Search Documents

By W. E. Coxe

In 1857 the Philadelphia and Reading Railroad Company, whose main line extended from Philadelphia to Pottsville, Pennsylvania, with branches into the coal regions of Schuylliill County, made a contract with the Fairmount Rolling Mill, at Philadelphia, for the rerolling of some four thousand tons of iron rails. The essential features of the agreement were that the old rails should be piled with puddled iron and rolled into flats for the rail pile, which latter was • to be of a section seven inches square, and after being heated, and reduced, by rolling, to a bloom of a section about fire inches by six inches, was to be reheated, before being finished into the rail of the T pattern, four inches high, weighing sixty-four pounds per yard. Great care was exercised in the execution of this contract, and the rails being distributed over all parts of the road, gave general satisfaction by their excellent wear. Five years afterward, the principal proprietor and manager of the Fairmount Rolling Mill was elected President of the Reading Railroad, and very many of the rails made under his supervision were still in use in the tracks of the company, of which he had just assumed the management. His first efforts were, therefore, directed to the procuring of more rails of the same quality wherewith to replace those worn out. Here he encountered some trouble, makers refusing to bid because of the details in the specification, the required reheating being the objectionable feature, for which it was generally intimated they would not be sufficiently remunerated for the increased labor, extra coal consumed, and the changes necessary from the established methods of working. Most of the new rails were, therefore, bought, and the old rails rerolled without regard to any particulars as to the manner of piling, heating, etc., each manufacturer furnishing what he deemed the best article possible for the money. As a consequence, rails of all imaginable grades were placed in the tracks, some giving out in six

By W. E. C. Coxe

IN 1857 the Philadelphia and Reading Railroad Company, whose main line extended from Philadelphia to Pottsville, Pennsylvania, with branches into the coal regions of Schuylkill County, made a contract with the Fairmount Rolling Mill, at Philadelphia, for the rerolling of some four thousand tons of iron rails. The essential features of the agreement were that the old rails should be piled with puddled iron and rolled into flats for the rail pile, which latter was to be of a section seven inches square, and after being heated, and reduced, by rolling, to a bloom of a section about five inches by six inches, was to be reheated, before being finished into the rail of the T pattern, four inches high, weighing sixty-four pounds per yard. Great care was exercised in the execution of this contract, and the rails being distributed over all parts of the road, gave general satis¬faction by their excellent wear. Five years afterward, the principal proprietor and manager of the Fairmount Rolling Mill was elected President of the Reading Railroad, and very many of the rails made under his supervision were still in use in the tracks of the company, of which he had just assumed the management. His first efforts were, therefore, directed to the procuring of more rails of the same quality wherewith to replace those worn out. Here he encountered some trouble, makers refusing to bid because of the details in the specification, the required reheating being the objectionable feature, for which it was generally intimated they would not be sufficiently remunerated for the increased labor, extra coal consumed, and the changes necessary from the established methods of working. Most of the new rails were, therefore, bought, and the old rails rerolled without regard to any particulars as to the manner of piling, heating, etc., each manufacturer furnishing what he deemed the best article possible for the money. As a consequence, rails of all imaginable grades were placed in the tracks, some giving out in six

Jan 1, 1877

By R. C. Palmer

The testing of flotation oils has occupied a large part of the time of the testing departments of various companies using the flotation process in the beneficiation of their ores. The great differences in ores and in oils has made such work necessary, as it has not been possible to select the oil best suited for the purpose without trial of many kinds. In fact, individual shipments of flotation oils from the same manufacturer will often differ so radically that the mill men have been forced to test every lot of flotation oil before its use in the mills. Further, although almost every imaginable product of the distillation of wood, from alcohol to pitch, has been tested in a more or less perfunctory manner by various people, few companies have allowed the results of their tests to be made public. This work was undertaken for the purpose of obtaining reliable data regarding the value as flotation agents of a number of products that are obtained from the distillation of wood by different methods, and incidentally to determine whether some of the products not used at present could be used. Large quantities of such materials are being masted or burned in the wood-distillation plants of the United States, and if some use other than fuel could be found for these materials, such a use would represent a distinct saving to the country as a whole, would increase the profit of wood-distilling plants now operating and perhaps make it possible for others to operate which at present cannot do so except at a loss. At the same time it was thought that if such products can be used as flotation agents, then their use would serve to increase the number of oils and other products available for flotation purposes. It was also hoped that it might be possible to discover a substitute for some of the most effective but comparatively high-priced oils which are now used for flotation

Jan 1, 1917

By Robert Wamsley, W. E. Jones

One of the earliest problems in the life of any community is the provision of an adequate supply of water sufficiently free from all types of contamination to be suitable for domestic purposes. Generally speaking, the location of most communities is determined to a great extent by the availability of an adequate supply of satisfactory water. For a mining camp, that consideration cannot be foremost. Here, the ore takes first place, and the men who mine it must do the best they can under the existing conditions. If there is no local source of water, it must be brought from some distant source or must be found by sinking shafts or drilling wells. Fortunate indeed is the mining company that discovers a commercially valuable ore deposit beside a never failing creek full of pure water, with sufficient water rights available. because the acquisition of water in any other manner nearly always involves not only a considerable period of time but the expenditure of considerable money. The experience of Climax Molybdenum Co. demonstrates the measures that sometimes are necessary in order to provide a suitable supply of water. The Climax mine and mill are on the Continental Divide! about 13 miles northeast of Leadville. The elevation of the domestic part of the camp varies from a minimum of 11,320 ft. to a maximum of approximately 11,550 ft. above sea level, and, as is common at such altitudes, the near-by streams that might be suitable for a water supply are small and intermittent, usually flowing only during the summer months. The only streams of any size in the immediate vicinity of Climax are the Ten Mile and Arkansas Rivers The headwaters of Ten Mile River are on the Company's property, and its water has been used for the domestic supply. The headwaters of the Arkansas River are about 2 miles distant and have not been used as a source of supply by the company. During the past 11 years of the production of molybdenum at Climax, the number of families living there has increased from about 45 to 283, and the population has increased from about 200 to 1200 persons. Consequently, the capacity of the water-treatment facilities, and the amount of water available, had to be increased to meet the requirements of the camp. As early as 1932 it was recognized that the water in Ten Mile River would not continue to be adequate for domestic purposes and after considerable discussion it was decided to drive a drift through the major fault in an effort to find additional water. This drift was completed in 1935 and tapped sufficient water to make the supply adequate. This water was treated in a tank underground, where lime was added, and was then piped into the domestic supply lines. At about the time this line was completed, the presence of fluorine in harmful concentrations was discovered in the water. This problem was submitted to the International Filter Co. and in November 1937 a plant of its design was put in operation for treating the water to remove the fluorine. This plant proved entirely successful,

Jan 1, 1946

By ARCHIBALD DOUGLAS

AT various times during the past quarter century proposals have been made that the basic Federal mining law of 1872 be repealed or amended, and that in its place a new and simpler law be enacted to provide for the entry upon, working, and the taking up of claims on the unallotted Federal mining lands in our western states and in Alaska. Serious discussion and study have been given such proposals but little has resulted there from, except perhaps a lively interchange of opinion and the conclusion that though the Apex law of 1872 is in many ways highly unsatisfactory and frequently a fomenter of strife and trouble, it still bids fair to remain with us. Under this act a greater part of the non-ferrous mining industry of the United States has developed. With all its short-comings it is the legal bridge that has carried over the innumerable caravans of adventurers and prospectors who explored our mining frontiers. For without any amendments of substance this act has for fifty-eight years been the guide in the location of our western Federal mineral claims and has stood unchanged during the most important period of our mining history. While Federal and state acts and amendments have been ground out by thousands and tens -of thousands the mining act of 1872, with a :strange tenacity, has remained as constant as the Rock of Gibraltar, and under it states, mining districts, and local customs have developed different codes for its application but its fundamentals have been unaltered. "Use doth breed a habit in a man"; until now the application of the law of 1872 has become a second mining nature.

Jan 1, 1930

By C. H. Benedict

Largest and most important of the milling plants under construction during the year is the Morenci plant of the Phelps Dodge Corp., in Arizona, where plans are being rushed for production in 1942. Grate mills will be used for fine-grinding, and in the pilot plant, classifiers of the spiral type have the preference for the closed- circuit work. The flotation units will be chiefly of the pneumatic type, with some mechanical units as auxiliaries. The Fagergren, Pan American, and Agitair machines were left in the competition as the year closed. If the absence of European markets for finished products has dislocated the mining industry, fortunately the lack of raw materials required in the beneficiation of ores has not been serious. except possibly as to the inability to import flint grinding pebbles. Some of the less important gold mines still use pebbles for grinding as is also the practice in the comminution of nonmetallics used in various industries. T the Calumet & Hecla in the Lake A Superior copper district pebbles have been used exclusively in open- circuit grinding in the Hardinge mills treating the

Jan 1, 1941

By John F. Abel

Personal gain seems to be the most powerful incentive to economic progress. One of my first exposures to this phenomenon was the comparison between company stopes and leaser's stopes in a vein gold mine. The company stopes were 4 to 6 ft wide, whereas the leaser's stopes were so narrow that in some places one could not turn around. The company leased only that ground it felt was marginal to mine with day's- pay miners, but by skillful, careful and energetic mining, the leasers managed in most cases to make money for themselves and the company. The Hurting Truth This capitalist system, which puts a premium on successful risk taking, is under attack. Not that it hasn't been under attack all along. What hurts and angers us at this time is that the attack comes from the children of the system-its youth. Such blasphemy should, of course, be eradicated, root and branch. Or should it? Are we hurt in part because some of the things they say are true?

Jan 1, 1970

By Charles Willis

THE problem of the curtailment of forces in large numbers does not often come to employment departments and is, therefore, a problem that many departments are not prepared to handle intelligently. Those companies that are able to measure the individual efficiency of each man would probably lay off men according to their individual ability, irrespective of dependents, citizenship, or other considerations. During the war when labor was scarce, the business of the employment manager in industry was hiring men and carefully placing them where they were best fitted to work. The careful selection of employees had developed to a considerable extent before the war, and was becoming a recognized science. In the last few months, however, the cancellation of copper contracts, the accumulation of large stocks, the necessary curtailment of production because the copper could not be sold, and lack of any immediate prospects of the copper market opening, have led to a universal reduction of forces; and the problem that industry now confronts is that of discharging rather than employing. The problem has been aggravated by the cancelation of contracts in many war industries with the consequent turning loose of hundreds of thousands of men, a great amount of unemployment, and the return of the soldiers and sailors. The problem has now become one of reduction of working force with the least hardship and the least injustice, and yet caring for the returning soldiers, sailors, and marines who have been in the service of the government for nearly 2 years, and who have offered the supreme sacrifice. The Copper Queen Branch of the Phelps Dodge Corpn., operating at Bisbee, Ariz., found it necessary, along with all of the-other copper companies of the country, to reduce its force materially. In making this reduction it was, after due consideration, decided to classify employees with respect to dependents, length of service, and citizenship. The question of individual efficiency or workmanship was not considered. Copper

Jan 9, 1919

Book Review MAN-TO-MAN: THE STORY OF INDUSTRIAL DEMOCRACY. By John Leitch, Phila¬delphia, Pa. The B. C. Forbes Publishing Co., New York, 1919, 2.19 pp., 7 1/2 X 5 in. $2.00. "Man to Man" is a short, well-written, well-printed, easy to read and very interesting hook. It is an account of a method introduced into more than twenty industrial plants to give the workers a share in managing their own troubles. It is not a panacea for labor troubles and strikes, but neither have existed where the new method has been tried. The scheme is, in a word, to organize the working force like the government, having a cabinet composed of the executives, a senate composed of foremen, and a house composed of men elected by fellow workers from all departments. This governing machinery takes up all complaints of workers, investigates, reports, and settles. The increased profits due to economy and increased production from this cooperation are divided 50-50 between the company and the men. Experience has shown that, since inattention, tardiness, irregularity, and inefficiency tend to reduce their profits, all men very quickly, after once convinced of the sincerity of the management in their scheme of cooperation, eliminate them because it is for their personal profit. Astonishing results have been attained, including higher wages, greater output, lower unit costs, great reduction in labor turnover, elimination of waste, an increased loyalty and a waiting list of employees even in periods of labor shortage. Profit sharing as such and stock ownership as a benefit to industrial relations are discussed briefly and illuminatingly, although they are not believed by the author to he the best way to bring about the human relation between those who work,for and those who work with money. The author is not against unions but does not believe the union is the best medium for improving industrial relationship. The look is nowhere dogmatic but is always forceful and convincing and, being well written, is very entertaining. It is doubtful if "Industrial Democracy" is the right expression for the solution of the problem but certainly anything that will place on the shoulders of labor some of the responsibility of industry and will increase production is tine much-to-be-desired desideratum. It is a. contribution to the solution of our biggest problem and should be read by everyone who employs men and who has been worried by the labor turnover. P. E. B.

Jan 7, 1919

By R. C. Palmer

THE testing of flotation oils has occupied a large part of the time of the testing departments of various companies using the flotation process in the beneficiation of their ores. The great differences in ores and iii oils has made such work necessary as it has not been possible to select the oil best suited for the purpose without trial of many kinds. In fact, individual shipments of flotation oils from the same manufacturer will often differ so radically that the mill men have been forced to test every lot of flotation oil before its use in the mills. Further, although almost every imaginable product of the distillation of wood, from alcohol to pitch, has been tested in a more or less perfunctory manner by various people, few companies have allowed the results of their tests to be made public. This work was undertaken for the purpose of obtaining reliable data regarding the value as flotation agents of a number of products that are obtained from the distillation of wood by different methods, and incidentally to determine whether some of the products not used at present could be used. Large quantities of such materials are being wasted or burned in the wood-distillation plants of the United States, and if some use other than fuel could be found for these materials, such a use would represent a distinct saving to the country as a whole, would increase the profit of wood-distilling plants now operating and perhaps make it possible for others to operate which at present cannot do so except at a loss. At the same time it was thought that if such products can be used as flotation agents, then their use would serve to increase the number of oils and other products available for flotation purposes. It was also hoped that it might be possible to discover a substitute for some of the most effective but comparatively high-priced oils which are now used for flotation

Jan 8, 1916

By George E. Roberts

THE gains of society from the state of primitive conditions in the past to the standard of living which prevails in the advanced countries today have been accomplished mainly by the increasing productive capacity of the population under the leadership and services of the engineer. Without improvements in the arts and industries the growth of population tends to place succeeding generations always at a disadvantage. In this country we have been exploiting with reckless prodigality a wealth of soil and minerals and timber that has been in preparation for thousands of years. We know that the prices of all national products have been advancing, and were on a rising scale even before the phenomenal increases resulting from the war. Over against this depletion of natural wealth we have the influence of improvements made in the methods of production and distribution-and the accumulation of wealth in the form of productive equipment. The net result of these opposing influences determines whether society moves forward or backward.

Jan 1, 1926

By P. Barnes

The sums given in the accompanying table are those actually paid for material and labor up to about August, 1875; but, as some parts of the machinery were not wholly completed at the starting of the works in September, 1875, the statement cannot be taken as an absolutely correct note of the total cost. A complete description, with engravings of the building and machinery, was given in Engineering, April 26th, 1878, in a paper by Messrs. A. L. Holley and Lenox Smith, to which convenient reference may be made. A detailed list of the construction accounts has been given in a paper, by the present writer, in vol. vi, Transactions of the Institute. A summary is given in the table of the items in each class which enter into the total cost, and also a note of the proportion which each of these items forms of the whole. A concise view may thus he obtained of the facts embodied in the statement as a whole, even though it cannot lay claim to completeness in showing the entire or final cost. An urgent suggestion has reached the writer from a distant country that such statements of cost to be really most serviceable should give the details in days of labor, in weight of iron, and in number of brick, and to this an assent is most cordially yielded. It is true, however, that the mere labor of copying arid compiling these details to such a degree of minuteness, would be very great, and, in any event, the probable difference between the plans of an existing establishment and one projected, would be so wide as to render even so complete a statement of cost of little more real service than the approximate notes given herewith.

Jan 1, 1879

By M. O. Holowaty, C. M. Squarcy

Blast furnaces are the tools of men, and it is men who have made them great. Here is presented the story of the Ironmakers-the men who first poured hot metal into what would someday be the sinews of a nation. W HEN the Jacobean merchant adventurers bade farewell to the first ship of colonists sailing for the new land, they instructed them to direct all their skill and energy to grow silk worms in Virginia. The adventurers felt sure that they could flood the market with highly priced and much desired goods like silk, sugar, tea, and indigo. They were also convinced that they would fill the needs of the mother country for iron. Early iron production in the colonies The merchants certainly had a wonderful imagination, for silk and indigo were just as exotic in Virginia as they were in England. The settlers found it more profitable to raise tobacco on the vast stretches of the free, fertile land. Thus the plans of settlers clashed with those of The Virginia Co.; and only point of agreement was the desire to produce iron. But, even there the motives of the settlers and those of The Virginia Co. of London were worlds apart. The settlers wanted to produce the tools badly needed in the colony, while the Company desired to cash in on the rising demand for iron which the home industry could not satisfy. Both the settlers and the Company lost no time trying to find iron ore. Locations of the early mines are not known. If, however, the reports of the Irishman, Francis Maguel, can be trusted, as early as 1609 a ship sailed for England with a load of 17 tons of crude iron which the East India Co. purchased at £ 4 per ton. The iron was of excellent quality and considered the best iron made of non-English ore that was ever purchased.

Jan 1, 1961

By Walter H. Ortel, George B. Wallace

INTRODUCTION A greater understanding is required about the factors which control tunneling operations if we are to meet the expected demand for tunnels. Much of the needed information can best be achieved by the proper use of instrumentation and advanced engineering concepts. Tunnel measurements and their analysis may prove to be the key which will give the insight necessary to understand the relationship of rock, tunnel supports, and linings. There are three main areas which can be improved through the use of tunnel instrumentation. First, and of prime importance, is safety for men and the project. When unstable conditions occur, sets become distorted. Even without measurements, it is sometimes possible to tell when trouble is approaching. In effect, the set acts as a load cell. Distortions in the set indicate reinforcements may be required to maintain stability. Additional sets or rock bolts, if they are placed soon enough, may provide this stability. However, when large rock displacements occur in short periods of time, it could be too late. Figure 1 is an example of the difficulties encountered in stopping moving rock. To stop the movement and possible failure, large props were placed above the spring line and the massive concrete gravity buttress was constructed along the legs. Rock bolts from the buttress deep into the rock were also used in an attempt to stabilize the rock mass. However, this work is for a highway tunnel and eventually these props and buttresses must be removed.

Jan 1, 1971

By Henry F. Herley

The New Orient mine, owned and operated by the Chicago, Wilmington & Franklin Coal Co., has caused a great deal of comment and interest because of its unusual features and huge daily production. It is in Franklin County, Illinois, adjacent to the town of West Frankfort. The seam being mined is the Illinois No. 6 which in this locality is 9 to 12 ft. thick and lies approximately 500 ft. below the surface. Without fear of contradiction, it can be said that this is one of the largest coal mines in the world from a daily production standpoint. During 1928, New Orient produced 2,400,000 tons, which amounts to over 10,000 tons each day the mine operated that year. The mine is built for a capacity of 12,000 tons but has actually hoisted over 15,000 tons in one 8-hr, shift. This enormous production can perhaps be better visualized if it is realized that each day's operation depletes over two acres of coal. The general features of this mine have already been fully covered in a paper by George B. Harrington,' President of the Chicago, Wilmington & Franklin Coal Co. In a paper of the nature of Mr. Harrington's, it was unnecessary to stress any particular phase of mining conditions, consequently the ventilation problems were touched upon but lightly. In this paper an attempt has been made to describe some of the problems which have been encountered in providing adequate ventilation for the mine. Ventilating Conditions The acreage allotted to New Orient mine has a length, north and south, of approximately 6 miles, and a width, east and west, of 2 to 4 miles. A number of important considerations caused the hoist shaft, air shaft and surface plant to be located near the southeast corner of the property, instead of near the center, as is usual. During the initial phase of the mine development, the mine was ventilated through these shafts, although there was a full realization that at some future date other shafts would be required.

Jan 1, 1930

By F. M. Lewis, J. F. Myers

The crushing of ore, as defined by Taggart, is "usually a stage process, utilizing . . . machines especially suitable for the reduction of particular sizes. . . . down to a final stage, employed for the reduction of the finest sizes. ... In contradistinction, comminution to 20-mesh or finer is called grinding. There is a twilight zone in which the product is 6, 10, or 14-mesh limiting size which is either crushing or grinding. ..." Since the data in this paper pertain to a rod-mill operation, comminuting a particular ore size of ¾ in. to a final stage, coarser than 20-mesh, the rod mill is designated as a "fine crusher machine" in this paper. The published literature discloses a wealth of data regarding a rod mill as a fine-grinding machine but relatively little as a fine-crushing operation. Typical of the latter operation is: (I) a description by F. J. Tuck2 in which a fine-crushing rod mill replaced crushing rolls and (2) a description by the present authors3 in which a fine-crushing rod mill was installed instead of a collventional fine-crushing machine. The experience of the authors is that a definite distinction must he made between the rod mill functioning as a fine crusher and as a fine-grinding machine. As a fine crushing machine it prepares relatively large amounts of ore for a subsequent fine grinding operation; as a grinding machine, it grinds relatively small amounts of ore to some predetermined finished product. Pulp Movement and Action in Mill In considering the work performed by a fine-crushing rod mill, it seems important to understand just what takes place within the mill. We were inspired to study this matter by a paper by E. W. Davis,4 which indicated that definite water classification of ore particles took place in a ball mill. However, in thinking of the rod-mill action from this point of view, we were confronted with the fact that our rod-mill discharge product showed no evidence of action by water classification. The Tennessee Copper Co. ore is relatively high in sulphides, and the gangue rock and the sulphides are of about the same hardness. In the presence of any action by classification, the coarser sizes are definitely very lean in sulphide minerals.

Jan 1, 1947

By J. F. Myers, F. M. Lewis

The crushing of ore, as defined by Taggart, is "usually a stage process, utilizing . . . machines especially suitable for the reduction of particular sizes. . . . down to a final stage, employed for the reduction of the finest sizes. ... In contradistinction, comminution to 20-mesh or finer is called grinding. There is a twilight zone in which the product is 6, 10, or 14-mesh limiting size which is either crushing or grinding. ..." Since the data in this paper pertain to a rod-mill operation, comminuting a particular ore size of ¾ in. to a final stage, coarser than 20-mesh, the rod mill is designated as a "fine crusher machine" in this paper. The published literature discloses a wealth of data regarding a rod mill as a fine-grinding machine but relatively little as a fine-crushing operation. Typical of the latter operation is: (I) a description by F. J. Tuck2 in which a fine-crushing rod mill replaced crushing rolls and (2) a description by the present authors3 in which a fine-crushing rod mill was installed instead of a collventional fine-crushing machine. The experience of the authors is that a definite distinction must he made between the rod mill functioning as a fine crusher and as a fine-grinding machine. As a fine crushing machine it prepares relatively large amounts of ore for a subsequent fine grinding operation; as a grinding machine, it grinds relatively small amounts of ore to some predetermined finished product. Pulp Movement and Action in Mill In considering the work performed by a fine-crushing rod mill, it seems important to understand just what takes place within the mill. We were inspired to study this matter by a paper by E. W. Davis,4 which indicated that definite water classification of ore particles took place in a ball mill. However, in thinking of the rod-mill action from this point of view, we were confronted with the fact that our rod-mill discharge product showed no evidence of action by water classification. The Tennessee Copper Co. ore is relatively high in sulphides, and the gangue rock and the sulphides are of about the same hardness. In the presence of any action by classification, the coarser sizes are definitely very lean in sulphide minerals.

Jan 1, 1947

By William Paxton Hewitt

Mineral deposits of western Utah and eastern and central Nevada have produced in excess of $8,500,000,000 since 1871. Through 1965, Bingham Canyon had produced over $4,600,000,000 and seven other camps over $100,000,000 each, principally from base metals. In addition, they yield iron and uranium ores; contain the world's largest beryllium reserves; and have produced the United States' most important gold discovery in 25 years. The area is famous for its silver production and its bonanza-type precious metal deposits, but such production has become unimportant. The area's greatest producers of metallic wealth are base-metal deposits in limestones and porphyry-type copper ores. In contrast to silver's decline, gold production has been rising-the result of by-product operations at Bingham Canyon. The area also contains gold deposits in which the gold is so finely disseminated it is not recoverable by panning. The area's gold ores frequently are associated with realgar, cinnabar, and carbon. The ore deposits generally are attributed to Tertiary intrusives,* but, at Mountain City, they may be related to Paleozoic volcanism. Mountain City has yielded rich chalcocite from quartz-pyrite-chalcopyrite bodies in siliceous sediments. Regional stratigraphy and structure are difficult to interpret, 69 per cent of the area being obscured by alluvium or volcanics. In general, central Nevada consists of chert, shale, silty sandstones, lavas, and pyroclastics; eastern Nevada and western Utah of many alternations of limestone, shale, and sandstone. Central Nevada has been structurally active since late Devonian. Although granitic stocks may have intruded eastern Nevada and western Utah prior to the Cretaceous, these areas remained quite stable until affected by the Laramide Revolution. Precambrian exposures, occupying 3 per cent of the area, have not been important hosts. However, the question is raised as to whether Precambrian carbonates, properly situated with respect to invading mineralizers, might yet prove to be important. This paper describes 16 precious metal camps, 6 limestone replacement districts, 2 silver-base metal vein deposits, and 9 miscellaneous types and discusses briefly the 11 * Some ores, as at Ely, are associated with intrusives of. Cretaceous age. major camps that are described in detail in this Volume.

Jan 1, 1968

By RUSSELL C. FLEMING

THE important advances that have been made of recent years in mining and milling methods and in mechanical equipment at mines need no re- telling, but there has been a remarkable growth in one type of equipment which has gone nearly unnoticed. That is the increasing use of storage-battery locomotives underground. Since the war the number of these locomotives and their field of use have increased tremendously; their growing acceptance represents an al- most complete reversal of opinion from an earlier period when they were generally looked upon as in- adequate for the strain of mine service. At the time when storage-battery powered units were first making their bid for recognition, the use of power in haulage had already passed through several phases; hand tramming, rope haulage, compressed air locomotives, even gasoline locomotives, had all been used, ending finally in the general adoption of the electric trolley locomotive for practically all power-haulage requirements. It was, and is, conceded that the trolley loco- motive met more adequately the varied and severe conditions of mine service than any previous type of haul- age unit. Subsequent developments have had to endure comparison and surpass in performance that type of haulage before changes would be considered.

Jan 1, 1930

By W. S. Morris

THE East Texas oil field is the largest in the United States and perhaps the largest 'in the world ; likewise, it is one of the most interesting. The East Texas oil field is a water-drive field. Small amounts of salt water were produced from wells on the western side of the field from the bt-ginning of the development. By the end of 1933 (the field having been discovered in September 1930) water production had reached 9000 barrels per day. By the end of 1936, approximately 2000 wells were producing about 45,000 barrels of water per day, and the problem of salt water disposal attracted the serious attention of the operators. Salt water production in the field has steadily increased and today approximately 450,000 barrels of water per day is produced while the oil production averages about 375,000 barrels. The disposal of this salt water has therefore become one of the major operating problems. Various methods of salt water disposal have been tried in the East Texas field. Evaporation in open pits proved

Jan 1, 1944