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By Clemens Catesby Jones

The substance of this paper, now amended and altered in form for its present use, was the basis of a private report prepared under professional engagement.* A private report is necessarily objective, and deprived of the scope and technicality of a scieintific treatise—which accounts for the prevalence of drawings and succinct mathematical statements rather than full descriptive details in a paper reproduced from data, of which all the original working-notes have been destroyed. In a practical sense the Hudson river valley clay-deposits owe their present existence to the protection afforded by the rock-formations on which they are supported, and, instead of being uniform in depth or continuity, are subject to the irregularities of the rugged masses which preceded and are now concealed by them. The only available information concerning these deposits contained in previous public reports or maps furnished at best a mere photograph of the surface, and as now apparent this was misleading or unreliable. It was the object of this investigation to determine in a practical manner the location, form and extent of all the clay-deposits at present existing in the lower Hudson river valley, and to ascertain with a

Jan 1, 1900

By E. S. Leaver

THE amount of gold that occurs in a ton of milling ore from most of the large-scale copper mines is so small that unusual care and special attention are necessary to recover it. In some cases the gold is not considered important enough to warrant daily assays of the various products. Considering the large tonnage of copper ores that are now concentrated by flotation, as computed in a recent review, the gross gold content is surprisingly large, probably amounting to over 10 million dollars per year in the United States. The indications are that in many of the copper-milling operations with gold content under $1 per ton, only 50 per cent. of the gold is recovered in the flotation concentrates. Lime is generally used as a depressant for pyrite in the flotation circuit. The authors have shown that high lime or a solution high in calcium ions is also a depressant for gold. Their experiments on several well-known ores show that by careful regulation of the alkalinity of the mill solutions, a higher flotation recovery of the gold can be obtained, together with equally good copper recovery in a good grade of copper concentrates. In cyanidation for the recovery of gold, the best accepted practice demands that the mill solutions be tested and regulated by simple chemical reactions at definite periods during treatment or with each change in the treatment. It is similarly important for the recovery of gold that the solution in the flotation circuit be analyzed for calcium ions at regular periods and at each step in the flotation practice. The lime should be added when and where needed and not in excessive amounts at the head of the mill.

Jan 1, 1931

SLAG composition, slag constitution, reactions in slag, and reactions between slag and metal-in other words, the physical chemistry of slags-are matters of great importance to the open-hearth operator, whether or not he makes use of any detailed knowledge of them. Although this is a relatively young branch of the science of steel- making, much progress has been made; however, much remains to be learned, and many of the statements that can be made at present are probably--or even certainly-subject to future change. Nevertheless, the physical chemistry of slags is sufficiently developed to provide a reasonably secure basis for real understanding of steelmaking reactions. FUNDAMENTALS OF SLAG CONTROL By way of introduction, some time is spent in this chapter on effecting an easy transition from some of the more "practical" manifestations of slag to discussions couched in the more formal language of physical chemistry. This necessitates a certain amount of repetition, but it is felt that the purpose of the chapter is best served in this way. Reactions in the metal phase have products that find their way into the slag and are important components thereof; they are discussed in detail in the preceding chapter. Some substances distribute themselves Between slag and metal in definite fashion, and others are found only in the slag. Their reactions are a large reason for this chapter. Limitations of Slag Control. The open-hearth process is essentially oxidizing and cannot be otherwise operated. (Oxygen gradients in the furnace, the mechanism of oxygen inflow, and similar subjects are discussed in Chapter XIX.) As shown in the calculations of material and heat balances for the charge (see Chapter XV), from 25 to 50 lb. of oxygen will flow from air or combustion gases into the charge or molten bath during the heat for each ton of liquid steel

Jan 1, 1944

By O. W. Ellis

IN VIEW of the extensive use of the brasses and bronzes in engineering practice it is indeed surprising that so little scientific work has been done on the oxides in these alloys. Recognition of the ill effects of these compounds is universally accorded, both in foundry procedure and in such specifications as cover the melting of these useful mixtures. In the latter, limits, for example, are placed on the proportions of scrap metal in the charge, and clauses governing the use of fluxes are included, the addition of fluxes to the charge being made with the object of avoiding oxidation during the process of melting and of subducing and separating non-metallic matter from the melt.1 In the manufacture of brass it occasionally, though rarely, occurs that the virgin metals, copper and zinc, alone are used. In the event of virgin metals being employed, that of the higher melting point is always melted first. If it is melted under suitable conditions, little or no oxidation will occur. Whether oxidation has occurred or not, however, can best be determined by microscopic examination of a sample taken from the melt.

Jan 1, 1930

COMPLYING with your frequently expressed wish and, your persistent request, I have decided to prepare a brief little book on metallic ores, based on ,the books of the ancient philosophers and on the experience of practicing miners, that will instruct you how to judge from promising indications which rock forma¬tions, which veins, stringers, or mineral matter are likely to bring. forth metallic ores so that it would be promising and gainful to work them. It explains according to the best of my ability, in separate chapters, as much as you need to :know for your, chosen profession or business, about such things as the favorable characteristics of the terrain, the strike, and dip* and outcrop of veins in general, and also about each metal in particular. Young Knappius: † Then it will be explained to me logically in. this little book and I shall be given a reasonable understanding which mines can be worked gainfully so that my investment will not be wasted but will show a profit. Daniel: Everybody should, of course, use his intelligence and should educate himself well and diligently to become able to understand, [2]‡ as far as that is. possible, from what matter, by what means, and where metals are generated by. Nature; and as a mere side issue he should not spurn the profit that ensues there from. But if his aim is solely and predominantly profit and gain rather

Jan 1, 1949

By A. E. Lehman

A RECENT demand for some form of panoramic display of an important railway line, showing its branches, connections, and terri tory controlled by it, revealed to the writer the advantages of' a topographical model or relief map fix this purpose. Hitherto, maps of this nature have been used chiefly for scientific and geographical purposes, and confined to a comparatively narrow field of service. They deserve to become more popular and to have their advantages better understood. Much has been written and accomplished in this direction by Prof. Lesley, Messrs. Harden, Moulten, de Mendonca Cortez, and others; but I believe their pub lished descriptions of the methods employed in the construction of these models are confined to those used by themselves. It is the writer's aim to present in condensed form these various methods, and some suggestions of practical value as to the most economical course of procedure, as well as to mention some of the uses that may be made of the results obtained Methods of Construction.—Many different materials have been prepared and used in the preparation of relief maps, such as metal, clay, plaster, gypsum, wax, putty, Card-board, papier-mache, wood, and compositions of varions kinds, with results more or less success ful : wood, however, in the writer's experience, has been found to be by far the most satisfactory, combining the advantages of stability, accuracy and ease of handling. The following is a brief description of several of the methods used in constructing topographical models : When clay, wax, putty, compositions or materials of a plastic nature are used, the operator carries his work up from its base by means of measurements or by the eye, manipulating and shaping the material as best he can, ac cording to such features of his subject as he wishes to delineate. This process requires remarkable skill, and given this, will probably fall short even then of an approximation to accuracy; lacking essential elements of detail nil over the work and exactness, particularly in position and elevation of the most important points in the territory mapped. When either of the above mentioned materials or compositions are used, metal or wooden pins are sometimes driven into the base or level datum plane of wood, the top of these pins giving the eleva-

Jan 1, 1886

By Harold Cook

THE purpose of this paper is to state briefly the inspection requirements of the Bureau of Ordnance, the specifications governing the inspection, and the physical and chemical properties of the steel used in the construction of ordnance for our Navy. It would be of interest to evoke discussion on points in these specifications which do not tend to insure the production of the very best material for the purpose intended. In other words, what requirements of our specifications are useless and also in what manner are our specifications deficient? It might be well at the, start to answer the first criticism of this paper which will probably be made, and that is that the title does not agree with the subject matter. Considering metallographic work as covering only the macroscopic and microscopic examination of metals, this paper will have gone beyond the subject; but it is believed that a broader definition of metallography is that it is the study of the relation of the internal structure of metals and alloys to their composition and to their physical and- other properties. The internal structure of steel is dependent on its physical and its chemical properties. These physical properties are dependent on the chemical composition and the mechanical and thermal treatment of the steel. So it seems that this subtitle would not be entirely necessary and that the title "Metallography of Steel for Ordnance Purposes" would cover a study, not only of what we can learn of macroscopic and microscopic examination, but broadly of the whole subject of the specifications, the fulfillment of the requirements of which produce the structural conditions revealed by macroscopic and microscopic examination. .

Jan 2, 1916

By E. A. Reilly, G. R. Gardner, F. P. Lasseter

THE methods that may be applied to the treatment of slurries and water, as these are related to practical coal-preparation problems, are concerned essentially with the movements of solids suspended in water. It is assumed that there are no fundamental differences between the principles involved in the treatment of coal slurries and the phenomena encountered in general mineral-dressing practice, and the latter are presented in some detail. Basic principles ,are correlated with present practice for both the anthracite and the bituminous coal fields, and methods are discussed which are designed to utilize best all the material subjected to treatment and suggest a sound approach to the solution of problems relating to the return of clear water to process or to streams. In order to approach the practical phases of the subject with sufficient understanding of the basic principles, it is necessary to discuss two types of phenomena that are applicable. The first is flocculation and the second is sedimentation. Descriptive matter is given covering the various methods and types of equipment employed to conduct these operations, with emphasis on their application to water and coal-slurry treatment. DEFINITION OF TERMS Definitions of terms are consistent with modern developments, and on form, in general, with their usage in mineral-dressing practice. Because of variations in coal-preparation methods, it is impossible to define a rigid upper limit of particle size for a coal slurry or sludge which will apply generally. Limits vary somewhat with the particular treatment method employed at a given plant. For purposes of definition, this limit is chosen as the particle size for which preparation methods such as Chance cones and jigs are usually dispensed with, and other methods, such as the Hydrotator, tables, and froth flotation, are employed. Generally the limit will be 10 to 6 mesh. In assuming this variable upper limit of particle size in a coal slurry, it is recognized that the size ranges discussed will duplicate sizes dealt with

Jan 1, 1943

Mineral Industries education as an entity, again and again has sought recognition, always to be turned aside or ignored.1 The incident mentioned in Lost Chapter was only the first of a series of disappointments. The Land-Grant Act is camouflaged here and there in the name of progressive education. A new interpretation may be in the best interests of society in so far as the goose is not killed that lays the golden egg. The primary objective of the act is still "agriculture and mechanic arts" but mechanic arts is not alone mechanical arts or engineering. Mechanic arts was used in a broad sense as a symbol of creative effort in locating and winning the fundamentals of existence - plants, animals, and minerals - from Mother Earth, their primary processing and treatment into foodstuffs and raw materials of industry, their manufacture into useful articles of commerce, and, last, their distribution and utilization. Significantly the great agricultural industry is now at least half mechanic arts. The Association of Land-Grant Colleges and Universities has neglected the mineral kingdom shamefully. The Association embraces Divisions of Agriculture, Arts and Sciences, Engineering, Home Economics, and Veterinary Medicine but has no division relating to the mineral industries.

Jan 1, 1950

By George Stern

THE purpose of this investigation has been to study one method for making ordinary carbon steel by the powder metallurgy technique. This method con- [ ] sists of pressing and subsequently sintering an intimate mixture of iron powder and graphite in a suitable atmosphere to produce a steel. Two types of iron powder have been studied, electrolytic and reduced. The sintering of mixtures of loose carbonyl iron and carbon black for several hours at 1000° to 1100°C. (1830° to 2010°F.), followed by forging of the resultant ingots to bars, has been studied by Offermann.1 Trail' has reported on the properties of hydrogen-reduced and electrolytic iron powders, both containing 0.5 per cent carbon. Methods for making steel bodies by powder metallurgy have also been sug- [ ] gested by Goetzel,3 who recommends the addition of steel powder of well-defined carbon content to pure iron powder, and Volterra,4 who suggests compaction and subsequent sintering of a mixture of steel powder, iron oxide and iron powder. Additional methods for making steel bodies by powder metallurgy have been reported in the literature by Koehring,5 Allen,6 Balke,7 Wulff,8 Boegehold,9 and others. 10,11,12 It is felt that the method of pressing iron powder and graphite, as described herein, lends itself best to production because of the lubricating action of the

Jan 1, 1946

By I. N. Knapp

I Herewith present some notes on the use of Portland cement to cement in the casing, and for plugging, to exclude water from oil and gas wells, and the methods employed. I have used my best efforts to. make each step of the operation of cementing wells perfectly clear. The information is the result of actual experience and observation. The illustrations are from original drawings made especially for this paper. Portland Cement It is not necessary to discuss here the manufacture of cement. Any established brand of the slower setting Portland cements may be purchased with the confidence that it will harden, if properly used, and exclude water from and plug wells efficiently. Setting.—By the setting of cement is meant its initial change from a soft or plastic mortar to a friable solid. After the cement has become thoroughly set it is still very weak and can be readily pulverized in the fingers. Setting is thought to be effected by the crystallizing out of the silicate and the aluminate of lime, which are soluble in water in their anhydrous form. After dissolving in the water they pass to the hydrated state, in which they are insoluble, and hence are precipitated in a crystalline form. Ordinarily neat Portland cement mortar remains perfectly plastic for from 1 to 1 1/2 hr. after mixing with water at about 70" F. A higher temperature accelerates and a lower retards setting.. Hardening.—This is due to a continual crystallization of salts from solution, and to further chemical and physical changes which develop slowly, but which continue for long periods of time. Testing.—It is no more necessary for an operator to go into the scientific testing of cement to be used in a well than to so test the pipe used. He must depend for the quality of each on the tests and reliability of the manufacturer. Cement or pipe may be damaged in shipment so

Jan 1, 1915

By Thomas Fraser, H. F. Yancey

BefoRe a new coal-washing plant is installed, or an existing washery is remodelled and improved, considerable experimental work on the coal to be washed should be done. A thorough examination of a coal, to determine whether it can be washed successfully and the best and most economical process for securing a satisfactory grade of washed coal, calls for mine sampling, analytical work, and experimental coal-washing tests which may require several months' time and the expenditure of considerable money. Having collected the required data on the characteristics of the coal and the results secured with different types of machines under different sets of conditions, it is necessary to decide what method of treatment should be used. The interpretation of the experimental data is no small part of the problem. The first step in the investigative work is to determine from the characteristics of the coal and the manner of occurrence of the impurities whether it is possible to separate the dirt from the coal and produce a washed coal of the required quality. Then it is necessary to select the type of washer or the system of treatment that will produce the greatest amount of washed coal of this grade for the least cost. To secure this information, tests may be made at laboratories operated by consulting or contracting engineers, at the testing plants of machinery manufacturers, at commercial washeries, or in an experimental washery erected on the site of the proposed plant. Such tests will produce figures in which every factor, including analyses of raw coal and washed coal and yield of washed coal, may vary widely. To reduce these results to a common basis for comparison is very difficult. A number of plans

Jan 1, 1923

By Thomas Fraser, H. F. Yancey

BefoRe a new coal-washing plant is installed, or an existing washery is remodelled and improved, considerable experimental work on the coal to be washed should be done. A thorough examination of a coal, to determine whether it can be washed successfully and the best and most economical process for securing a satisfactory grade of washed coal, calls for mine sampling, analytical work, and experimental coal-washing tests which may require several months' time and the expenditure of considerable money. Having collected the required data on the characteristics of the coal and the results secured with different types of machines under different sets of conditions, it is necessary to decide what method of treatment should be used. The interpretation of the experimental data is no small part of the problem. The first step in the investigative work is to determine from the characteristics of the coal and the manner of occurrence of the impurities whether it is possible to separate the dirt from the coal and produce a washed coal of the required quality. Then it is necessary to select the type of washer or the system of treatment that will produce the greatest amount of washed coal of this grade for the least cost. To secure this information, tests may be made at laboratories operated by consulting or contracting engineers, at the testing plants of machinery manufacturers, at commercial washeries, or in an experimental washery erected on the site of the proposed plant. Such tests will produce figures in which every factor, including analyses of raw coal and washed coal and yield of washed coal, may vary widely. To reduce these results to a common basis for comparison is very difficult. A number of plans

Jan 1, 1923

By Henry Howland

INTRODUCTION DURING the last decade no topic has created more interest or received more thought among blast-furnace men than colic. One reason for this is, undoubtedly, the remarkable increase in the use of byproduct coke. Formerly our coke was made at a distance from the furnaces and by a distinct organization. There was little cooperation or development possible under these conditions. Today the situation is greatly changed. Much of our coke is made by the organization operating the furnaces and the coke oven is operated with the primary object of obtaining the best results in the blast furnace. The effect of changing the method of coke manufacture, even in some minor detail, is often felt almost immediately at the blast furnace. There naturally results one of the most valuable assets of the byproduct coke oven, -i.e., the possibility of increased blast-furnace efficiency clue to close observance and correct operation of the ovens. The results are evident, but it often is difficult correctly to account for them. In attacking the solution of a problem of as much importance as why one coke is better than another, there are facts which should be kept clearly in mind The author hopes, in this paper, to bring out some points relative to the use of carbon in the blast furnace which will be of value in solving this question.

Jan 3, 1916

By Bradley Stoughton

[Secretary's Note.—TO avoid repetition of foot-notes, references to authorities are made in this paper by means of figures, referring to a numbered list in the appendix.—J. S. 1 Introduction. This paper gives the results: first,, of a research into the somewhat extensive literature of titanium; and second, of a series of original tests upon the effect of titanium on iron castr ings. New investigations have also been made upon the effect of titanium on steel, but I hope to treat this subject in an independent paper at some later date, and, therefore, will not discuss the experiments in detail here. The combined results of this study, which extended over a period of more than two years, can be briefly summarized as follows : 1. Steel or cast-iron, in which the titanium is properly proportioned, and which has been properly treated, is improved in strength, toughness, and durability against wear, such 'as, for example, the wear of railroad-rails, of steel and chilled-iron rolls, car-wheels, etc. 2. These improvemerits seem to be caused, not so much by the direct effect of titanium on the metal, as by its cleansing influence in removing harmful impurities, such as oxygen and oxides, nitrogen, occluded slags, and perhaps also sulphur. It appears also to reduce segregation, which would contribute to the same end. 3. In order that its effects may be fully realized, the treatment of steel or iron with titanium must be correctly performed. There are a few simple, but essential, details to be observed; if they are neglected, the best results cannot be expected. To illustrate by an example: A series of tests on cast-iron

Jan 1, 1913

By Frank R. Van Horn

In the summer of 1908, R. B. Cochran, Superintendent of the Compania Metalurgica Mexicana at Sierra Mojada, Mexico, presented to the Department of Geology and Mineralogy at Case School of Applied Science an interesting series of silver-, copper-, and lead-ores from the Veta Rica mine. These ores contained several interesting minerals which were associated in a somewhat peculiar manner, so that I was impelled to make a closer study of their occurrence. The investigation has brought out several new facts concerning the geology of the district and the geological occurrence of the ores, and therefore has seemed worthy of record. Two papers have been published previously about the region, one by Chisml in 1887, and the other by Malcolmson² in 1902. These articles, however, treat of the district more from the stand-point of the metallurgist and mining engineer, and not much attention is devoted to its mineralogy and economic geology. 11. Geographical Location of the District. The Sierra Mojada is situated in the extreme western part of the State of Coahuila, near the Chihuahua boundary. It is reached best via the Mexican Central railroad from El Paso, Tex., to Escalon, Chihuahua, a distance of 494 miles. From this point, a branch line, the Mexican Northern railroad, runs 78 miles in a NE. direction to the mines, which are its northern terminus. The railroad was built about 1890, practically on account of the Sierra Mojada mining-district.

Jan 1, 1913

By Howard Eavenson

The data given in the paper were collected to furnish an idea of the amount required in various operations of bituminous mining to produce a ton of coal, the plants selected being well-managed ones. With these are included some figures compiled from U. S. Coal Commission's report showing the average amount of labor in various classes of mines. THE information contained in the following paper was collected at the request of the U. S. Coal Commission, and is, published with the permission of that body and of the various companies furnishing the data. For obvious reasons, the names of the companies are not given. No data were gotten from States south of Virginia or west of the Mississippi River. The data about the amount of labor, in man-hours, required in producing a ton of bituminous coal have been collected with the idea of showing what is being done at some well-managed plants, and not to show the average amount required by all mines, which undoubtedly is considerably higher than the average of the figures shown.* Almost all of the figures were supplied by the various companies in reply to a questionnaire; when they were obtained from other sources the company was asked to verify them. On account of the amount of work required, the data were only requested for one or two months for each plant, and the figures represent in each case a month when the car supply was good and the work was practically steady. In the case of most of the West Virginia and Kentucky mines, these conditions were best met in May and June, 1922. The mines for which the figures are given are arranged by states and as to whether the mine operates under union or non-union or open-shop conditions. The union mines listed are generally considered to be as well-managed as are the non-union ones. The production per month in a few cases includes the amount of slate which is loaded and hauled out of the mine, as of course this requires nearly as much labor per ton as does the coal. These cases are noted:

Jan 1, 1924

By Albert Sauveur

As director of the Division of Metallurgy of the Technical Section of the Air Service, American Expeditionary Forces, from August, 1917, to January, 1919, I devoted much time to the study of the steels best suited to the construction of aircraft. It became apparent at a very early stage of my investigation that the practice of builders varied greatly in regard to the number of different steels to be used, to the kinds of steels, and to their treatment. Some manufacturers employed as many as fifteen steels while the builder of one of the newest motors, favorably passed upon in the United States, assured me that two or, at the most, three kinds of steel were all he needed to produce satisfactory results. In the matter of treatment, the manufacturers were also greatly at variance. Some treated their steel with considerable refinement while others paid but scant attention to this feature. Some manufacturers case-hardened many parts, while others used the case-hardening process sparingly, if at all. Nickel-chromium steels were used at some works for case-hardening while at other plants this treatment was applied exclusively to carbon steels. Air-hardening nickel-chromium steel was used extensively by some and not at all by others. Considerable variance existed likewise in regard to the steels used for admission and exhaust valves. The conclusion was obvious, that no two manufacturers of airplane motors held like opinions as to the steels to be used or as to the treatment they should receive. Was it to be inferred from this that the many committees and associations that had been created, in part at least, for the standardization of aircraft steels had failed to make proper recommendations or that the manufacturers had ignored their recommendations ? Confining our inquiry to the committees and associations that had dealt with this question in England, France, and the United States, it was found that in Great Britain the British Engineering Standards Committee, now the British Engineering Standards Association, had devoted much time to the problem of satisfactory standards for aircraft steels. In April, 1918, this Association presented a set of specifications described as "British Standard Specifications for Aircraft Steels for Government Purchases in the United States of America." They included twenty-one different steels and, as the title indicates, were drawn for the

Jan 1, 1920

By Charles T. Holland

Miners have observed for many years that as pillars are removed in mining operations the pillar adjacent to those mined out frequently shows evidence of being compressed. Although this has been known for a long time, little or no information is available concerning how far from the mining area the pillars are affected in this manner, or how great is the magnitude of the compression, or concerning the manner or characteristic way in which the compression acts, as the mined-out area approaches the pillar under consideration. The writer made a study of pillar action in the Mona mine of the Arkwright Coal Co., partly to get some quantitative data on the deformation of coal-mine pillars. The study was not completed but it seems best to present the information that was obtained. Method of Measurement Fig. 1 shows the details of the apparatus used for measuring the deformation. This is permanently attached to the pillar. Fig. 2 shows the details of the gauge that records the deformation. This gauge is removable and was used to measure the deformation at all the stations. The recording dial is graduated in thousandths of an inch and records measurements up to one inch. Fig. 3 shows how the removable gauge is placed in the instrument. When installing the instrument in the side of the pillar, all loose coal near by was removed and a trench 4 to 6 in. deep, and approximately 1 ft. wide, was dug in the pillar. In this trench near the top and the floor, the holes holding the instrument were bored. These holes were then partly filled with thin cement and the rods were inserted. The remaining space in the holes was tamped full of cement. At this time, by carefully manipulating the permanent rods and clamps and adjustable pin, it was possible to adjust the instrument so that the removable gauge would stand true and measure any vertical deformation between the top and bottom rods. Fig. 4 is a photograph of one of the instruments installed, showing the removable gauge in place.

Jan 1, 1938

By Charles T. Holland

Miners have observed for many years that as pillars are removed in mining operations the pillar adjacent to those mined out frequently shows evidence of being compressed. Although this has been known for a long time, little or no information is available concerning how far from the mining area the pillars are affected in this manner, or how great is the magnitude of the compression, or concerning the manner or characteristic way in which the compression acts, as the mined-out area approaches the pillar under consideration. The writer made a study of pillar action in the Mona mine of the Arkwright Coal Co., partly to get some quantitative data on the deformation of coal-mine pillars. The study was not completed but it seems best to present the information that was obtained. Method of Measurement Fig. 1 shows the details of the apparatus used for measuring the deformation. This is permanently attached to the pillar. Fig. 2 shows the details of the gauge that records the deformation. This gauge is removable and was used to measure the deformation at all the stations. The recording dial is graduated in thousandths of an inch and records measurements up to one inch. Fig. 3 shows how the removable gauge is placed in the instrument. When installing the instrument in the side of the pillar, all loose coal near by was removed and a trench 4 to 6 in. deep, and approximately 1 ft. wide, was dug in the pillar. In this trench near the top and the floor, the holes holding the instrument were bored. These holes were then partly filled with thin cement and the rods were inserted. The remaining space in the holes was tamped full of cement. At this time, by carefully manipulating the permanent rods and clamps and adjustable pin, it was possible to adjust the instrument so that the removable gauge would stand true and measure any vertical deformation between the top and bottom rods. Fig. 4 is a photograph of one of the instruments installed, showing the removable gauge in place.

Jan 1, 1938