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By Alfred E. Schwaneke

An improved maximum-bubble-pressure system using the Sugden twin-capillary method for measuring the surface tension and density of molten metals is described. Improvements include (1) internally ground capillary tips, (2) electronic pressure transducers, (3) micrometer adjustment of immersion depth for density measurements, (4) valuing arrangements to allow operation at other than atmospheric pressure, (5) temperature range to 1,100° C, and (6) recorder readout of pressures. Data for surface tension of mercury from 20° to 300° C are given.

Jan 1, 1970

By J. E. Tiffany, Z. C. Gaugler

This supplement has been prepared to furnish information on amendments to the regulations that were approved by acting secretary of the Interior on June 24, 1946, while this report was in the press. Page 14, item 2, and page 20, item 4, have been amended by the addition of the following footnote: "Pending the development of a satisfactory multiple-shot permissible blasting unit, a blasting unit of Type II, Class A, covered by Federal Specification WB 411, December 31, 1941 (with or without Amendment 2, June 16, 1945), may be used until Decem- ber 31, 1947. Should a satisfactory multiple-shot permissible unit be made available prior to that date, this interim approval may be terminated." Page 14, footnote / has been amended to read as follows: "The use of charges over 1-1/2 pounds and not exceeding 3 pounds is approved pending further investigation. The approval, which may be withdrawn at any time, expires December 31, 1947, unless renewed. For charges over 1-1/2 pounds, the following additional requirements must be observed: (1) Shot holes must be 6 feet or greater in length. (2) Explosives must be charged in a continuous train with no cartridges deliberately deformed or crushed, with all car- tridges in contact with each other, and with the end cartridges touching the rear of the hole and the stemming, respectively. (3) The permissible explosive must be one showing toxic gas omission that will place it in either Class A or Class B."

Jan 1, 1947

By D. Harrington, B. W. Dyer

"One of the products of the activities of the United States Chemical Warfare Service is a simple device and method for nearly instantaneous determination of small quantities of carbon monoxide in air. Since the war, this device has been diverted to commercial uses, and is now being marketed in connection with rapid determination of the comparatively small but dangerous quantities of CO, which may be found in garages, in sewers, about blast furnaces, etc. Also, it probably has a definite field of use in both coal and metal mines in connection with fires and explosions, as well as in confined places after firing of explosives) the latter applica-tion being of especial importance in metal mining.The device as marketed is readily portable, being small and light enough to carry in a coat pocket of medium size. In operation, a sample of the air mixture is drawn into a small rubber bulb, then forced through a small glass tube filled with certain chemicals upon which CO has the effect of changing the original color from gray or white to shades of green, the deepness of the green determining the percentage of CO in the air. A color scale is attached for purpose of comparison and determination of CO percentage. Only a few minutes are consumed in obtaining the result, all work being done on the ground.The exact effect of minute quantities (up to 1/10 of 1 percent) of CO on the human system is somewhat uncertain, and much research has been and is being done to obtain definite data on this point. It is, however, definitely known that in air containing more than 1/10 of 1 percent CO men doing hard work are quickly and seriously affected. As the gas is tasteless, colorless and odorless, methods of determining the presence of both small and large quantities have been of much importance. Technical Paper 11 of the U. S. Bureau of Mines gives much data as to effect of CO on mice and canaries. It was found that mice show very little distress until the CO content is about 0.20 percent, but quickly succumb when that percentage is exceeded; canaries are somewhat more susceptible; they quickly show distress in as little as 0.15 percent 00, and soon collapse when that percentage is exceeded."

Jan 1, 1921

"Minimizing Particle Contamination During Generation of Fresh Dust for Inhalation Studies J. Abraham, MS, Mechanical and Aerospace Engineering, West Virginia University, 1995Correlating Lung Crackle Using Holographic Interferometry Ali Afshari, MS, West Virginia University, 1989Effect of Bit Wear on Dust Generation Mudassar Ahmad, MS, West Virginia University, 1992 The Effect of Surfactants on Suppression of Non-Wettable Particles Ali Alaboyun, MS, Mineral Engineering, The Pennsylvania State University, 1989 Geochemical Characterization of Kerogens, Shales, and Coal Refuse Associated with Allegheny Formation of Cases of Northern West Virginia Dick Andre, MS, West Virginia University, 1987Size and Mass Characterization of Airborne Particulate Matter in Underground Coal Mines Using Diesel-Powered Equipment Indranil R. Bardhan, MEM Report, The Pennsylvania State University, 1992Size and Mass Characterization of Airborne Particulate Matter in Underground Coal Mines Using Diesel-Powered Equipment I. Bardhan, R. V. Ramani, and J.M. Mutmansky, Mining Engineering, The Pennsylvania State University, University Park, PA, Final Report to the U.S. Bureau of Mines, April, 1994Particle Concentrations in a Hazelton Inhalation Chamber Shahram Bavani, MS, West Virginia University, 1985Use and Potential of Lazer Holographic Interferometry and Subsidence Model- Study of an Underground Room and Pillar Mine Richard Begley, MS, West Virginia University, 1984Development of a Mechanistic Model for Prediction of Subsidence in a Longwall Mine Richard Begley, PhD, West Virginia University, 1990Redesign of Micro-Orifice Uniform Deposit Impactor Steve Behm, MS, University of Minnesota, 1991Evaluation of a Two-Phase Spray System for Dust Suppression B. Belle, MS, The Pennsylvania State University, 1996Evaluation of a Two-Phase Spray System for Dust Suppression B. Belle and R.-V. Ramani, The Pennsylvania State University, University Park, PA, Final Report, September 9, 1996A Fracture Mechanics Study of Crack Propagation Mechanism in Coal: The Mechanics of Fine Fragment Formation Z.T. Bieniawski and R. Karl Zipf, Jr., Mining Engineering Department, The Pennsylvania State University, University Park, PA. Final Report, October l, 1988A Mathematical Model for the Prediction of Ambient Dust Concentrations in Mine Atmospheres R. Bhaskar, MS, Mining Engineering and Operations Research, The Pennsylvania State University, 1984Spatial and Temporal Behavior of Dust in Mines-Theoretical and Experimental Studies –R. Bhaskar, PhD, Mining Engineering, The Pennsylvania State University, 1987"

Jan 1, 1998

By A. E. Raddatz

The Bureau of Mines has determined the electrochemical rate of anodic dissolution of vanadium metal in a VC12-VC13-NaC1 electrolyte at 860' C for the purpose of elucidating the reaction mechanism. Rate measurements were carried out with the help of specially designed equipment capable of continuously recording the weight loss experienced by a cylindrical vanadium anode immersed in the molten salt electrolyte while a constant current is maintained through it. The rate is expressed as a function of current density and VC13 concentration, and the reaction is interpreted in terms of an adsorption mechanism. Multiple regression analysis of the data gave the following rate equation: Rate x 104 (g.cm-2.sec-1) = -0.38 + 2.64 current density (amp-cm-2) + 0.69 log, (mole-percent VC13).

Jan 1, 1974

By Alice V. Peter

Meerschaum or sepiolite is employed principally in tobacco pipes and cigar and cigarette holders, although a few other uses of minor importance are Down. The unique value of a meerschaum pipe is derived from the owner's pleasure in watching the color deepen with smoking and in having the color "set" at the desired shade. The name "meerschaum" (German for "sea foam") is applied because the material, when pure and dry, will float on water. Owing to its resemblance to the porous, bonelike structure of the cuttlefish, or septa, it is also known as sepiolite. There are a few scattered deposits of meerschaum in. the United States which have yielded a small product ion, but the world's supply of the' material is obtained fined principally from Asia Minor, Meerschaum deposits near Eski-Shehir, Turkey, are said to have been worked 2,000 years ago, but commercial exploitation is a development of the last hundred years DESCRIPTION AND PROPERTIES Meerschaum is a hydrous magnesium silicate (H4Mg2Si3010) having the following theoretical analysis: Si02, 60.8 percent; MgO, 27.1 percent; H20, 12.1 percent. It is a soft. (H.2 - 2.5), fine-grained, earthy, white, gray, or yellow material. It is very light weight when pure (specific gravity, 1 to 2) and is highly absorbent. Because of its porosity the proportion of water present in the mineral is affected by the humidity'of the atmosphere. In a moist atmosphere the water content may be as much as 21.7 percent. Then wet the material is soft and somewhat plastic. When dried again it becomes lard and tough. The toughness is especially apparent in some forms that have a fibrous or leathery texture.

Jan 1, 1934

By Charles L. Kimbell

In 1990, the aggregate value of world international export trade in mineral commodities was estimated at more than $64 billion in current (1990) dollars, about 8.4% higher than that in 1989, but still 8.7% below the record high set in 1980. Table 8 provides a data series for the estimated value of world export trade in all mineral commodities from 1979 through 1990, as well as a breakdown of this total into fuel and nonfuel commodities. It is noteworthy that for this 1990 edition, trade data for the year of review were available in time for inclusion, whereas in previous editions, the latest available global trade data were for the year prior to the year of review. Hence, as regards trade, this edition of Minerals in the World Economy updates the 1989 edition by 2 years rather than by only 1. For this reason, it is appropriate to note that the 1989 global total value for inter-national export trade in mineral commodities was almost $596 billion, 11.1 % above the revised 1988 level of more than $536 billion, both figures expressed in current dollars for the appropriate year. Despite the considerable increase in the dollar value of mineral commodity exports, their share of total export merchandise trade declined to 19.1 % in 1990 from 19.7% in 1989. At 19.1%, this share was very near the recent year record low of 19.0% reached in 1988. The year 1990 was the fourth in a row in which the total value of world mineral commodity export trade increased.

Jan 1, 1993

By Donald P. Tuchman, Robert P. Vinson, Steven J. Page, Linda J. McWilliams, Gerald J. Joy, Steven E. Mischler, Jon C. Volkwein

The United States National Institute for Occupational Safety and Health, through an informal partnership with industry, labor, and the United States Mine Safety and Health Administration, has developed and tested a new instrument known as the Personal Dust Monitor (PDM). The new dust monitor is an integral part of the cap lamp that coal miners normally carry to work and provides continuous information about the concentration of respirable coal mine dust within the breathing zone of that individual. Previous laboratory testing demonstrated that there is a 95% con?dence that greater than 95% of individual PDM measurements fall within ±25% of reference measurements. The work presented in this paper focuses on the relationship between the PDM and respirable dust concentrations currently measured by a coal mine dust personal sampler unit utilizing a 10 mm Dorr Oliver nylon cyclone. The United Kingdom Mining Research Establishment instrument, used as the basis for coal mine respirable dust standards, had been designed speci?cally to match the United Kingdom British Medical Research Council (BMRC) criterion. The personal sampler is used with a 1.38 multiplier to convert readings to the BMRC criterion. A strati?ed random sampling design incorporating a proportionate allocation strategy was used to select a sample of mechanized mining units representative of all US underground coal mines. A sample of 180 mechanized mining units was chosen, representing approximately 20% of the mechanized mining units in production at the time the sample was selected. A total of 129 valid PDM/personal sampler dust sample sets were obtained. A weighted linear regression analysis of this data base shows that, in comparison with the personal sampler, the PDM requires a mass equivalency conversion multiplier of 1.05 [95% C.I. (1.03, 1.08)] when the small intercept term is removed from the analysis. Removal of the intercept term results in a personal sampler equivalent concentration increase of 2.9% at a PDM measurement of 2.0 mg m-3.

By John J. Sammarco, Janet S. Flynt

This report (Independent Functional Safety Assessment Guidance 7.0) is the last in a nine-part series of recommendations and guidance addressing the functional safety of processor-controlled mining equipment. It is part of a risk-based system safety process encompassing hardware, software, humans, and the operating environment for the equipment’s life cycle. Figure1 shows a safety framework containing these recommendations. The reports in this series address the various life cycle stages of inception, design, approval and certification, commissioning, operation, maintenance, and decommissioning. These recommendations were developed as a joint project between the National Institute for Occupational Safety and Health and the Mine Safety and Health Administration. They are intended for use by mining companies, original equipment manufacturers, and after-market suppliers to these mining companies. Users of these reports are expected to consider the set in total during the design cycle. • 1.0 Safety Introduction (Part 1).—This is an introductory report for the general mining industry. It provides basic system/software safety concepts, discusses the need for mining to address the functional safety of programmable electronics (PE), and includes the benefits of implementing a system/software safety program. • 2.1 System Safety (Part 2) and 2.2 Software Safety (Part 3).—These reports draw heavily from International Electrotechnical Commission (IEC) standard IEC 61508 [IEC 1998a,b,c,d,e,f,g]and other standards. The scope is “surface and underground safety-related mining systems employing embedded, networked, and nonnetworked programmable electronics.” System safety seeks to design safety into all phases of the entire system. Software is a subsystem; thus, software safety is a part of the system’s safety. • 3.0 Safety File (Part 4).—This report contains the documentation that demonstrates the level of safety built into the system and identifies limitations for the system’s use and operation. In essence, it is a “proof of safety” that the system and its operation meet the appropriate level of safety for the intended application. It starts from the beginning of the design, is maintained during the full life cycle of the system, and provides administrative support for the safety program of the full system. • 4.0 Safety Assessment (Part 5).—The independent assessment of the safety file is addressed. It establishes consistent methods to determine the completeness and suitability of safety evidence and justifications. This assessment could be conducted by an independent third party. • Safety Framework Guidance.—It is intended to supplement the safety framework reports with guidance providing users with additional information. The purpose is to assist users in applying the concepts presented. In other words, the safety framework is what needs to be done and the guidance is how it can be done. The guidance information reinforces the concepts, describes various methodologies that can be used, and gives examples and references. It also gives information on the benefits and drawbacks of various methodologies. The guidance reports are not intended to promote a single methodology or to be an exhaustive treatment of the subject material. They provide information and references so that the user can more intelligently choose and implement the appropriate methodologies given the user’s application and capabilities. The guidance reports comprise parts 6 through 9 of the series and are listed below: [< 5.1 System Safety Guidance (Part 6).—This guidance supplements 2.1 System Safety. < 5.2 Software Safety Guidance (Part 7).—This guidance supplements 2.2 Software Safety. < 6.0 Safety File Guidance (Part 8).—This guidance supplements 3.0 Safety File. < 7.0 Independent Functional Safety Assessment Guidance (Part 9).—This guidance supplements 4.0 Independent Functional Safety Assessment.] [ ]

Jan 4, 2006

By S. B. Levin

"INTRODUCTION An exposure of large beryl crystals in pegmatite on Beryl Mountain, in Sullivan County, N. H., was the basis for investigation by the Bureau of Mines to determine the extent of the beryl mineralization and to expose other parts of the same zone that were favorable for additional beryl-rich shoots. Testing by surface cuts, trenching, and tunneling was conducted by the Bureau of Mines from August to December 1943.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to the national security and economy. The Mining Division, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, O. C. Ralston, chief, analyzes samples and makes beneficiation tests. The field work was supervised by Paul M. Tyler, regional engineer, and John D. Bardill, district engineer. S. B, Levin was in direct charge of the project.LOCATION AND ACCESSIBILITYThe deposit is on the northeast slope of Beryl Mountain, 1 mile south of the village of South Acworth. The village, on State Highways 101 and 123a, is 12 miles northeast of Bellows Falls, Vt. The deposit is reached from South Acworth over a gravel-surfaced road and about 1,000 feet of good truck trail (fig. 1).The nearest railroad siding is at Cold River, on the Boston & Maine Railroad, where there is also a fairly modern, but now idle, feldspar mill."

Mar 1, 1948

By R. Karl Zipf

MULSIM/NL (multiple scams, nonlinear) is a three-dimensional boundary-element method (BEM) program developed at the U.S. Bureau of Mines for stress and displacement analysis of coal mines and thin metalliferous veins. It can analyze one to four parallel seams that can have any orientation with respect to the Earth&apos;s surface. Three main new features distinguish MULSIM/NL from its predecessors: (1) nonlinear material models, (2) multiple mining steps, and (3) energy release and strain energy computations. MULSIM/NL has six material models for the in-seam material: (1) linear elastic for coal, (2) strain softening, (3) elastic plastic, (4) bilinear hardening, (5) strain hardening, and (6) linear elastic for gob. Detailed checks show that numerical stress and displacement calculations compare well to known analytic solutions for simple problems. The total energy release calculated by MULSIM/NL is comprised of three basic terms: (1) strain energy release from the mined-out material, (2) linear kinetic energy release due to change in gravitational potential over the mined-out area, and (3) nonlinear kinetic energy release due to nonlinear materials in the total backfill and gob area. The strain energy release term is modified to account for nonlinear stress-strain behavior in the unmined materials. Comparisons of these numerical energy release rate calculations with known analytic solutions show excellent agreement.

Jan 1, 1992

By Herbert R. Appell

Urban refuse, cellulosic wastes, and sewage sludge have been converted to heavy oil by heating under pressure with carbon monoxide and steam. Conversions of the organic matter to oil, water, and gas have averaged near 90 percent at temperatures of 250° to 400° C and pressures of 1,500 to 5,000 psi. The yield of oil, based on the dry organic matter of the waste materials, is usually near 40 percent. This is the equivalent of more than 2 barrels of oil per ton of dry, ash-free waste material. The oil from urban refuse and cellulosic wastes has a sulfur content near 0.1 percent. This low sulfur content makes the oil from refuse a desirable source of fuel oil.

Jan 1, 1970

By BUREAU OF MINES

The Bureau of Mines, in its investigations of respiratory apparatus for use in mines and allied industries; tests equipment that is voluntarily submitted by manufacturers in accordance with published schedules of tests. These tests are designed to insure that the equipment has the minimum requirements for safety in use. Approval certificates are issued for apperatus that meets the bureau's specifications, and the manufacturer is permitted to mark his equiment with a seal showing that it has been approved as "Permissible." A complete list of per- missible self-contained oxygen breathing apparatus, gas masks, and hose masks tested prior to January 1, 1930, was published in Bureau of Mines Information Circular 62309. The present list includes all equipment tested and approved prior to July 1, 1930.

Sep 1, 1930

By M. B. Cooke, A. D. Bauer, E. W. Dean

The Bureau of Mines is collecting and analyzing representative samples of crude petroleum from all the producing fields in the United States , and the results are being published in a series of reports that are preliminary to the issue of a bulletin covering the entire survey . The bureau has recently completed a survey of crude oils from the Kansas district . In all 27 samples were collected and analyzed , under the direction of A. W. Ambrose , chief petroleum technologist of the Bureau. Valuable assistance was received through the cooperation of oil companies operating in the State , especially the Prairie Pipe Line Co. , and the Empire Pipe Line Co. The present report issued as Serial 2322 , on the Kansas crudes , forms the fifth of the series . Of the four previous papers , the first ( No. 2202 ) deals with crudes from the Eastern fields of the United States , the second ( No. 2235 ) with crudes from the Rocky Mountain district , the third ( No. 2290) gives additional data , cn viscosities and pour tests , for the crudes from these two fields , and the fourth ( No. 2293 ) covers the fields of northern Texas , northern Louisiana , and Arkansas . The details of the methods of collecting samples , making laboratory tests and interpreting results , have been discussed in these earlier reports . It has also been pointed out that the only adequate method of interpreting analyses of crude oils is to compare the individual reports with the analysis of some crude oil that is familiar to the operator . For this reason , no comprehensive discussion of the results of the Kansas survey is attempted, although some general statements may be made .

Feb 1, 1922

By C. C. Merrill

Columbium, tantalum, titanium, and zirconium are present in solid waste products generated by the chlorination of rutile used for production of titanium tetrachloride (TiC14). The columbium and tantalum were separated from titanium and zirconium by liquid-liquid extraction techniques using a secondary amine. Salts of these elements are in a leach liquor produced by water leaching of mineral waste from the chlorination of rutile. This waste, produced at the rate of approximately 50,000 tons per year, is about 40 wt pct water soluble. Leach liquors, separated by filtration, were further separated into a solid fraction and a liquid fraction by pressure hydrolysis, The solid fraction containing Cb, Ta, Ti, and Zr was dissolved in HC1-HF and used as a feed solution. Columbium and tantalum were removed from the organic extractant with 1 [N] HC1. A miniature 10-stage reactor showed that the columbium and tantalum present in solution could be separated with a continuous flow.

Jan 1, 1972

By E. D. Gardner

About five minutes after 3 o&apos;clock on Thanksgiving morning, November 24, 1927, smoke was discovered coming up No. 2 shaft of the Magma Copper Co.&apos;s mine at Superior, Pinal County, Arizona. Of the 49 men in the mine at the time, 42 were able to make their way to the outside unassisted, but 7 perished. Six bodies were recovered, and the seventh, that of an Apache Indian cage-tender at No. 2 shaft, is thought to be in the caved section between the 1,600 and 2,250 foot levels A second and independent fire broke, out in No. 1 shift about 2 a.m., November 27, burning .out the shaft timbers from the surface to the 200-foot level and destroying the surface fan and structures. About 20 men were underground fighting the fire in No. 2 shaft, but all were safely withdrawn, aril the fire in No. 1 haft was quickly controlled.

Jan 1, 1928

By P. R. Bremner

The United States is more than 90 pct dependent on imported bauxite a source for aluminum, but it has vast nonbauxitic aluminum resources, such as kaolinite, anorthosite, alunite, etc. As part of a program to devise processes for treating these resources, the Bureau of Mines investigated a bench-scale leaching process using hydrochloric acid (HC1) and fluoride to extract aluminum from Wyoming anorthosite. HC1 and fluoride-to-aluminum (F/Al) mole ratios were studied with respect to aluminum extraction for single-stage, cocurrent, and countercurrent leaching modes. Using 95 pct stoichiometric HC1 and a F/Al mole ratio of 0.27, 90 pct of the aluminum was extracted by countercurrent leaching. Single-stage leaching with the same amount of acid and fluoride extracted 48 pct of the aluminum. Three fluoride sources, CaF2, Na2SiF6, and H2SiF6, were used and gave similar results on aluminum extractions.

Jan 1, 1982

By D. J. MacDonald

The Bureau of Mines has carried out investigations on a method for producing zirconyl sulfate solution from zircon sand, comprising (1) reacting zircon sand with molten NaOH, (2) leaching the resultant fusion frit with water to remove sodium silicate and to convert sodium zircon-ate to hydrous zirconium oxide, and (3) leaching the hydrous zirconium oxide from unreacted sand with hot, dilute H2S04 to produce crude zirconyl sulfate solution. The following conditions were found to be suitable: reacting 0.6 kg of NaOH per kilogram of zircon sand for 10 min at 600° C; leaching the frit with 3 to 4 liters of water per kilogram of solids; leaching the residue with 5.1 liters of water and 1.25 liters of 98-pct H2S04 per kilogram of original solids for 10 min at 90° C; and filtering or decanting to recover unreacted zircon sand. A preliminary cost estimate is included.

Jan 1, 1982

By Kenneth L. Cashdollar

While underground coal technology has progressed over time, regulations on coal dust have not kept up ? the most recent rules are more than 80 years old. The National Institute for Occupational Safety and Health and the Mine Safety and Health Administration conducted a joint survey recently on coal particle ranges as measured in US coal mine samples. In underground coal mines, dust explosions are prevented by the addition of enough rock dust (usually limestone) to make the total dust mixture inert. The rock dust acts as a heat sink for the dispersed dust mixture by reducing the temperature below the value needed to propagate an explosion. Federal regulations require 65% in combustible content in intake airways and 80% incombustible content in return airways, where the coal dust is assumed to be finer in size. The regulations also require an additional 1% incombustible for each 0.1% methane in the ventilating air in intakes and 0.4% additional incombustible for each 0.1% methane in returns.

Jan 1, 2008

By John W. Adams

The present status of the National Bureau of Standards program is that many magnetic tapes of analog data have been recorded in four major mines. Each mine uses different types of equipment. In addition, some surface measurements of noise have been made at two additional mines. Two types of recordings have been made: (1) broadband measurements for spectral plots and (2) narrowband measurements for amplitude probability density (APD) plots. Only data from one mine (Robena #4) has been processed and was, presented at this workshop. The short-term goals are: (1) finish processing data from the other mines, (2) establish or reduce measurement system uncertainties, (3) put Robella report into final form for distribution, and (4) hold a review to determine what has been done, to distribute and to interpret the preliminary data, and to determine what still needs to be done. Long-term goals are: (1) complete final reports on each of the mine trips, (2) establish techniques for predicting noise in mines already visited and establish uncertainty bounds for these predictions, and (3) establish techniques for predicting noise in mines that have not been visited (but that use similar equipment to those visited) and also establish uncertainty bounds for these predictions. Specific factors or formats to be presented include: (A) For underground broadband measurements: 1. 300 Hz to 100 kHz spectral plots 2. 300 Hz to 384 kHz spectral plots 3. 300 Hz to 192 kHz spectral plots 4. 300 Hz to 6kHz (subject to change to 3 or 12 kHz) spectral plots (B) For surface broadband measurements: 1. 300 Hz to 6 kHz (or 12 kHz) spectral plots 2. 300 Hz to 3 kHz spectral plots (C) For underground narrowband measurements : 1. APD plots at 12 frequencies from 10 kHz to 32 mHz of magnetic field strength 2. R. M.S. and average values will be calculated based on time averaging for these plots (D) Sample spectral measurements of: 1. Roof-bolt voltages 2. Trolley wire-to-rail voltages 3. Phone line currents

Jan 1, 1973