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By D. H. Davis, I. Fatt

Oil bearing rocks, usually found at depths of 2,000 to 10,000 it, are elastically deformed by overburden pressure. Although the change in porosity with pressure in a number of example rock.: has been shown to be small, it was thought that overburden pressure might have a significant effect on permeability. This note presents results of an investigation to determine the magnitude of the change in permeabilty with pressure. In routine core analysis permeabilities are measured on rock samples which are not under overburden pressure. If permeablity measured in this way differs from permeabilities measured under overburden pressure, a systematic error is introduced into well productivity calculations. The experiments described in this report were made to determine the magnitude of the change and thus to give an estimate of the error introduced into the calculations. The error introduced by the neglect of the change in permeability when overburden pressure is removed may account for part of the difference between well productivity calculated from core analysis and the actual well productivity. The results obtained in this investigation have only quali-tative significance because of the difficulty in reproducing in the laboratory the stress conditions on the rock buried in the earth. The assumption which is usually made is that the rocks in the earth are under a uniform pressure equal to the weight per unit area of the vertical overburden column from the rock in question to the surface of the earth less the pressure of the liquid in the pores of the rock. For an overburden consisting of sandstones and shales (of assumed average specific gravity of 2.3) and for a liquid pressure equal to the pressure in a salt water column (of specific gravity 1.0) reaching from the rock to the surface, the resulting net pressure on the rock is approximately 0.56 psi per ft of depth. EXPERIMENTAL METHOD Clean, dry sandstone core plugs one in. in diameter and about three in. long were mounted in a copper foil jacket as shown in Fig. 3 or molded in a Lucite jacket as shown in Fig. 4. All cores except those labeled "2" in Fig. 1 and "8" in Fig. 2 were measured in the copper foil jacket. Cores "2" and "8" were measured in the Lucite jacket. The jacketed core was placed in a high pressure hydraulic bomb in which the liquid pressure outside the jacket could be raised to 15,000 psi. Flow lines from the core were brought out of the bomb through special fittings in the bomh head and connected to a laboratory type gas permeameter. Measurements were made with nitrogen gas; the maximum mean gas pressure in the core was 16.1 psia. RESULTS The specific permeability of sandstone decreases with in. crease in overburden pressure. Most of the decrease takes place over the range of zero to 3,000 psi overburden pressure. If the net pressure on the rock is assumed to be 0.56 psi per ft of depth as discussed above, 3,000 psi of overburden pressure is equivalent to about 5,000 ft of overburden. At 3,000 psi overburden pressure, the permeability of the eight sandstone core samples tested ranged from 59 to 89 per cent of the permeability without overburden pressure. Figs. 1 and 2 show the permeability reduction as a function of overburden pressure. The permeability of the eight cores without overburden pressure ranged from 4.35 md to 632 md; these permeabilities are listed in Figs. 1 and 2. REFERENCES 1. Carpenter and Spencer: "Measurements of Compressibility of Consolidated Oil Bearing Sands," U. S. Bureau of Mines, R.I. 3450, (1940). * * *

Jan 1, 1952

By J. A. Elias, A. J. Heckler

A simplified method is described for the prepauatior~ of comnposite samples for determination of one quadrant of an X-ray pole figure of a sheet material by the Schulz reflection method. Other special conzposite sampling methods were used to investigate specific areas of the pole figures. Plotting nets for these sampling plans were drawn by a computer. Step-scanning techniques were used to obtain detailed information about specific regions of a pole figure. Satisfactory pole figures were obtained for large-grained (0.5 to 1 in. diam) sheet materials. COMPOSITE sampling techniques for preparing one quadrant of an X-ray pole figure have been reported by a number of authors.'-5 All of these methods are similar in that they use a composite sample prepared by stacking and holding together coupons cut from a sheet material. The schulze reflection technique is applicable to the composite sample so that only minor corrections are needed for defocusing and absorption effects. Also, a relatively large area of a sheet is sampled through the use of multiple cross sectional pieces. In general, sampling methods necessary to obtain a composite-type specimen have been formidable enough to discourage their use in routine pole figure determinations. This paper presents a versatile sampling technique which is simpler than those previously described along with an accurate method for obtaining stereographic plotting nets for any orientation of a composite specimen surface. A step-scanning technique is used to obtain more quantitative determinations of specific regions in pole figures, and the composite technique is satisfactorily applied to determine pole figures of very large grained sheet materials. REVIEW OF PREVIOUS TECHNIQUES Mueller and ~nott' first proposed a technique for obtaining one complete quadrant of an X-ray pole figure by using a sheet sample and six different composite samples in which the individual coupons were aligned and held together by two types of jigs. Data from the seven different samples were overlapped to obtain a single quadrant. ~eieran~ and Lopata and ~ula~ obtained a complete quadrant of a pole figure from a single sample prepared by forming a cube from coupons cut from a sheet. These coupons were bonded together using an epoxy cement, and a cut was made at 54.7 deg to the normal, transverse, and rolling directions of the sheet, Fig. I. The normal direction of the cut face projects into one quadrant of a stereographic projection at equal angles to the three principal orthogonal reference directions mentioned above. X-ray reflection data obtained along a spiral path in physical space could then be plotted on a stereographic net offset 54.7 deg from the normal, as shown in Fig. 2. A rotation about an axis representing the surface normal is designated as a, and a rotation about an axis lying in the plane of the surface is 4. From Fig. 2 it is apparent that a tilting angle of no more than 55 deg @ is necessary to obtain the complete quadrant. ~eber~ devised an improved sampling technique by cutting coupons 45 deg to the rolling direction of a sheet, stacking and bonding these with an epoxy cement at an angle of 54.7 deg to a reference plane, and finally grinding and lapping a flat specimen surface parallel to this plane. An important consideration of this technique and that of Lopata and ~ula~ is variation in the diffracting power of the specimen surface due to the bonding medium. While any composite-type sample will have some such variation due to boundaries between coupons, the problem can be minimized by elimination of the bonding medium and by avoiding prolonged etching times which could lead to significant inter lame llar attack of the coupon faces. EXPERIMENTAL TECHNIQUE We were working concurrently though independently on a technique similar to ~eber's,' but which does not

Jan 1, 1968

By A. G. Paithankar, G. B. Misra

Although certain physical mechanical properties of rocks have been claimed to give an estimate of penetration rate in percussive drilling, the authors' work shows that the correlation of penetration rate with individual rock properties is Poor. The authors have developed a good correlation between penetration rate and a set of rock properties but the relation is complex. Energy per unit volume has been used as a measure of penetration rate in percussive drilling by Hustrulid and Fairhurst; however, their test setup is large wing a full size drill bit. The authors determined the minimum energy for unit volume Ev min for any rock at the optimum index angle in a simple laboratory drop tester wing a sharp microbit with a tip angle of ll0°. This Ev min has been found to correlate well with penetration rate obtained in controlled laboratory drilling in different rocks for different stages of bit wear. A comprehensive relation has been developed between penetration rate and Ev min.

Jan 1, 1981

The ability of activated charcoal or carbon to adsorb complex metal ions has been recognized for many years, but it wasn't until the late 1940s and early 1950s that attempts were made to employ carbon-In-Pulp or C. I. P. processing to the recovery of gold. Early plants using the process were those at the Golden Cycle in Cripple Creek, Colorado, the Getchell Mine near Golconda, Nevada, and at the Idria Mine in Honduras. Recovery of the carbon from the pulp was done by screening or flotation, and recovery of gold from the carbon was done by burning the carbon (a very difficult task) or by sending it to a smelter. Unfortunately at the time, the price of gold was still fixed at $3-5 per ounce and labor costs were rising to the point where these mines were no longer able to operate. Consequently, C. I. P. treatment was temporarily forgotten. In the early 1970s, however, Homestake Mining Company at Lead, South Dakota, were being forced by environmental regulations to discontinue the use of mercury for amalgamation in their 7,500 ton per day plant, and at the same time were encountering high labor costs in the slime circuit of the plant, where over 2,000 tons of slimes were filtered each day in Merrill plate and frame filter presses. Shortly before that, researchers of the United States Bureau of Mines had developed the caustic -cyanide method of stripping gold from activated carbon and an electrolytic cell (now known as the Zadra cell) to recover gold from the carbon strip liquor. Homestake and the United States Bureau of Mines then jointly operated a C. I. P. pilot plant at Lead. Results were immediately favorable and a 2,400 ton per day C. I. P. plant was then built to treat the slime fraction of the Homestake ore. (See Au and Ag Cyanidation Plant Practice, Volume I, SME of AIME, 1975. Later, Homestake built a second plant at Creede, Colorado, to treat the slime fraction of the tailings from a silver-lead flotation plant. Next was Duval Corporation's 3,000 ton per day C. I. P. plant at Battle Mountain, Nevada. Both of these latter plants are described in this volume. C. I. P. operations under construction at the time of this writing are as follows: Pinson Mining Co. , Nevada Gold Freeport Gold Company, Nevada Gold Compania Minera El Indio, Chile. Silver and Gold

Jan 1, 1981

By Thos Gibson

THE object of taxation is the raising of a revenue. Unless a tax accomplishes this, it is a failure. The right to take for public purposes a part of the moneys obtained from the carrying on of private enterprises is an attribute possessed only by a lawful government, and may indeed he called the supreme attribute of government. In free, democratic communities this power must of necessity rest upon the consent of the governed. Power implies obligation, hence it is obviously the duty of a government, in framing a system of taxation, to provide one which, while effective in producing a revenue, is also just and impartial. It will be conceded that mines and mining property ought to bear a fair share of the public expenditure. The question is, upon what basis taxation should proceed. Two separate taxing principles are usually contended for: Taxation should be proportionate to the benefits received by the person or property taxed; taxation should be based on ability to pay. A third is sometimes added, taxation should have reference to the extent and value of the natural resources enjoyed. As applied to mining taxation, it is pointed out by those who support the first mentioned basis that, mines being usually situated in rocky and hence sparsely peopled regions, mining companies are frequently obliged to construct roads, railways, telegraph and telephone lines, schools, water and sewerage systems, and many other amenities and conveniences of civilization, the cost of which in regions better suited for agriculture and consequently more thickly populated, has either been defrayed locally, or can be spread over a sufficiently large taxable group of people to materially lighten the financial burden on the mine. The mining com¬pany, it is argued, having made these outlays, should receive credit for, them and be relieved of taxation to a corresponding extent. There may be some force in this contention, but the situation is capable of relief without attempting to place taxation upon so unworkable a basis as the value of benefits received. Who is to be the judge of these benefits, and how are they to be valued? The very existence of a mining company and its ability to carry on business in peace and security, depend on the prevalence of law and order, which is a result of good government. The state provides protection against violence, and courts of law for

Jan 4, 1919

By Ralph Arnold

IN OPENING the symposium under the auspices of the Petroleum and Gas Committee of the American Institute of Mining and Metallurgical Engineers, I wish to call to your attention the following, among other subjects, which it is hoped may receive proper attention: 1. The recording of as accurate an appraisal of the oil possibilities of the various countries as is possible, with information as to the immediate availability of their supply. 2. The development of further support for the move-ment to bring about active cooperation among Ameri-can oil companies in their foreign exploration and development work. 3. The furtherance of the efforts of the industry in securing governmental assistance in foreign oil develop-ment: (a) along the lines of a modification of our domestic oil policy, so that we can go to foreign coun-tries and consistently ask fair treatment as to royalties and bonuses; (b) by a closer cooperation between the State and Commerce Departments and the oil industry. 4. The calling of attention to the unjustifiably drastic action of the price-fixing group of the oil industry during the last year or so, with the hope that it will use gentler methods in the future. None of these subjects are new, and some of them have been discussed before various organizations for years. Our justification for again bringing them forward is the hope that by everlastingly harping on them the industry, the Government, and the people who shape the destinies of this country may some time, some how, realize their importance and take effective constructive action.

Jan 6, 1922

By Charles Catlett

The terms " developed " and " undeveloped " are necessarily relative and cover a wide range; but the latter is here applied to cases in which the information at hand falls short of a clear demonstration of values, and conclusions must be reached frorn a study of the geological conditions of the particular deposit, interpreted in the light of similar and closely-related deposits. Such an inquiry might be characterized as an effort to reach reliable conclusions from insufficient data. But the engineer

Jan 1, 1909

By S. E. Bretherton

Mr. AllaW Gibb, of Mount Perry, Queensland, Australia, in an interesting and instructive paper,* describes fully the great difficulties metallurgists encounter in seeking to produce marketable copper by smelting refractory ores containing arsenic, antimony and bismuth. After reading this description, I prepared a paper for the Institute, which was, however, through a misunderstanding on my part, published in the San Francisco Mining and S'cie~ztiJic Press of April 4, 1903, after its acceptance by the Council, and without credit to the Institute. Consequently, it cannot be reprinted for the Transactions of the Institute; and I can only here summarize its contents and conclusions, referring the reader to the article above named for further particulars. In that article I omitted the col~sideration of bismuth, which we do not encounter in our smelting at Val Verde, and added lead and zinc, which Mr. Gibb had not discussed; and I undertook to shorn, by the record of a year's practice of the Val Verde Copper Co., Arizona, that copper-ores containing arsenic, antimony, lead and zinc may be successfully smelted, without preliminary roasting, in an ordinary blast-furnace with hotblast, making a normal slag, such as one would aim to make under ordinary conditions with cold-blast, so as to produce a marketable matte, containing not less than 45 per cent. of copper, free from arsenic and antimony, and below the limit in lead and zinc penalized by the refineries.

Jan 1, 1904

By Carlton Beal

This paper presents useful charts for conversion of various viscosimeter units into centipoises and graphically summarizes published investigations of the viscosity of air, water and natural gas at high temperatures and pressures. Where possible, charts and correlations were constructed to cover a range of temperature (60°F. to 300°F.) and pressure (14.7 lb. per sq. in. abs. to 8000 lb. per sq. in. gauge) encountered in oil fields. Correlation charts, for the purpose of predicting crude oil viscosity and solubility behavior at oil field temperatures and pressures, were constructed from an analysis and correlation of 1332 viscosity and solubility observations from 953 crude oil samples taken from 747 oil fields. Of these fields, 501 are in the United States, including 75 in California. Of the 1332 observations, 1215 were viscosity values, including 786 of gas-free crude oil, 351 of oil saturated with gas, and 78 under-saturated with gas at pressures above the bubble point. Results show that crude oil viscosity at various reservoir conditions can be predicted with average deviations varying from 24.2 per cent for gas-free crude oil to as little as 2.7 per cent for undersaturated crude oil "above the bubble point." The solubility of crude oil may be predicted from oil gravity and saturation pressure with an average deviation of 22.0 per cent from observed values. In conclusion, it is shown that the viscosity of a gas and gas-saturated crude oil may be predicted within the accuracy of most reservoir computations. Viscosity is a measure of flow resistance; common units are in centipoises (cp.). The object of this report is to present conversion charts and simplified 'correlation charts showing the viscosity behavior of air, water, gas and crude oil and gas-saturated crude oil under oil field temperatures and pressures, which have been known to be as high as 300°F. and 8000 Ib. per sq. in. gauge under subsurface conditions. The viscosity of a liquid or gas is important because it is a measure of its fluidity, or its ability to flow through pipe lines or oil sands. Viscosity of air has become important because it is being used in secondaryl,2 recovery projects. The viscosity of natural gas and water at reservoir conditions is useful because they are almost universally associated and produced with crude oil. The viscosity of gas-saturated crude oil at reservoir pressures and tem peratures is of particular value in making estimates of oil reserves3 and rate of oil recovery from flush pools when production decline data are limited. Instruments Used to MeasuRe Viscosity There are many types of viscosimeters,4 and the instruments most commonly used to measure the atmospheric viscosity of liquids at moderate temperatures and their practical working ranges have been deScribed5,6 in detail. Fig. I and Fig. 2 are viscosity conversion charts which have

Jan 1, 1946

By Carlton Beal

This paper presents useful charts for conversion of various viscosimeter units into centipoises and graphically summarizes published investigations of the viscosity of air, water and natural gas at high temperatures and pressures. Where possible, charts and correlations were constructed to cover a range of temperature (60°F. to 300°F.) and pressure (14.7 lb. per sq. in. abs. to 8000 lb. per sq. in. gauge) encountered in oil fields. Correlation charts, for the purpose of predicting crude oil viscosity and solubility behavior at oil field temperatures and pressures, were constructed from an analysis and correlation of 1332 viscosity and solubility observations from 953 crude oil samples taken from 747 oil fields. Of these fields, 501 are in the United States, including 75 in California. Of the 1332 observations, 1215 were viscosity values, including 786 of gas-free crude oil, 351 of oil saturated with gas, and 78 under-saturated with gas at pressures above the bubble point. Results show that crude oil viscosity at various reservoir conditions can be predicted with average deviations varying from 24.2 per cent for gas-free crude oil to as little as 2.7 per cent for undersaturated crude oil "above the bubble point." The solubility of crude oil may be predicted from oil gravity and saturation pressure with an average deviation of 22.0 per cent from observed values. In conclusion, it is shown that the viscosity of a gas and gas-saturated crude oil may be predicted within the accuracy of most reservoir computations. Viscosity is a measure of flow resistance; common units are in centipoises (cp.). The object of this report is to present conversion charts and simplified 'correlation charts showing the viscosity behavior of air, water, gas and crude oil and gas-saturated crude oil under oil field temperatures and pressures, which have been known to be as high as 300°F. and 8000 Ib. per sq. in. gauge under subsurface conditions. The viscosity of a liquid or gas is important because it is a measure of its fluidity, or its ability to flow through pipe lines or oil sands. Viscosity of air has become important because it is being used in secondaryl,2 recovery projects. The viscosity of natural gas and water at reservoir conditions is useful because they are almost universally associated and produced with crude oil. The viscosity of gas-saturated crude oil at reservoir pressures and tem peratures is of particular value in making estimates of oil reserves3 and rate of oil recovery from flush pools when production decline data are limited. Instruments Used to MeasuRe Viscosity There are many types of viscosimeters,4 and the instruments most commonly used to measure the atmospheric viscosity of liquids at moderate temperatures and their practical working ranges have been deScribed5,6 in detail. Fig. I and Fig. 2 are viscosity conversion charts which have

Jan 1, 1946

By S. K. Nicol, A. R. Swanson, J. C. Day

Addition of oil to a suspension of hydrophobic coal particles can influence its dewatering characteristics. An agglomeration process occurs in which coal particles are held together by negative capillary pressure at particle/oil/water contacts. Consequently, the units round which flow can occur are enlarged and this improves dewatering parameters such as drainage rate, solids recovery, and equilibrium moisture content. This paper discusses processes which attempt to use this principle, in terms of metallurgical and economic efficiency. The discussion is augmented by results of recent experiments on the effect of oil addition to centrifuges and vacuum filters.

Jan 1, 1980

Discussion of the paper of THEODORE P. HOLT, presented at the Salt Lake meeting August, 1914, and printed in Bulletin No. 91, July, 1914, pp. 1699 to 1708. F. S. SCHMIDT, Salt Lake City, Utah.-Any furnace that can make a chloridizing roast to yield an extraction of 92 to 93 per cent. and do this at a cost of less than 24c. per ton in a 10-ton unit opens great possibilities for the treatment of certain classes of ores. This cost does not include the salt and will be reduced to about 16 1/2c. per ton in the 35-ton furnace which are now being designed. On a trial run the roaster treated 9.6 ton: of Ontario stope fillings crushed to pass a ¼ -in. opening. The ore is well adapted to chlorination with the exception of insufficient sulphur and occasional days of high lime, but is not adapted to any other process The following is an analysis of the crude ore: Ag, 9.52; Au, 0.029 oz. Pb, 0.71; Cu, 0.11; SiO, 79.4; Zn, 0.57; S, 1.00; Fe, 7.9; Mn, 0.89 CaO, 1.20 per cent. The composition of the mix was: Per Cent. Dry crude ore : 83.4 Moisture 4.4 Salt 8.3 Coal dust 2.3 Pyrite, 70 per cent. pure 1.6

Jan 11, 1914

By H. F. Yancey, O. L. Furse

Although usually coal is screened with punched plate screens having round-hole perforations, there has been an increasing use of wire-cloth screens with square apertures, especially at pneumatic coal-cleaning plants and at other plants that use vibrating screens. It is therefore desirable to establish a relationship between round-hole and square-hole screens for use not only in experimental investigations of coal-preparation problems, but also for use in commercial operations. This need is apparent whenever it is necessary to substitute wire cloth for punched plate and still retain the familiar trade-size product. Although similar work probably has been done by industrial organizations concerned with the screen sizing of coal, the only recorded study of the subject other than the one described herein of which the authors are aware is that of Roesler,1 who screen-sized two samples of limestone and two of zinc concentrates crushed to pass 1/2 in. with a set of square and round-hole screens and found the ratio to be 1:1.23. Procedure In the course of a study of various methods for determining the friability of coal,2 it was necessary to screen-size the products of a series of friability tests of three different coals with both round-hole and square-hole screens. The coals used were from the Roslyn No. 3 and the Bayne mines in Washington and the Rolapp mine in Utah. Twenty 25-lb. samples of each of these three coals at 3 to 2 1/2 in. round-hole size were dropped from a height of 10 ft. to a concrete floor, and then screened with

Jan 1, 1934

By P. Breidt, E. S. Greiner

THIS note reports a determination of the melting point of germanium, and the liquidus of the Ge-Ga alloys; lattice constants of the a phase are given. The alloys were prepared by melting germanium (>20 ohm-cm resistivity) and gallium (99.6 pct) in evacuated silica tubes. The materials (50 to 70 g) were heated at 1000°C, held in the liquid state for about ¾ hr, and then cooled rapidly in the tubes. Points on the liquidus were obtained by thermal analysis which consisted of obtaining time-temperature data during heating and cooling the materials in high purity graphite crucibles and a helium at- mosphere. Temperatures were determined with a Pt—Pt-Rh thermocouple protected by a silica sheath. The couple was calibrated against a National Bureau of Standards calibrated couple and also against the freezing points of copper, silver, aluminum, and the 28.1 wt pct Cu, 71.9 wt pct Ag alloy eutectic. The samples for X-ray analysis were prepared by heating small pieces of the ingots in evacuated glass or quartz tubes at temperatures between 600" and 900°C for periods ranging from 2 hr to 22 days, periods deemed sufficient for equilibrium to be attained, followed by quenching in water. The heat-treated samples were ground to powder for X-ray analysis. The lattice constants of the germanium-rich phase (a) were determined with a baok-reflection focusing camera. The X-ray reflections (331 and 422 Cr Ka, 422 and 333 Cr KB) were corrected

Jan 1, 1956

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) No. 544.-Mining engineer, 39 years of age, graduate E. M. with extensive experience in the United States, Canada and Spanish-speaking countries. Good organizer, energetic and resourceful. Experience covers mining and milling of gold, silver, lead, copper, zinc and tungsten. At present a Captain of Engineers, U. S. A., expecting to be released shortly. Open for engagement as manager, superintendent or examining engineer. Correspondence and personal interview solicited. No. 545.-Engineer and geologist, member, age 29 years, technical graduate and married. Six years' practical experience as surveyor, chief engineer and in exploration work in West, Southwest and Mexico. Speaks French and Spanish. Desires position with exploration company or as engineer and superintendent of small mine. Will be released from commission in United States Navy about February 1. No. 546.-For staff position-or manager. Member, married, graduate mining and metallurgical engineer, 18 years' experience in underground and metallurgical work on gold, silver, copper, lead and zinc ores. Details, references, and qualifications will be sent if requested, or may be seen at Institute office. Available immediately in United States or Canada. Would go reasonable distance for an interview if desired. No. 547.-Member, experienced in mine operating, engineering, general contracting and constructing. Technical graduate, mining engineer, married, age 38 years. Many years' practical experience while advancing through different positions to manager. Best of references and rating. Desires change. Position with future. Can obtain results. Salary commensurate with position. Available on short notice. No. 548.-Mining engineer, member, technical graduate, age 31, on military service since August, 1914, available after January 31. Best of references.

Jan 3, 1919

By W. H. Meyer

During the seventeen years Fairchild has been making aerial surveys and aerial photographic equipment many changes and improvements have been made in the equipment and in the technique of using it. Aerial photographic operations have been developed from the crude methods and apparatus of wartime to a science upon which exact engineering calculations can be based. In the early days there was no airplane specially designed to meet aerial photographic requirements. One type of camera was used in all types of operations. Projects were made to conform to the products we could make and deliver. Obviously this entailed definite limitations. We now have airplanes designed specially for aerial photographic operations in accordance with the conditions encountered in actual service experience. We have cameras for every photographic purpose and our laboratory technique and equipment have been developed to the point where it is possible to make contour maps from vertical aerial photographs with contour intervals as close as five feet. Therefore, the selection of equipment now can be made in accordance with the time at our disposal, the justifiable cost, the scale desired, and the general requirements of the client. This does not mean, however, that arbitrary deliveries can be set for aerial photographic products. The factors in each project vary and each job must be considered in accordance with the factors involved. This accounts for the fact that products of aerial surveys may readily vary from $1.25 to $200 a square mile. Sherman M. Fairchild became interested in the design of a radically different aerial camera during the war. At its close he was about ready to demonstrate his design to the War Department. By 1920, he was able to bring out his first completed model. It had a number of radical features, one of which was the first dependable high-speed between-the-lens shutter, which makes for accuracy in aerial photographic work. Another feature was the use of metal throughout, eliminating the wooden parts that had been employed in wartime cameras. Another feature was the interchangeability of parts.

Jan 1, 1937

By J. McLaren Forbes

Geologists and engineers in charge of diamond drilling often have no practical experience in the work, yet they must direct the drillers. In discussing some of the problems that arise, the author of this paper has tried to remember the things he did not know about diamond drilling when he first came in contact with that work. The basic reason for most diamond-drill holes is to obtain information. The more thorough the understanding of the geological and engineering problems involved, the greater will be the benefit derived from a drilling program. One of the best methods to ensure some thinking before drilling is to record on the permanent drill log, before the hole is collared, the reasons for the work and the information desired from that particular hole. When the hole is finished, the information obtained should be recorded. Driller The choice of a diamond driller is very important. If no experienced driller is available, a competent miner who has a sense of responsibility and better than average mechanical ingenuity can do the work. The best answer to most practical drilling problems, from the standpoint of the person in charge of the drilling program, is the service of experienced diamond drillers or drilling firms. Equipment Drilling equipment should be adequate to put down the longest hole desired and handle the toughest ground encountered. The type of bit used depends upon the ground drilled. Experimenting with various bits and careful study of footage records are the best means of determining which to use. Under ordinary circumstances it is best to drill using an EX barrel when possible. The length of rod and core barrels that can be used depends on the size of the drill station. Also, the length of core barrel depends on the way the ground cores. In good ground as much core will be recovered with a 10-ft. barrel as with a shorter one, and with considerable saving of drilling time. A water pump is needed if the hole is so deep that the water pressure is not strong enough to wash out the cuttings, or if it is drilled at an angle that prevents full force of the water pressure. Instructions For an Inexperienced Driller 1. Never run a bit too long a time. When a bit seems to be "good for one more run," discard it. 2. Always let the rods down on bottom easily. Protect the bit from sudden shock. 3. Start the drilling slowly and easily. Do not put pressure on the bit too fast. Diamonds can break. 4. Be sure the water pressure is strong enough to clear the bit, but do not use more water than is needed, as it may wash away the core. Usually, if no core is recovered the hole is a total loss. 5. When dry-blocking, do not run without water longer than necessary as the bit may burn. 6. Be sure the rods are well caulked and tightly screwed together. If not well caulked they will lose water, and if not

Jan 1, 1946

By E. W. Parker

THE anthracite region, from which there is produced annually about 80,000,000 tons, or approximately 15 per cent. of the total coal supply of the United States, has a combined area of a little less than 500 sq. mi. The total area occupied by the bituminous fields (including the sub-bituminous and lignite fields) is in the neighborhood of 400,000 sq. mi., so that 15 per cent. of the total output comes from this small area of only a little more than 0.1 per cent. of the coal-producing territory. of the United States. The productive anthracite area is divided into a series of basins or troughs, roughly parallel, extending. in a northeast-southwest direction through the. Counties

Jan 1, 1921

By S. J. Matas, R. F. Hehemann, R. H. Goodenow

The hot-stage metallographic method has been employed to determine radial growth rates of upper and lower bainite. Lower bainite appears to grow as individual plates that increase in both length and thickness while upper bainite grows as sheaves of closely spaced plates or needles. A discontinuity in the temperature dependence of the growth rate appears to be associated with the transition from upper to lower bainite and stepped quenching experiments suggest that lower bainite will not continue to grow when the temperature is raised to the upper range. Thus, a single process does not appear to control the growth of both upper and lower bainite. A tentative model based on the forces acting on a dislocation interface is proposed to account for the slow growth of bainite. It has been recognized since the early studies of Davenport and Bain that a close relationship exists between the martensite and bainite transformations in steels. However, diffusion of carbon during the transformation has lead to considerable controversy concerning the reaction mechanism.1-7 Many studies4,5,7-9 have emphasized the structura and kinetic aspects of the bainite reaction and, in particular, the difference observed between the two forms of bainite—frequently termed upper and lower bainite. A kinetic difference between the two types of bainite has been revealed in the activation energy determined from the overall reaction;4,5 however, many difficulties arise in an interpretation of these activation energies since a number of temperature dependent factors contribute to the kinetics of the overall reaction. The displacive surface relief10 accompanying the bainite reaction permits a separation of the nuclea-tion and growth contributions to the reaction and allows the kinetics of the growth process to be examined. Several investigations of this type have been conducted; however, they have been restricted to the low temperature range.3'6'11 Here, bainite plates are observed to grow slowly in both length and width. The present investigation extends such studies to include the upper bainite range. MATERIALS AND PROCEDURE Materials. The composition of the steels studied in this investigation are presented in Table I. The range of composition permitted a study of the effect of carbon content on the growth rate of upper bainite in the 9 pct Ni steels and consideration of both upper and lower bainite in the higher carbon steels. These steels were received as hot-rolled rounds and were forged to approximately 1/2 in. thick plates for preparation of metallographic specimens. In order to produce an essentially zero carbon steel, Steel A was decarburized in wet hydrogen at 1550°F for 15 days with the result tabulated as Steel AD. Experimental Procedure. In order to study the slow growth of the displacive transformation product, a commercially available Leitz hot stage was modified to permit heating of the specimen by its own resistance in a manner similar to that employed by other investigators.6 The furnace chamber was maintained at a pressure of 2 to 3 X 10-5 mm Hg prior to austenitizing at 2000° ± 12° F for 5 min. Samples could be cooled from the austenitizing to the transformation temperature in approximately 15 sec and the progress of transformation was recorded with a 9 cm by 12 cm single frame camera or a 16 mm movie camera. RESULTS AND DISCUSSION Growth Characteristics. The general growth characteristics observed in this investigation were analogous to those reported previously.3,6,11 Typical growth sequences for the high temperature and low temperature forms are illustrated in Figs. 1 to 5. In both temperature ranges, bainite plates increase in length at slow, temperature dependent rates until interrupted by a grain boundary, another plate, or

Jan 1, 1963

By H. N. Eavenson

Prior to 1907 nearly all coke was made in beehive ovens, and most of the gas produced was made in the old-style gas retorts, and while there were a few coke plants in southern West Virginia, southwest Virginia and Kentucky operating on high-volatile coals the proportion of the total product made by them was small and usually was used locally. The greater part of the coke made, and the coal gas produced, came from the Pittsburgh seam of western Pennsylvania and northern West Virginia, which was then regarded as the standard coking and gas coal of the country, and the best coal available anywhere for these purposes. With the advent of the byproduct oven and the building of coke plants at the furnaces, the restriction of the use of one grade of coal for making coke was removed and the use of mixtures of low-volatile and high-volatile coals began. The change in the locations of the coke plants removed the necessity of using Connellsville coal and also made sources of gas available to the public utilities other than of their own manufacture. Most of the first oven plants were built at points distant from the Connellsville region and this afforded an opportunity for the use of coals from the southern Appalachian fields, which were then at approximately equal distances from the ovens. Since that time development has been made on a number of seams of coal of great purity in southern West Virginia, southwestern Virginia and eastern Kentucky, which have been largely used for gas, cokemaking and metallurgical purposes where low amounts of ash, sulfur and phosphorus are determining factors. These coals are much lower in the objectionable elements than most of the coal shipped from the Pittsburgh seam, or than any northern coal, and when blended with low-volntile cod produce coke in byproduct ovens that is not excelled for any purpose by any coal mined in this country, and is equaled very seldom. Coal from several of these scams is shipped in great quantities without beneficlation and is lower in ash and sulfur than any but the best washed product from the Pittsburgh seam in the north. The writer has made a study of these coals to ascertain their relative qualities and the areas and reserves of coal available in each of them. No attention has been paid to the coals of Alabama, which do not compete with any of these coals, and no coal of equivalent quality is found in

Jan 1, 1934