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By Fred H. Poettmann, J. K. Welchon, A. F. Bertuzzi

A series of gas-lift tests was made which verified conclusions reached from previous studies and which showed that gas-lift performance could be calculated if reasonably accurate data on the producing characteristics of the well are available.' The test installation is described. Its essential features consisted of a rate-of-flow controller to regulate the input gas and an auxiliary string of small diameter tubing to conduct the input gas to the point of injection in the eductor tubing. In general, it was shown that for continuous gas-lift operation, injection should be as deep as possible consistent with available gas pressure and rate of production desired. Calculated curves are presented which completely characterize the gas-lift performance of the well tested. INTRODUCTION A correlation based on field data from a large number of flowing and gas-lift wells, covering a wide range of oper- ating conditions, was developed which permitted the logical design and prediction of the performance of continuous gaslift installations.' The procedure made it possible to calculate the depth, pressure, rate at which to inject gas, horsepower requirements, and the effect of production rate and tubing size on these quantities. As a result of these calculations certain significant facts were brought to light or re-emphasized. The presence of efficient ranges of operation and an optimum injection depth for a given rate of production were shown to exist as well as the fact that the lower the tubing pressure the less the horsepower requirements to lift the reservoir fluids. The fact that the gas lift performance can be predicted by calculation does not mean that any given installation will perform over the entire range predicted. Many of the conventional continuous gas-lift installations will not permit operation over the entire range predicted by calculation (particularly in the efficient range of operation) because of the performance characteristics of the installation. Consequently, field tests were initiated for the purpose of investigating and arriving at a simple continuous gas-lift installation which would operate under all conditions predicted by calculation. The first series of tests involved the use of mechanically operated valves. These valves were slip-joint type valves which are opened and closed by lowering or raising the tubing at the surface by means of a hydraulic jack. These valves were chosen because it was hoped that they could be opened or closed at will and did not depend on the gas pressure in the annulus or the pressure of the fluid in the tubing for their operation. Unfortunately, the valves did not operate satisfactorily and it was imossible to open or close each valve at will. Some limited data were obtained, however, which verified the predicted benefits resulting from the use of lower tubing pressures. In the next series of tests the valves were removed and the gas was injected from the annulus through a 14/64-in. orifice equipped with a reverse check valve. A packer was set below the valve to seal off the space between the 2-in. tubing and 5-in. casing. The injection point was located at 3,810 ft. This arrangement provided satisfactory mechanical operation. However, it was impossible to obtain low rates of liquid production at low tubing pressures as predicted by calculation. A minimum gas injection rate existed below which steady flow was impossible. Liquid pro-

Jan 1, 1953

By J. C. Smock

THE magnetic iron ores of New Jersey are found in the northern part of the State, in the Highland Mountain range, which runs from the New York line on the northeast, to the Delaware River, near Easton, at the southwest. The same range continues across Orange County to the Hudson River, and towards the southwest it is known in Pennsylvania as the South Mountain. It is more properly an elevated table-land, quite deeply furrowed by several narrow, longitudinal valleys, and shorter cross-valleys or gaps. The ridges or lines of elevation, as well as the lower valleys, conform in their general direction very closely to the general trend of the whole belt or table-land, that is, from northeast to southwest. This also agrees with the prevailing strike of the rocks. This great uniformity in the altitudes of the hills and ridges, and the direction of the lines of depression corresponding to the strike of the strata, point to an original table-land, which, through the long action of denuding agents, has been quite deeply eroded, giving rise to the present surface configuration, so that some of the former and uniform features have been partially obliterated. The very few cross-valleys or depressions are much more irregular in their course, and serve as outlets through which the drainage is carried either into the Kittatinny Valley on the northwest, or to the broad, red shale and sandstone plane bounding the highlands on the southeast. The area of this highland

Jan 1, 1874

By J. C. Smock

The magnetic iron ores of New Jersey are found in the northern part of the State, in the Highland Mountain range, which runs from the New York line on the northeast, to the Delaware River, near Easton, at the southwest. The same range continues across Orange County to the Hudson River, and towards the southwest it is known in Pennsylvania as the South Mountain. It is more properly an elevated table-land, quite deeply furrowed by several narrow, longitudinal valleys, and shorter cross-valleys or gaps. The ridges or lines of elevation, as well as the lower valleys, conform in their general direction very closely to the general trend of the whole belt or table-land, that is, from northeast to southwest. This also agrees with the prevailing strike of the rocks. This great uniformity in the altitudes of the hills and ridges, and the direction of the lines of depression corresponding to the strike of the strata, point to an original table-land, which, through the long action of denuding agents, has been quite deeply eroded, giving rise to the present surface configuration, so that some of the former and uniform features have been partially obliterated. The very few cross-valleys or depressions are much more irregular in their course, and serve as outlets through which the drainage is carried either into the Kittatinny Valley on the northwest, or to the broad, red shale and sandstone plane bounding the highlands on the southeast. The area of this highland

By Stanley C. Suboleski, J. Richard Lucas

Simulator I, a program to simulate production in room and pillar mining systems containing up to six face operations, was developed at Virginia Polytechnic Institute under sponsorship of the Office of Coal Research. Since its inception, several hundred analyses have been run, with over thirty companies using the program. This paper describes the simulation technique used in this program, the output achieved from an analysis, and reviews the experience gained in working with Simulator I.

Jan 1, 1969

By C. E. Beecher

IN the course of the experimental and development work of Henry L. Doherty in an endeavor to obtain an increased yield of oil from oil-bearing sands, it was Mr. Doherty's claim and contention that oil in an undisturbed pool was different in character and behavior than, the same oil when raised to the surface of the earth, and that the gas dissolved in the oil caused a marked reduction in its viscosity and surface tension. Prior to 1924 no information to support this contention could be found in the literature or by a discussion of the subject with technical men in Government and private laboratories. So far as could be ascertained no experimental work had been carried on to indicate that Mr. Doherty's claim was either right or wrong. All parties consulted agreed that the viscosity of the oil would be affected by gas dissolved therein to the extent that natural gasoline was present in the gas, but so far as could be determined any additional effect of the natural gas was unknown. Accordingly, it was necessary to devise equipment and carry on experiments which would either prove or disprove Mr. Doherty's contention or claim. Such apparatus was built under Mr. Doherty's direction and experiments were carried on to determine definitely the viscosity and the surface tension of the crude oils which contain dissolved gases under different pressures. The results of the experimental work carried on have proved that the claim and contention of Mr. Doherty were correct in every particular, as will be seen from the discussion of the subject and the data contained in this paper.

Jan 12, 1926

Ernest R.. WOAKES, Cana, Colombia: The allusion in this paper, under the heading " Mining on the Isthmus," to the Espiritu Santo mine at Cana is neither according to fact nor worthy of the most interesting and able summary of the mining districts of Colombia contained in the remainder of the paper. The following remark is certainly open to contention: "The most widely-known mine of this department is the Espiritu Santo, at Cana, a quartz-mine opened up in 1680 and abandoned in 1727 on account of the attacks of the Cana Indians. This mine undoubtedly produced great quantities of gold, although many of the accounts given of its ancient richness are probably exaggerated. In 1884 it was rediscovered and reopened by the Darien Gold Mining Company, and under the able management of Mr. Thomas H. Leggett, now prominent in South African mining circles, produced for a time successful results ; but later the veins became pockety and the output unsatisfactory." The mine here referred to, though situated at Cana, was not the Espiritu Santo mine, and was closed down in 1892. Mr. Leggett, however, ran ten stamps on the ore from it for some two or three months in the year 1890, when he left Colombia. The Espiritu Santo mine was not reopened by the Darien Gold Mining Company until the year 1894. For the last three years the ore from the old Spanish workings of this mine has been yielding in the mill 1 ounce to the ton, and has served to keep the mine going whilst extensive development-works have been

Jan 1, 1899

By AIME AIME

ROBERT F. MEHL was born in Lancaster, Pa., March 30, 1898 and graduated from Franklin and Marshall College in 1919. He then went to Princeton and was granted his doctor's degree in physical chemistry in 1924. Two years as head of the department of chemistry at Juniata College, followed by a like period as National Research fellow at Harvard, working with T. W. Richards and Albert Sauveuir, satisfied Bob's immediate affections for college and university life and prepared him to turn temporarily to other fields.

Jan 1, 1938

By Robert B. Fulton

Staurolite, an iron aluminum silicate mineral, is used industrially as the source of aluminum in portland cement manufacture in areas where the aluminum constituent is not economically available from shale or argillaceous limestone. It is also used as a high value- in-use sand blasting agent and as a premium grade foundry sand. It is produced by E. I. du Pont de Nemours & CO. as a coproduct in titanium mineral production in Florida where it was first recovered on a commercial scale in June 1952 from the Pleistocene sand deposit known as Trail Ridge. In the Trail Ridge deposit it comprises about 36 of the heavy minerals, the principal other heavy mineral constituents being ilmenite, leucoxene, rutile, zircon, kyanite, sillimanite, and tourmaline. Staurolite and the other silicate nonconductive heavy minerals are separated from the conductive titanium minerals on high-tension separators. The silicates are then separated from one another magnetically, the staurolite being relatively magnetic. In the total processing, 200 tons of raw sand yield 7 tons of heavy mineral concentrate from which about one ton of staurolite is recovered. Staurolite production is approximately 100,000 net tpy. No other commercial production of staurolite is known. This process yields staurolite concentrates of the characteristics given in [Table 1]. These concentrates are sold as three products with the size distribution of subrounded particles shown in Table 2. All three grades are used in sand-blasting for cleaning metal, for paint removal, and for cleaning buildings. Staurolite compares favorably with lower unit cost abrasives, such as boiler slags and mineral aggregates, in applications where the abrasive is used only one time and is not recovered. Because it is hard, fine, clean, and dense it can reduce blasting time, with less material reportedly being required

Jan 1, 1975

By Andrew Roy

THE Mahoning Valley coal region lies on the extreme northern outcrop of the Ohio coal-field, and all the mines, with one exception, are opened on the lower coal of the series, No. 1 of the Ohio Geological Survey. The coal ranges from an inch to five, six, and sometimes seven feet thickness, the workable height being between two and a half and six feet. There are two varieties of coal, known in market as "Briar Hill coal " and " Mineral Ridge coal;" both varieties are drawn from the same seam. The Briar Hill coal is generally called block coal, and is the kind so largely used in a raw state in smelting iron. It pos¬sesses a laminated structure, easily splitting into horizontal sheets, but is very difficult to break in the opposite direction. The faces of the layers are often covered with a soft, dead, carbonaceous material, like charcoal, and the whole seam throughout is marked by alternate layers of dead and bright-looking coal. In the act of combustion the coal neither swells nor changes form, the masses retaining their shapes until they fall to ashes in the furnace. The Mineral Ridge variety is much softer, and is also shorter in the grain than the Briar Hill. kind, and it contains a good deal of

Jan 1, 1876

By Andrew Roy

The Mahoning Valley coal region lies on the extreme northern outcrop of the Ohio coal-field, and all the mines, with one exception, are opened on the lower coal of the series, No. 1 of the Ohio Geological Survey. The coal ranges from an inch to five, six, and sometimes seven feet thickness, the workable height being between two and a half and six feet. There are two varieties of coal, known in market as "Briar Hill coal " and " Mineral Ridge coal;" both varieties are drawn from the same seam. The Briar Hill coal is generally called block coal, and is the kind so largely used in a raw state in smelting iron. It possesses a laminated structure, easily splitting into horizontal sheets, but is very difficult to break in the opposite direction. The faces of the layers are often covered with a soft, dead, carbonaceous material, like charcoal, and the whole seam throughout is marked by alternate layers of dead and bright-looking coal. In the act of combustion the coal neither swells nor changes form, the masses retaining their shapes until they fall to ashes in the furnace. The Mineral Ridge variety is much softer, and is also shorter in the grain than the Briar Hill kind, and it contains a good deal of

By E. C. W. Perryman

The recovery of X-ray line broadening, hardness, and electrical resistivity from cold worked AI-Mg alloys has been investigated. The results, together with those from density measurements, suggest that magnesium atoms freeze in the excess vacancies formed by cold working, and that this affects the climb of dislocations during the recovery process. PREVIOUS work1, " has shown that while 1 pct Mg increases the activation energy for recrystalliza-tion, it decreases the activation energy for the recovery of mechanical properties and decreases the subgrain size both after cold working and annealing. A similar result has been reported by Varley2 for an A1-2 pct Mg alloy. With plastic deformation at high temperatures, McLean and Farmer' and Rachinger have found that magnesium appears to retard the motion of dislocations and, furthermore, they find little or no effect of magnesium on the size of subgrains formed during high temperature deformation. In view of the apparent contradictions as to the effect of magnesium on subgrain size, the recovery process in Al-Mg alloys has been investigated more thoroughly by studying the annealing out of X-ray line broadening, hardness, and electrical resistivity from alloys cold worked at room temperature. Material Used—The chemical analyses of the alloys are given in Table I. Fabrication—The material used was cold rolled 20 pct at room temperature, the grain size prior to the last cold rolling operation being similar to that used in previous work; i.e., 230. The experimental procedure for annealing, determination of X-rav half-veak breadth. hardness measurement, electEica1 resistivity, and density and metallographic examination was exactly the same as previously described." Variation of X-Ray Half-Peak Breadth with Annealing Time—Isothermal annealing curves at 100°, 200°, and 250°C were obtained for material cold worked 20 pct. The half-peak breadth of the (333) Ka, line directly after cold working is shown as a function of magnesium content in Fig. 1. Only with the 2.87 pct Mg alloy was overlapping of the a, and n.. reflections observed to any appreciable extent. To separate these, Rachinger's method' was used. Typical isothermal annealing curves are shown in Figs. 2 and 3 for 100" and 200°C, respectively. These curves are similar to those obtained previously for super-purity aluminum except that the

Jan 1, 1957

By E. S. Machlin, S. Weing

GRAIN boundary stress relaxation has been the subject of several investigations in recent years, but as yet the phenomenon is not well understood. One of the major difficulties has been the lack of a sufficient amount of data with which to evaluate any proposed mechanism. Little information is available on the effect of small amounts of substitutional solutes on grain boundary stress relaxation. It is with this important phase of the problem that this investigation is concerned. The influence of substitutional solutes on grain boundary stress relaxation has been recently investigated in copper by Pearson: and in aluminum by Dorn et al.' Pearson studied the effect of zinc, gallium, germanium, and arsenic on the relaxation peak of OFHC copper.* The pure OFHC copper decreased the peak intensity and a second peak appeared at a higher temperature. This latter peak was termed the alloy grain boundary peak. At the lowest binary concentration studied, approximately 1 atomic pct, the primary peak was almost completely obliterated. Pearson found that the activation energy calculated from the alloy grain boundary peak for all solutes, irrespective of the concentration, was 44,000 cal per mol. Pearson concluded that the increase in activation energy from 33 to 44 kcal per mol is not continuous but abruptly changes from the lower to the higher value. As no attempt was made to investigate the intermediate range of concentration and hence calculate the possible variation of the activation energy for the initial grain boundary peak, this conclusion is hardly valid. In contrast to these results, Dorn et al. studied the effect of zinc, silver, copper, germanium, and magnesium on the grain boundary stress relaxation of aluminum. No change in the energy of activation was observed for binary alloys of the flrst four solutes, but a linear increase was found for increasing concentration of magnesium. Saturation was not found up to the maximum of 1.6 atomic pct. The energies of activation were obtained by plotting the horizontal displacement of the dynamic modulus curve vs temperature for two vibrational frequencies. As the modulus is proportional to the square of the frequency, this requires the measurement of the torsional frequency over a range of temperature. However, the technique does not lead to an unambiguous interpretation of the grain boundary

Jan 1, 1958

By C. L. Horn

All the tunneling machines discussed in this chapter are Calweld machines. I have divided the machines designed for soft-to-medium formations into three groups, correlated with typical formations and estimated compressive strengths: 1) Running sand and silt requiring blade cutters. 2) Chalk and clay, requiring drag-type cutters, for compressive strengths ranging from 0 to 2000 psi. 3) Sandstones, hard clays, and limestones, requiring disk cutters, for compressive strengths ranging from 2000 to 20,000 psi. All of the soft-to-medium-formation machines are powered by electric hydraulic or diesel hydraulic pumps. The pumps in turn drive hydraulic motors for the torque reaction. The soft-to-medium-formation machines are enclosed in a 360º shield with a cutting shoe, a center portion of the shield housing the mechanical equipment, and a tail shield. Tunnel supports are usually required, and the supports are normally erected in the tail shield. Our first machine was built in 1963, and all but five of the machines illustrated in the figures with this chapter were built in 1966 and 1967. Some of the machines manufactured will be discussed in the following sections; specific features as development has progressed will be pointed out. HARD-ROCK MACHINE The Calweld hard-rock machine has been designed along basic and accepted principles for a hard-rock mechanical borer. The features of this machine are as follows: 1) Direct electric motor drive through a planetary gear reduction ring and pinion gear, and then to the cutting head through a hollow drive shaft.

Jan 1, 1970

By R. S. Lewis

IN a recent study1 of the evolution of engineering education 1870 was taken as the initial point, as it is said to mark the transition from the poineer era in American engineering education to an era of rapid growth and consistent development. Prior to the founding of Rensselaer Polytechnic Institute in 1824, West Point Military Academy was the principal source of formal engineering training. In 1849 Rensselaer revised its program on the model of the leading French technical schools. Lawrence Scientific School was estab-lished at Harvard and Sheffield Scientific School at Yale in 1847. The University of Michigan pioneered in en-gineering instruction in the West, offering its first course in 1853 and awarding its first degree in 1860. Other important steps in -the progress of engineering education were the founding of Columbia School of' Mines in 1864, the opening of Massachusetts Institute of Technology in 1865, and the founding of Cornell Uni-versity and the Thayer School of Civil Engineering at Dartmouth in 1867. From its organization in 1852 until 1871 the Ameri-can Society of Civil Engineers was virtually the only national society of engineers. In 1871 the American Institute of-Mining and Metallurgical Engineers was founded, to be followed later by the Mechanical En-gineers in 1880 and the Electrical Engineers in 1884. This expansion and diversification of the engineering profession was paralleled in the colleges, and by 1885 the plan of different curricula in the major branches of engineering was soundly established.

Jan 7, 1927

By G. Thodos, R. B. Grieves

A method has been developed For predicting the critical temperatures and critical pressures of binary mixtures of carbon dioxide, hydrogen sulfide, nitrogen, hydrogen, carbon monoxide and oxygen with the normal paraffin hydrocarbons. For carbon-dioxide and hydrogen-sulfide systems, relations are presented that take into account the peculiar behavior of mixtures with closely boiling components, such as carbon dioxide-ethane and hydrogen sulfide-propane mixtures which exhibit minimum critical temperature points. For hydrogen, nitrogen and carbon-monoxide systems, the extreme critical behavior caused by wide differences in pure component properties is established In addition, those fixed gas-paraffin systems which resemble paraffin-paraffin systems are also accounted for. For a mixture of known composition, the pure component critical temperatures, critical pressures and normal boiling points are all that are required to determine its critical point. Graphical relations are presented relating Tc and PC , of the mixture to the pure component properties. From the treatment of 12 carbon-dioxide and hydrogen-sulfide systems reported in the literature (74 mixtures), the expected error lor the critical temperature is approximately 1.5 per cent, and for the critical pressure, approximately 2 per cent. From the treatment of six hydrogen, nitrogen and carbon-monoxide systems reported in the literature (30 mixtures), the expected error for both the critical temperature and critical pressure is approximately 2.5 per cent. The relationships, which have been developed with only normal paraffins as the hydrocarbon components, may be extended to those isoparaffins and olefins which fall within the allowable volatility ranges. INTRODUCTION Many of the fixed gases — carbon dioxide, hydrogen sulfide, nitrogen, hydrogen, carbon monoxide and oxygen — occur in natural mixtures with hydrocarbons. Carbon dioxide and hydrogen sulfide are frequent components of the fluids produced from underground petroleum reservoirs. Nitrogen, carbon dioxide and hydrogen sulfide are present in varying quantities in most natural gases and gas-condensate well effluents. Hydrogen mixtures are of considerable interest in many phases of refining processes of petroleum. The determination of the critical temperatures and critical pressures of such mixtures is of value in vapor-liquid equilibrium studies, for the prediction of the characteristics of underground reservoirs, and for reduced-state correlations of PVT, transport and thermodynamic properties. The accurate estimation of the critical point for binary mixtures is an important initial step toward a complete analysis for the establishment of the critical temperatures and pressures of multi-component mixtures. Methods for predicting the critical temperatures and critical pressures of binary hydrocarbon systems have already been presented in the literature.8 It is possible to apply these existing methods to fixed gas-paraffin mixtures, but due to their unusual critical behavior, values calculated deviate considerably from experimental values. For systems containing trace quantities of the fixed gases, these methods are acceptable; however, for systems containing more than 5 mol per cent of the fixed gases, these utterly fail to produce reasonable critical values. Consequently, in this study a method has been developed for handling such binary mixtures over the entire composition range. CARBON-DIOXIDE AND HYDROGEN-SULFIDE SYSTEMS The critical behavior and the vapor pressure behavior of mixtures of carbon dioxide and hydrogen sulfide with paraffinic hydrocarbons may be quite similar or quite dissimilar to that of paraffin-paraffin mixtures, depending on the volatilities of the components involved. The critical temperature and normal boiling point of carbon dioxide are very close to the corresponding values for ethane, while its critical pressure is considerably higher than that of ethane. The normal boiling point of

By Kenneth Robertson

THERE is probably less known of this subject than of any other connected with the metallurgy of iron. In all the books that treat of this matter, there ore given analyses of slags, their chemical formulae, the loss of iron, etc. ; but few, if any, give the character of the iron mode at the time; none give analyses and physical characteristics of the ores and limestones used, and they present merely isolated examples from various furnaces, and consequently one is more frequently puzzled than enlightened after reading them. During two years I have had occasion to analyze the slags and many of the pig-irons from two furnaces, and for this article I hove made analyses of all the different grades of pig mode by them. A

Jan 1, 1873

The Midvale Plant of the United States Smelting, Refining and Mining Company, situated twelve miles south of Salt Lake City, consists of mills for concentrating lead-zinc ores and a custom lead smelter. The milling department includes a 475-ton gravity mill for ores from the United States Mines at Bingham, a 100-ton Huff electrostatic zinc plant and a 60-ton pilot flotation mill for differential separation of lead and zinc. The gravity mill and electro- static plant are being replaced by a 600-ton differential flotation plant, now under construction, for differential separation of lead, zinc and iron. This new mill will have capacity for treating custom ores in addition to ores from the company's mines at Bingham.

Jan 1, 1925

By Eckley B. Coxe

AT the first meeting of the Institute, a paper was read by Mr. Rothwell, calling attention to the importance of at once considering the great waste of anthracite coal under the present system of mining and preparing that fuel for market, and a committee was appointed to examine and report upon the method now in use. About the time the committee were selected, a general resumption of work, after the long strike, took place in the coal regions, and the members of the committee have not in consequence had as much leisure to devote to the study of the question as its importance de¬mands. In the present preliminary report we shall merely sketch out the plan which we propose to pursue in our investigations, so that when our fellow-members are called upon to assist us in our work by fur¬nishing statistics, etc., they may understand more clearly for what object our inquiries will be made. As one of the most practicable methods of obtaining the informa¬tion requisite for an intelligent consideration of our subject, we pro¬pose to send, from time to time, to members and others interested in the mining of anthracite coal, printed sets of questions relating to points under consideration. We would here impress upon our fellow¬-members the importance of filling up these papers as far as they can from their own knowledge. We would, of course, wish each ques¬tion to be answered as fully as possible, but we do not expect every one to answer them all. One question well answered would be of more use to us than the whole paper filled up with answers, many of

Jan 1, 1873

By Eckley B. Coxe

At the first meeting of the Institute, a paper was read by Mr. Rothwell, calling attention to the importance of at once considering the great waste of anthracite coal under the present system of mining and preparing that fuel for market, and a committee was appointed to examine and report upon the method now in use. About the time the committee were selected, a general resumption of work, after the long strike, took place in the coal regions, and the members of the committee have not in consequence had as much leisure to devote to the study of the question as its importance demands. In the present preliminary report we shall merely sketch out the . plan which we propose to pursue in our investigations, so that when our fellow-members are called upon to assist us in our work by furnishing statistics, etc., they may understand more clearly for what object our inquiries will be made. As one of the most practicable methods of obtaining the information requisite for an intelligent consideration of our subject, we propose to send, from time to time, to members and others interested in the mining of anthracite coal, printed sets of questions relating to points under consideration. We would here impress upon our fellow members the importance of filling up these papers as far as they can from their own knowledge. We would, of course, wish each question to be answered as fully as possible, but we do not expect every one to answer them all. One question well answered would be of more use to us than the whole paper filled up with answers, many of

“IT is decreed by Divine Providence that those who know what they ought to do and then take care to do it properly, for the most part meet ' with good fortune in all. they, undertake; on the other hand, misfortune overtakes the indolent and those who are careless in their work." These are the words of Georgius Agricola. to. those who are engaged in mining, taken from De Re Metallica, Book II, second paragraph. Safety in mining is just that simple, when considered on the basis of the individual. The words imply a .knowledge of what is to be done and how to do it. Armed with this knowledge it is only necessary to proceed with diligence and care to achieve the desired end without personal or financial mishap. Obviously the complication arises in the large company operating numerous mines and the consequent ramifications of company structure embodying management, supervision, engineering, and labor. Agricola stresses later on the importance of supervision and direction by the owners of the mine. We know that this principle is recognized today by the frequency with which the statement is repeated "a safety program must stem from management." People charged with responsibility for safety and management also stress the importance of securing the cooperation of the employees in formulating and carrying . out safe working practices. Safety committees consisting of employees, supervisors, and. representatives of management are recognized as the most practical method of achieving safety consciousness in all levels of mining company organization.

Jan 1, 1952