastern New Mexico, from which potash salts had been identified in the cuttings and sludges from oil wells drilled with cable tools. The evidence of these sludge samples was qualitative only and beyond definitely proving the presence of potash salts in the salt beds, gave little clue to the possible size, richness, or extent of the potash occurrences.

Jan 1, 1929

By Roy H. Poston

This paper sets forth the mode of ore occurrence, characteristics of ore and country rocks, methods of exploration, development, and. ore extraction, and the costs of underground operation at No. 8 mine of the St. Louis Smelting and Refining Works of the National Lead Co. located near the southern extremity of the Southeast Missouri lead district. The author acknowledges the assistance of E. T. Campbell, geologist, in the preparation of the paragraphs on the geology of the ores. HISTORY The first record of mining in St. Francois County, Mo., concerns more or less shallow semisurface "diggings" which were worked about the year 174-2. In 1864, however, the discovery of the disseminated deposits, the present source of lead, was made on property near the town of Bone Terre. Winslow has estimated the lead-ore production in this county prior to 1869 to be 59,526 tons.3

Jan 1, 1929

By Robert W. Thomas

This paper describing the mining practices at the Ray mines at Ray, Arizona, is one of a series being prepared by the Bureau of Mines on mining practices, method and costs in the various mining districts of the United States. At the present time (1929) all mineral Production of the Ray district comes from the Ray Mines of the Nevada Consolidated Copper Co. The ore body is being worked from two shafts, designated as No. 1 and No. 2. An undercut block-caving method of mining is used, variations of which are employed to fit different conditions. The present method has been developed by making improvements as experience was gained or when conditions changed. Refinements in practice are continually being made. The Ray mine was the first in the Southwest to use a caving system of mining on a large scale.

Jan 1, 1929

By Fred W. Snow

This paper describing the mining practices at the Magma mine, Superior, Ariz., is one of a series being prepared by the Bureau of Mines on mining prac¬tices, methods, and costs in the various mining districts in the United States. At present (1929) practically all the mineral production in the Superior district is from the Magma mine of the Magma Cooper Co. The ore is mined for its copper but contains associated silver and gold. Both direct smelting ore and ore of concentrating grade are produced. The mining methods now in use at the Magma mine were adopted or developed as knowledge was gained of the physical condition of the ore bodies and the inclosing formations; the wall rock is soft and crushed and the ore is relatively hard. In general, existing methods have been adapted to fit local conditions, but some of the mining practices used were originated at this mine. Most of the ore is mined by a combination of rill stopes and pillar stopes. The pillars are extracted by underhand mining.

Jan 1, 1929

By B. Numerov

A numerical proceeding of corrections with respect to topography is worked out for places near the station and a graphical one for the remote parts of the terrain. The description is clear and very detailed. The numerical proceeding is very similar to that of the Eötvös and Schweydar methods which are in use already. In both methods the levelling is accomplished in certain circles and fixed azimuths around the station. While, in using the Eötvös method, the height differences are directly inserted into the final formulas with regard to the foot of the instrument and in case of accurate formulas derived by Schweydar the height differences are calculated with respect to the center of gravity of the attachment, Numerov introduces functions A and B, the heights, of the terrain and of the center of gravity, which are to be inserted into the formulas.

Jan 1, 1929

By E. H. Denny

Colorado coal-mine fatalities, which have gradually decreased since 1914, have shown a marked decline since 1924. Data on coal-mine fatalities in Colorado published by the U. S. Bureau of Mines5 indicate that the deaths per thousand 300-day workers have decreased from 9.13 in 114 to 6.14 in 1926, and that the deaths per million tons produced have decreased from 9.18 in 1914 to 4.98 in 1926. Table 1 gives fatality rates in Colorado and in the United States from 1914 to 1926 inclusive. [ ]

Jan 1, 1929

By D. Harrington

The coal-mining industry of the United States finds difficulty not only in making ends meet financially but also in operating with anything like reasonable safety. The record to date has not been particularly good as to either finance or safety, but at least in some phases or safety there are indications of better times to come. During the fiscal year ending June 30, 1929, only 139 lives were lost in explosions in our mines as against 342 lost during the fiscal year ended June 30, 1928; this decrease in such fatalities is definitely a matter for satisfaction. During the fiscal year July 1, 1928, to June 30, 1929, the attention of the safety division of the U. S. Bureau of Mines was directed to 38 mine explosions in the United States. Two explosions were in non-coal mines, one in a semianthracite mine, two in anthracite mines, and 33 in bituminous mines. These were not all major explosions - that is, explosions in which five or more lives were lost; in some of the explosions no lives were lost, while in others fewer than five fatalities resulted. Table 1 gives data on the explosions, showing the number of mines using open or closed lights and the number of explosions with resulting deaths, by causes, for each State.

Jan 1, 1929

By Paul M. Linebarger

This paper is one of a series of digests of foreign mining legislation and court decisions prepared in advance of a general report relative to the rights of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws of Mexico has been pro oared from the best information available in Washington but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers, to whom it has been referred through the courtesy of the Department of State. INTRODUCTION Present-day Mexican mining legislation involves, not only the latest minim enactment (August 1, 1026), but many other enactments and regulations, principal among which are the Constitution, the Civil Code, the Code of Commerce, the Foreign Law, the Mining Tax Law, and. the Civil Jurisprudence of Mexico--the last-mentioned being based in Dart on Supreme Court decisions. Ere Mexican Federal Government is supreme in mining legislation because, among other reasons, a large part of the revenue of the Government must come from the fiscal control of the mines. All circulars, decrees, and rulings that affect the mines not only have their origin in the Central Government but are administered thereby. The Department of Industry, Commerce, and Labor is in control of all mines. Attention may here be called, however,

Jan 1, 1929

By A. D. Garman

This paper presents one of a series of digests of foreign mining legislation and court decisions which is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws of Guatemala has been prepared from the best available information in Washington, but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State.

Oct 1, 1929

By John W. Frey

This paper is one of a series of digests of foreign mining legislation and court decisions prepared in advance of a general report relative to the rights of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws of cw Zealand, as prepared by Dr. Frey the best available information in Washington, has been slightly amplified in accordance with suggestions transmitted through the courtesy of the Department of State by W. L. Lowrie, Consul General at Wellington.

Oct 1, 1929

By P. R. Bradley

This paper is one of a series , dealing with mining methods and costs , sponsored and published by the U. S. Bureau of Mines . Papers of this series are written by engineers and executives of mining companies , at the solicitation of the Bureau , and in accordance with an outline prepared by Bureau engineers , for the purpose of securing uniform presentation and conformable data . The property of the Alaska Juneau Gold Mining Co. is situated near the city of Juneau , Alaska , in what is known as the Harris mining district . Wholesale mining operations have been adopted on a large scale and 10,000 to 11,000 tons per day of gold- bearing ore are mined and sent to concentrators near Juneau . In addition to gold , the ore yields 0.6 ounce of silver and 13.0 pounds of lead to each ounce of gold recovered .

Oct 1, 1929

By John W. Frey

This paper presents one of a series of digests of foreign mining legislation and court decisions that is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries . This interpretation of the laws of Persia has been prepared from the best available information in Washington but is released subject to correction and amplification , if necessary , by the proper American diplomatic and consular officers , to whom it is being referred through the courtesy of the Department of State .

Nov 1, 1929

By Chas. F. Jackson

This paper is published as a progress report for the first half of 1929 on the study of wining methods and costs in the Eastern and Central States. Data obtained from 25 mines using open-stope methods are correlated and summarized. Some of these mines have been described in considerable detail in reports already published as Information Circulars. In addition to the published reports on individual mines, considerable data have been obtained from other mines which were visited and studied during the course of the investigation. Many of these mines will later be described in detail in separate papers, and when the field has been covered in this manner it is planned to issue a bulletin on open-stops methods of mining which will amplify the subject matter of the present paper. Definition of ?Open-Stops?. - The term "open-stopes" as employed by the Bureau of Mines is applied to all naturally supported stopes; that is, stopes in which the excavated ore is not replaced by support of an artificial nature other than preps or stulls and in which the ore or (and) capping are not caved during the active life of the stopes.

Jan 1, 1931

By A. U. Miller

The added hazards to mining incident to oil and gas wells penetrating the coal measures in proximity to mine workings , have long been recognized in those fields where the extraction of oil , gas , and coal , has been in progress for a number of years . The history of these fields is replete with stories of serious mine fires , explosions , and miraculous escapes from both fires and explosions due to either oil or gas finding its way into the mine workings through the strata , or by mining into an unknown or uncharted and abandoned oil or gas well that had not been properly plugged . The Director of the Bureau of Mines , in response to numerous requests from coal operators and oil and gas operators , called a meeting in 1913 to discuss necessary precationary measures to take when drilling oil or gas wells through workable coal beds and to try, if possible . to formulate a set of regulations that might serve as a guide to those persons preparing regulations covering the drilling of oil and gas wells in the various coal producing States . This meeting was attended by representatives of the coal , oil , and gas industries , State geologists , State mine inspectors , and representatives of the Bureau of Mines . A committee was appointed to prepare a set of regulations , which was later published as U.S.Bureau of Mines Technical Paper 53 ; the discussions and results of the meeting werepublished as U. S. Bureau of Mines Bulletin 65 . Later , the American Institute of Mining and Metallurgical Engineers appointed a committee to draft a model law for the use of the legislature of any State concerned . This committee made its report on April 27 , 1928 . Several of the coal mining States now have more or less comprehensive regulations governing the drilling of oil or gas wells through workable coal beds , others have regulations that are inadequate , while some have no regulations . The State of West Virginia recently enacted a law containing reg lations which are the result of a comprehensive and careful study of the problem .

Nov 1, 1929

By R. R. Sayers

The added hazards to mining incident to oil and gas wells penetrating the coal measures in proximity to mine workings , have long been recognized in those fields where the extraction of oil , gas , and coal , has been in progress for a number of years . The history of these fields is replete with stories of serious mine fires , explosions , and miraculous escapes from both fires and explosions due to either oil or gas finding its way into the mine workings through the strata , or by mining into an unknown or uncharted and abandoned oil or gas well that had not been properly plugged . The Director of the Bureau of Mines , in response to numerous requests from coal operators and oil and gas operators , called a meeting in 1913 to discuss necessary precationary measures to take when drilling oil or gas wells through workable coal beds and to try , if possible . to formulate a set of regulations that might serve as a guide to those persons preparing regulations covering the drilling of oil and gas wells in the various coal producing States . This meeting was attended by representatives of the coal , oil , and gas industries , State geologists , State mine inspectors , and representatives of the Bureau of Mines . A committee was appointed to prepare a set of regulations , which was later published as U.S.Bureau of Mines Technical Paper 53 ; the discussions and results of the meeting werepublished as U. S. Bureau of Mines Bulletin 65 . Later , the American Institute of Mining and Metallurgical Engineers appointed a committee to draft a model law for the use of the legislature of any State concerned . This committee made its report on April 27 , 1928 . Several of the coal mining States now have more or less comprehensive regulations governing the drilling of oil or gas wells through workable coal beds , others have regulations that are inadequate , while some have no regulations . The State of West Virginia recently enacted a law containing reg lations which are the result of a comprehensive and careful study of the problem .

Nov 1, 1929

By John W. Frey

This paper presents one of a series of digests of foreign mining legis- lation and court decisions which is being prepared in advance of a general re- port relative to the rights of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws of Portugal, prepared from the best available information in Washington, has been slightly amplified in accordance with suggestions trans- mitted through the courtesy of the Department of State by Fred Morris Dearing, American Minister at Lisbon.

Nov 1, 1929

By MINE SAFETY BOARD

Mining men and State officials in their efforts to make mining safer are confronted from time to time with various complicated questions . In recent years these questions have tended to increase with the use of mechanical appliances . Twenty- five years ago electricity had hardly been used in mines . To - day there is practically no other means of transmitting energy employed in American mines , except in metal mines where compressed air is used for drilling and small portable hoists . In coal mines there has been a great increase in mechanization and a tendency to concentrate the mining operation , which has resulted in attendant difficulties of ventilation and intensified the danger of coal - dust in bituminous and subbituminous mines . The answers to the questions which arise are not always obvious , as is shown by the fact that even able , experienced men differ in their opinions of the best way to overcome a particular mining hazard . The difficulty of solving the problems is also demonstrated by the varying provisions in mine safety rules , both in official regulations and in the rules of those mining companies who are endeavoring to do more than follow the letter of the law . Such differences of opinion on the best way of meeting a difficult situation are often found within the same mining organization , and so it has been in the Bureau of Mines .

Nov 1, 1929

By John W. Frey

This paper presents one of a series of digests of foreign mining legis- lation and court decisions, which is being prepared in advance of a general re- port relative to the rights of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws governing the Portuguese overseas possessions, prepared from the best avail- able information in Washington, has been slightly amplified in accordance with suggestions transmitted through the courtesy of the Department of State by Fred Morris Dearing, American Minister at Lisbon.

Nov 1, 1929