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By Thomas B. Douglas

INSTRUMENTATION in the process industries can no longer be regarded as a convenience, but rather an absolute necessity. Although many chemical processes must already be conducted with instruments, every properly designed application of automatic process control will improve operation: 1) the product will be more uniform and of higher quality; 2) the manual labor saved will reduce cost; 3) uniformity of flow and uniform control of process will increase production; and 4) surges will be eliminated, making it possible to operate equipment near ultimate capacity at all times. Industrial instruments fall into two general classifications—those that measure and those that measure and control. The cement industry has been using instruments for a number of years, particularly in the burning process, primarily for indicatlng and recording. Automatic process control makes additional use of these instruments, and others, to control variables. Assisted by the instrument manufacturers, engineers at Ideal Cement Co. achieved considerable progress in determining how well the usual recording instruments could be made to control various phases of cement-making. The results of these experiments were used to make the new plant at Houston as wholly automatic as possible. The original Houston plant, built in 1937 by Gulf Portland Cement Co., consisted of only one 8 x 220-ft kiln and the necessary grinding mills and accessory equipment and had a capacity of 900 bbl per day (300,000 bbl annually). Ideal Cement Co. purchased this plant in 1940 and almost immediately started plans to increase its production. In 1941 a 9 x 220-ft kiln was installed and grinding and storage capacity were increased. The growing demand for cement in the Houston area necessitated a third kiln (9 ft 6 in. x 250 ft) in 1947. This brought the plant up to its present capacity of about 1.3 million bbl per year. Calcium silicates in cement are produced in a burning operation at high temperatures from raw mix of argillaceous and calcareous materials that have been crushed, mixed, and ground to a fine powder. The composition of this mixture must be kept consistent within narrow limits. Raw mixing and grinding may be done either wet or dry, but in both instances the materials must be correctly proportioned, finely ground, and thoroughly intermixed before entering the kiln. As the raw mix passes through a long horizontal rotary

Jan 1, 1959

By L. Frank, Nason

THE complete statistics of zinc-ore production in the United States for 1916 are not yet available. The following figures are, therefore, only approximate. The total production of concentrates for this year, including New Jersey and Tennessee, amounts to 1,280,000 tons. Of this tonnage, five mines produced approximately 536,000 tons, or about 42 per cent. The remaining concentrates came mainly from the "Valley States," Missouri, Wisconsin, Kansas, Oklahoma, and Arkansas. The 1,280,000 tons of concentrates represent about 25,000,000 tons of crude or run-of-mine ore. Of the five mines producing the 42 per cent., the dimensions of three are approximately 25 by 1,500 by 2,000 ft. (7.6 by 457 by 610, m.) or more. Tour of the five mines are undoubtedly veins in the common acceptance of the term. They are located in great vein systems. The mines of "Valley States" have not, so far, been classed as veins; simply as "secondary deposits." The origin of these secondary deposits has been a warmly debated subject. Many geologists contend that they are the results of leaching from overlying and from adjacent rocks carrying but traces of zinc, these traces leached out and deposited in favorable loci. If this theory is correct, deposition is strictly limited to shallow depths. No volume of ore comparable to that of "true fissure veins" is to be expected. Just what this means to the future of zinc mining in these States is here indicated. The total zinc areas of these States amounts to about 9,124- sq. miles (23,631 sq. km.).- Assuming that 10 per cent. of this total will be more or less productive, there are 912 sq. miles (2,362 sq, km.) of "mineral? ground. The average depth of the operated mines is something like 100 ft. or less. In Bulletin 606, U. S. Geological Survey (1915), p. 202, Siebenthal makes the following statement: "The writer is informed by William Waugh, one of the drillers of the Stone City well, that cuttings from other wells which he drilled in the vicinity of Pittsburgh, Kan., have shown galena and sphalerite taken from a depth of 591 ft. (180.14 m.) and that the showing of ore at some places would be considered good enough to justify the sinking of a shaft had it been found in the Joplin district and at shallower depths." Leaving out of the question the prohibitive cost of such a shaft, there is

Jan 5, 1917

By John V. Beall

On weekends things get pretty interesting out our way because the fleet is usually in. Our No. 2 son is now based at New London, which Isn't far from here, and he brings his friends home. No. 1 son is a re- cent Navy veteran, and he lives at home. It is just as well that the Pentagon can't hear what is said. This is all aside from the point except that last Friday evening, Dave Meinhard, a redheaded nukie (nuclear sub crewman) from Indiana, commented on our late arrival home In obvious need of a pick-me-up. "Just like my dad; but he has it rougher than you. We live in La Porte, Ind., and every day he drives 35 minutes to work at Bridgeman, Mich., and loses an hour on the time zone. It's really exhausting. You should see him." We feel very sympathetic. He should receive extra pay. However, extra pay benefits are hard to come by although the reverse comes relatively easy. For example Grass Valley, Calif., was such a nice place to live 25 years ago that they compensated for it by making an appropriate deduction for the s

Jan 1, 1971

By James Gayley

(Wilkes-Barre Meeting, June, 1911.) THE paper presented to the Institute in 1910, by H. 0. Hofman, on Recent Progress in Blast Roasting,1 has called the attention of the iron industry to the adaptability of these processes to the reclamation of by-products such as flue-dust and blue billy, and the better preparation of concentrates and fine ores for use in blast-furnaces. The waste of valuable iron-ore through the production of flue-dust has increased at an enormous rate, and much of it has in reality been wasted as far as future recovery is concerned. Only in recent years has a possible future value been recognized, and the material stored. The increased use of Mesabi ores, which carry considerable fine ore, is principally responsible for the great increase in the production of flue-dust. The amount of fine material that is carried over depends on the fineness of the material and the velocity of the gases, and also to a very great extent on the regularity or irregularity of the working of the furnace. Attempts to recover a part of this loss have been made by recharging a portion of the production into the furnace, but as this material has been once carried out from the furnace, it is naturally in good shape to be carried out again. A recent practice at some works, is to soak the flue-dust thoroughly with water to give it more cohesiveness, but by many this is considered of doubtful advantage in the furnace, and the gases are in consequence heavily laden with moisture. There are vast deposits of magnetic iron-ores in the United States and Canada that are too low in iron for use at the present time, but which can be economically concentrated into very rich material ; in many cases the fineness of crushing necessary to secure proper concentration has prevented their

Aug 1, 1911

I do not think too much emphasis can be placed upon creation of favorable climate for development of foreign mineral resources to feed the hungry maw of our industrialized nation. We have become dependent, not only upon the ten raw products indicated in Mr. Bancroft's article, but upon 71 mineral substances listed by DMPA as in short supply. Forty-four of these are metals, 9 are chemical minerals and 18 are nonmetallic minerals. Of this list only 8 are produced in any large quantity in the United States, and all are vital in peace-time industry. Even more, they are absolutely essential for defense. This represents our present needs. But if our consumption and requirements are projected over the next 25 years as is done by the President's Materials Policy Commission-The Paley Report-our future outlook becomes appalling. The divergence of consumption over production, even allowing for substitution and conservation, will widen in the future. This means our dependence upon foreign raw materials, mainly minerals, will grow. What are the chief foreign sources of minerals for our future needs? They are chiefly Latin America and the dominions and colonies of the Western European nations. The British Commonwealth countries contain in abundance those minerals which the U. S. lacks. Of 32 of the most critical minerals the Commonwealth is deficient in 7 and lacks only 1; whereas the U. S. is deficient in 18. Strikingly, our deficient minerals are abundant in the Commonwealth and several of their deficiencies are in excess in the U. S. Resources of the two nations complement each other. If Europe should be overrun by an unfriendly power that could control the destinies and resources of the European dominions and colonies, our industrial life would be placed in severe jeopardy. Therefore, I heartily endorse Mr. Bancroft's statements regarding the Point IV program, provided the program is wisely administered and implemented. It is from the underdeveloped countries, as pointed out by Mr. Bancroft, that most of our future mineral supplies will have to come. Many of the underdeveloped source countries are African colonies and dominions of Western European nations. Our present aid to Europe, therefore, is not, as many infer, a purely one-sided affair; it safeguards our future industrial development and security. Development aid directly to the underdeveloped countries through a well administered Point IV program, can do much, I believe, to safeguard our prosperity. I regard it as a wise investment for future U. S. mineral needs. Dr. Alan M. Bateman Department of Geological Sciences Yale University Mr. Howland Bancroft's article, The Broadening Road to Foreign Investment, appeared on page 666 of the July MINING ENGINEERING.

Jan 1, 1952

By J. S. Ross

OIL-FIELD waters enter into many underground problems with which the petroleum engineer has to deal. Whether the problem is one of infiltration or natural encroachment, it is always desirable to determine the source of the water before commencing repair or remedial work. The usual mechanical tests for determining the source of extraneous water in wells are slow and expensive. An excellent means for the identification of oil-field waters may be afforded by their chemical characteristics when the chemical character of waters from the various sands has been established, by careful sampling and analysis cautiously interpreted. In the Salt Creek field, Wyoming, a fairly high degree of efficiency has been attained in the controlof field operations by utilizing the information afforded by the analysis. All of the operating companies appreciate this means of identifying waters, with the result that water-sampling has become general practice. Most of the chemical work dealing with Salt Creek waters has been done since the laboratories of the Midwest Refining Co. and the U. S. Geological Survey, were established in the field; the former in 1922, the latter in 1924. A spirit of cooperation has existed between the company and the government personnel by which many of the data for this paper were made available.

Jan 1, 1928

By Dever Ashmead

ENGINEERS, operators, miners, and others di-rectly interested in mining will readily agree that more of well-directed illumination in mines will result in a reduction of accidents and general im-provement in the working conditions, comfort, and effi-ciency of those employed underground. Progress has been made in the amount of illumination from individual lamps carried by miners. The candle, which a great many of us can remember as the general method of lighting, was replaced by the oil lamp or torch, later by a specially prepared oil known as "Sunshine," and eventually by the carbide cap lamp. The metal mines still present a field for progress from the standpoint of general illumination, particular-ly those mines having high stopes. Attention is being more and more focussed upon the advantages of im-proved lighting in mines, in order that the underground employee may benefit as the factory workers have al-ready done. The management is vitally interested in the morale of its employees, the reduction of costly accidents and increased production, all of which, judging by results in other industries, will be sub-stantially benefitted through the means of improved general illumination. From data available to the writer, 40 to 50 per cent of the accidents in the metal mines occur at the face; they may be due to roof falls, movement of loose ore, loading of cans, handling of tools, etc. Very probably a large proportion of these accidents may be attributed to lack of light. If sufficient illumination had been present the employee could have seen what was happen-ing and taken the proper precautions. The introduc-tion of better illumination means better visibility, de-crease in accidents, and increase in efficiency.

Jan 6, 1928

Still, the subject of iron ore is associated in peoples' minds mostly with the Lake Superior region and this is as it should be. The Minnesota Section meeting exposed the forces that over a period of two decades, 1950 to 1970, are revolutionizing the industry. The Lake Superior region has been at the center of these changes and has been deeply affected by them. The rise of foreign sources of iron ore that did not require beneficiation and taxation considerations were for a number of years a giant setback for the Lake Superior region and Minnesota in particular. However, the companies in this region have led the drive to improve the quality of ores which are culminating in the tailored pellet. This is a product in which iron content, silica, without significant impurities, is manufactured for optimum blast furnace performance. The oxide pellet does not seem to be the end as partially or prereduced pellets are closer at hand.

Jan 3, 1966

By Dodge, C. E.

ONE of the first mining areas to be developed in Arizona was that in the district centering about Clifton and Morenci. Traces of metals were first noticed by Henry Clifton on an expedition in 1864. Definite copper outcroppings were also reported in the following year by General J. H. Carleton when he led his troops into the district on an Indian raid. Actual mining operations were started in the early seventies. and the first smelter was finished in 1873. Two adequately financed companies acquired most of the property, and both commenced production about 1882. These were the Arizona Copper Co.. owned by a group of Scotch investors, and the Detroit Copper Mining Co., afterwards purchased by the firm of Phelps, Dodge & Co. Later the Shannon Copper Co. acquired and operated a number of claims in the northern part of the district. These three companies all operated underground, mines independently for many years.

Jan 1, 1942

Discussion of the paper of Leonard Waldo, presented at the New York meeting, February, 1911, and printed in Bulletin No. 76, April, 1913, pp. 555 to 559. HERBERT HAAS, San Francisco, Cal. (communication to the Secretary*):-Referring to Leonard Waldo's paper on Temperature Conversion Tables, I believe the following formulas can be easily remembered, and by reference to the thermomter scales of Fahrenheit (F.), Celsius (C.), and Réaumur (R.), their derivation and relation are at once understood n° F. = 4/9 (n°-32) R. = (n°-32) C. n° C.=(9/5 n° + 32) F. = 4/5 n° R. n° R.=(9/4 n° + 32) F. = 5/4 n° C. As the freezing point of water is at 32° F., corresponding to 0° C. and 0° R., 32 must be deducted from the Fahrenheit degrees when these are converted into C. or R. degrees. Likewise, to C. or R. degrees converted into F. degrees 32 must be added. The fractions 4/9 and 5/9 and their reciprocals are obtained thus:

Jan 5, 1913

By N. V. Hansell

l. INTRODUCTION. THE last few years have shown an increasing interest in the subject of beneficiating iron-ores -in all iron-producing countries. In the United States, this movement has been slower than in certain parts of Europe, for the obvious reason that the abundance and relative cheapness of the Lake Superior iron ores has hindered the development of enterprises for the preparation of low-grade ores. Gradually, however, conditions have changed. The world's consumption of iron is increasing enormously. Being in 1900 about 40,000,000 tons, in 1910 ii was already 60,000000; and there is no reason to doubt that for the near future the increase in iron-consumption will continue at the same rapid rate, especially with, the development of China, certain parts of Africa, and other regions which have hardly been touched as yet by modern industrialism. It is. therefore, not surprising that apprehension is felt that the known available iron-ore resources of the world are gradually being depleted. Signs of this feeling are the recent investigation, under the direction of the U. S. Geological Survey, of the iron-ore resources of the United States, and the estimate presented to the last International Geological Congress, at Stockholm, Sweden, of the iron-ore resources of the world. These investigations have emphasized the fact that the known high-grade ore-deposits are limited in extent, and will, at a not distant future, be exhausted, compelling the iron industry to depend for raw material on the enormous deposits of low-grade ores which are distributed over almost all the world. The discovery of new deposits of high-grade ore, in countries not yet thoroughly explored, will not materially change this prospect. Of course, the part which such new deposits will play in the future cannot be forecast. The difficulty and cost of transportation will probably exclude many of them from use at the present centers of the iron industry.

May 1, 1912

By John O. Farmer

The wire-line tubing perforator is a mechanically operated tool that is run on an ordinary steel measuring line into the tubing of a well, under pressure, to drive into the wall of the tubing, and securely lock in place, a tapered, cylindrical insert containing an orifice. Use of the perforator obviates the necessity of pulling and rerunning the tubing to install jet collars or flow valves, reduces the cost, and simplifies the task, of placing an oil well on gas-lift operation. More important, however, is the use of the tool with a removable check valve and stop, to provide a means of washing drilling mud from the annulus between the tubing and casing, and to complete the well for gas lift operation without exposing the producing formation to the mud column and without moving the tubing string. This paper discusses the origin, development, and mechanics of the wire-line perforator, the various purposes for which the tool was designed, and the method of selecting orifice sizes for any depth, and gives the results obtained thus far in practical application. Origin and Development Several years ago, a tool that could be lowered on an ordinary steel measuring line into the tubing of a well under pressure was designed and constructed for the purpose of punching a hole in the tubing walls above a shale bridge that had completely plugged the tubing of a well in the Long Lake field, East Texas. The well was in a low, swampy area, which excessive rainfall had caused to be in- accessible by car or truck for about four months. The only equipment at the well site consisted of an ordinary steel wire line that had been carried there to measure the depth of the bridge. Since a pulling unit could not be moved to the well site, and as the pressure on the casing was 2100 lb. per sq. in., it became apparent that the only way out of the predicament was to make a perforating tool that could be lowered into the tubing on a measuring line and operated under Pressure. Thus, the first wire-line tubing perforator was designed and built as an expedient, and was not used extensively until it had been redesigned to meet more frequent and increasingly urgent needs. Until recently, it was necessary to pull the tubing to install jet collars or flow the when a well was to be placed On gas lift. Because most companies either maintained or had access to pulling units and crews for this work, little or no thought had been given to eliminating or even simplifying this task. When the manpower and steel shortage became so acute, however, many operators suddenly found themselves without facilities to equip their wells for gas lifting. The wireline tubing perforator already had been tried and proved successful, therefore operators immediately requested its use to punch gas-jet holes in the tubing, to eliminate the pulling and running of tubing strings. The first deficiency revealed by more general use of the perforator lay in the inability to regulate the size of the hole punched through the tubing. The size could not be controlled to any degree of

Jan 1, 1946

By John O. Farmer

The wire-line tubing perforator is a mechanically operated tool that is run on an ordinary steel measuring line into the tubing of a well, under pressure, to drive into the wall of the tubing, and securely lock in place, a tapered, cylindrical insert containing an orifice. Use of the perforator obviates the necessity of pulling and rerunning the tubing to install jet collars or flow valves, reduces the cost, and simplifies the task, of placing an oil well on gas-lift operation. More important, however, is the use of the tool with a removable check valve and stop, to provide a means of washing drilling mud from the annulus between the tubing and casing, and to complete the well for gas lift operation without exposing the producing formation to the mud column and without moving the tubing string. This paper discusses the origin, development, and mechanics of the wire-line perforator, the various purposes for which the tool was designed, and the method of selecting orifice sizes for any depth, and gives the results obtained thus far in practical application. Origin and Development Several years ago, a tool that could be lowered on an ordinary steel measuring line into the tubing of a well under pressure was designed and constructed for the purpose of punching a hole in the tubing walls above a shale bridge that had completely plugged the tubing of a well in the Long Lake field, East Texas. The well was in a low, swampy area, which excessive rainfall had caused to be in- accessible by car or truck for about four months. The only equipment at the well site consisted of an ordinary steel wire line that had been carried there to measure the depth of the bridge. Since a pulling unit could not be moved to the well site, and as the pressure on the casing was 2100 lb. per sq. in., it became apparent that the only way out of the predicament was to make a perforating tool that could be lowered into the tubing on a measuring line and operated under Pressure. Thus, the first wire-line tubing perforator was designed and built as an expedient, and was not used extensively until it had been redesigned to meet more frequent and increasingly urgent needs. Until recently, it was necessary to pull the tubing to install jet collars or flow the when a well was to be placed On gas lift. Because most companies either maintained or had access to pulling units and crews for this work, little or no thought had been given to eliminating or even simplifying this task. When the manpower and steel shortage became so acute, however, many operators suddenly found themselves without facilities to equip their wells for gas lifting. The wireline tubing perforator already had been tried and proved successful, therefore operators immediately requested its use to punch gas-jet holes in the tubing, to eliminate the pulling and running of tubing strings. The first deficiency revealed by more general use of the perforator lay in the inability to regulate the size of the hole punched through the tubing. The size could not be controlled to any degree of

Jan 1, 1946

By Carl Allen

INTRODUCTION IN any discussion of mining one is repeatedly confronted with the difficulty of dealing with so many variable conditions. It is not an exact science and in the choice of a method each varying factor has a certain weight, which, in many cases, experience alone can determine. In mathematical terms, it is a function of many variables. A discussion of mining also loses much of its value unless, costs are considered, because the expectation of profit is the only excuse for carrying on mining at all. As conditions vary they cause fluctuations in cost and there are few operations to which a definite cost can be assigned. The character of the ore may make it difficult to drill, yet because of the ease with which it breaks the total cost of drilling and blasting may be low. In preparing this article the attempt has been, not to cover the whole field of mining, but to describe the different methods of stoping and mining which have distinct principles. In addition to this an effort has been made to show the advantage of dissecting the methods into their detailed operations and applying to these a mathematical study as an aid to the judgment in determining which is the best method to adopt, or in attempting to reduce the cost of a method already in use. Methods of mining include stoping, caving, and various methods of working large deposits which, in addition to the method of actually breaking the ore, require elaborate and definite plans of, development of the orebody. The ordinary methods of stoping are too familiar to all for any elaborate discussion, but it has seemed advisable to review the subject and give the principal advantages' and disadvantages of the different methods.

Jan 8, 1914

By G. W. Imholz

A number of interesting wells were drilled in north central Texas during 1940. The Shell Oil Company's Smith well in scc. 143, block I, H. and T. C. survey, Stonewall County, was completed for an initial production of 581 bbl. per day from the Mississippian limestone, with a total depth of 6065 ft. The same company's Patterson well, sec. 393, block D. H. and T. C. survey, Stonewall County, tested the Ellenburger limestone and was abandoned as a dry hole with a total depth of 6760 feet. In Nolan County the Tex-Harvey Oil Co. drilled a well in sec. 43, near the Tipton well, which was completed as a small producer in the Strawn section. The Tex-Harvey well tested this producing horizon but was abandoned as a dry hole with a total depth of 5210 feet. The Montour-Haggart well, sec. 184, block 2, H. and T. C. survey, Fisher County, tested the Strawn and was abandoned with a total depth of 5664 feet. The Georgian Oil Company's Blach, sec. 309, T. R. and L.. Shackelford County, encountered the top of the Ellenburger limestone at 4725 ft. After being plugged back to 3915 It. from a total depth of 4825 ft., the well tested 10 bbl, of oil per day and 300 bbl. of water. The W. I. Sothern No. 2 Carlisle well in sec. 293 was deepened to the Cambrian. The top of the Ellenburger was encountered at 6540 fcet. A wildcat well in Fisher County, the E. A. Stephenson-Maberry, apparently opened a new pool when the well encountered sand from 3298 lo 3302 ft. and was completed for 50 bbl. per day in the Cook sand horizon. In Jones County, the King Oil Company's Olsen well, sec. 158, B. B. B. and C. survey, extended the Avoca-Olander pool. The well was completed for 263 bbl. in 8 1/2 hr. from the Palo Pinto limestone, from 3298 to 3302 ft. Ungren-Frazier extended the Akard pool with No. I Akard, in the D. 'T. Bruce survey. The well was completed for 83 bbl. per day from the Cook sand, encountered from 2109 to 2126 feet.

Jan 1, 1941

By G. W. Imholz

A number of interesting wells were drilled in north central Texas during 1940. The Shell Oil Company's Smith well in scc. 143, block I, H. and T. C. survey, Stonewall County, was completed for an initial production of 581 bbl. per day from the Mississippian limestone, with a total depth of 6065 ft. The same company's Patterson well, sec. 393, block D. H. and T. C. survey, Stonewall County, tested the Ellenburger limestone and was abandoned as a dry hole with a total depth of 6760 feet. In Nolan County the Tex-Harvey Oil Co. drilled a well in sec. 43, near the Tipton well, which was completed as a small producer in the Strawn section. The Tex-Harvey well tested this producing horizon but was abandoned as a dry hole with a total depth of 5210 feet. The Montour-Haggart well, sec. 184, block 2, H. and T. C. survey, Fisher County, tested the Strawn and was abandoned with a total depth of 5664 feet. The Georgian Oil Company's Blach, sec. 309, T. R. and L.. Shackelford County, encountered the top of the Ellenburger limestone at 4725 ft. After being plugged back to 3915 It. from a total depth of 4825 ft., the well tested 10 bbl, of oil per day and 300 bbl. of water. The W. I. Sothern No. 2 Carlisle well in sec. 293 was deepened to the Cambrian. The top of the Ellenburger was encountered at 6540 fcet. A wildcat well in Fisher County, the E. A. Stephenson-Maberry, apparently opened a new pool when the well encountered sand from 3298 lo 3302 ft. and was completed for 50 bbl. per day in the Cook sand horizon. In Jones County, the King Oil Company's Olsen well, sec. 158, B. B. B. and C. survey, extended the Avoca-Olander pool. The well was completed for 263 bbl. in 8 1/2 hr. from the Palo Pinto limestone, from 3298 to 3302 ft. Ungren-Frazier extended the Akard pool with No. I Akard, in the D. 'T. Bruce survey. The well was completed for 83 bbl. per day from the Cook sand, encountered from 2109 to 2126 feet.

Jan 1, 1941

By Frederick Prime

The Great or Cumberland Valley, which (under a variety of names) extends from Canada, through Vermont, Massachusetts, Connecticut, New York, Pennsylvania, Maryland, Virginia, and East Tennessee, to Alabama, is composed in part of limestones lying immediately above the Potsdam sandstone. Geologically, they belong to the era between the Potsdam and Trenton, and are commonly termed Calciferous. A peculiarity of these limestones is their great richness in limonite or brown hematite ores, which form a large part of the charges of the many blast-furnaces situated on their outcrops. The mines from which the ores are obtained are (properly speaking) only pits or quarries, from which 'the ore is extracted by means of picks or shovels, powder being rarely employed. The ore does not occur casually at any point in the limestone, but forms regular lines, following apparently the outcrops of certain beds. In Lehigh County, Penn., where 1 have been engaged on the Geological Survey of the State, during the past season, there are three or four of these lines. During the progress of the survey I was much struck by the fact that the two most important and promising lines of outcrop were, one at the base of the crystalline schists (forming the South or Lehigh Mountain), and overlying the Potsdam sandstone conformably; the other, near the line of junction of the calciferous limestone with the slates of the Cincinnati epoch. The mines along these two lines, following the topography of the country, were in place, richer and more permanent than those of the belts between, which were generally leaner. A peculiarity of these two lines of outcrop, and one to which I particularly desire to draw attention, is the occurrence of what I at first mistook for a highly altered slaty limestone, but which subsequent analysis proved to consist in great part of damourite (hydrated potash mica). The following are analyses of this damourite slate: I. From Fogelsville, Lehigh County, within a few hundred feet of the contact of limestone and slate, by Dr. F. A. Genth. 11. From Hensingerville, Lehigh County, within 300 feet of gneiss, by Mr. Sydney Castle, of the University of Pennsylvania. 111. From Allentown, Lehigh County, within 150 feet of con

By Dr. O’Neil Thomas J., Donald W. Gentry

"If you can hold a board of cross directors In happiness against their gauzy schemes; If you can dodge the wrath of the electors Till dividends will flow as in their dreams; If you can make a mine pay from the grass roots No matter what the time or place or year; Then on my soul until the final blast shoots We'll add the title "MINING" when we call you "ENGINEER. " -From Wayne Darlington, "The Mining Engineer, " The Engineering and Mining Journal, Vol. 98, Sept. 26, 1914, p. 587. REASONS FOR THIS CHAPTER Up to this point in the book the material presented has addressed the fundamental parameters associated with the evaluation of mining ventures and other investment alternatives. The procedures and techniques illustrated represent the basic approach to project evaluation, particularly when considering the normal engineering economic analysis of investment proposals. The evaluation procedure is complicated, however, when dealing specifically with mining-related investment proposals. These complicating factors are invariably directly related to the many special characteristics of the mining industry. Many of these special features such as tax policies, revenue and cost estimation, and ore reserves have been addressed in previous chapters. In addition to the many special features of mining which directly impact, in a quantitative manner, the various line items in the pro forma income statements of a cash flow analysis, other features of mining affect evaluation procedures in a more general manner. The main purpose of this chapter, then, is to provide an exposition of some of these more qualitative factors. We hope this will enable the reader to recognize these factors in mine evaluation practice and to make suitable adjustments in his or her analysis.

Jan 1, 1984

By W. O. Crosby

INTRODUCTION. THE crystalline belt of the Atlantic Seaboard, south of New York, attains its maximum breadth of 220 miles on the northern border of North Carolina; and in this State it is most widely characterized by the occurrence of gold in workable deposits. Half a dozen auriferous belts have been recognized by Nitze and Hanna.1 These are, in the main, coincident in position and trend with the NE.-SW. zones of metamorphic slates and schists, which, more than any other feature, give character to the geological map of North Carolina. The central gold-belts, accompanying the main zone of slates and associated igneous rocks, are much the more important and persistent, and may be regarded as continuous northward across Virginia and southward into South Carolina. Tile eastern belt, on the other band, is the shortest and, economically, one of the least important. Its extreme length does not exceed 25 miles, the narrow band of slaty rocks to which it belongs passing, both NE. and SW., beneath the coastal-plain formations. But, although limited in area and production, this belt is, perhaps, comparable with the central belts or any part of the sea-board crystallines in the variety of conditions under which the gold occurs. It lies chiefly in the NE. part of Franklin county and the NW. part of Nash county, on the watershed of Fishing creek and other tributaries of Tar river. The elevation is between 400 and 500 ft. ; and the Tertiary peneplain has here an exceptionally perfect development, the reliefs separating the slightly incised stream-courses consisting of broad, flat-topped peneplain remnants, bounded by gentle lateral slopes.

Mar 1, 1908

By W. C. Roberts-Austin

The subject with which the Council of the American Institute of Mining Engineers has entrusted me is one of much interest. It has been so admirably treated in America by Prof. Carl Barus* that I should have hesitated to deal with it had not the adoption of pyrometric methods in England recently occupied much attention, especially in relation to metallurgical industries and research. I shall endeavor to show what is the present state of our knowledge of practical pyrometry by briefly tracing the history of the efforts which have been made to measure high temperatures. This paper will, therefore, be limited to the consideration of those forms of appliance which have either marked distinct stages of advance, or have remained in use with more or less modification through a considerable range of time. The earliest pyrometers were essentially thermoscopes, and although their graduation presented great difficulties, their importance as affording a means for the measurement of high temperatures has been recognized for centuries. It would be difficult to illustrate this better than by a brief record of the testimony which has from time to time been offered by those who have had to apply the heat of furnaces in research or in industry, and it is mainly for the sake of the light incidentally thrown on the progress of both that the following historical notes are offered. In the eighth century, Geber, the chemist, wrote a treatise on furnaces, and showed that he was familiar with many and varied means of applying heat; but he points to the difficulties that are met with in conducting operations at high temperatures, which he attributed to inability to measure heat, his actual words being: " sed quoniam non est res ignis, quae mensuari possit." t

Jan 1, 1894