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By J. E. Burke, C. W. Mason

In attempting to study precipitation from a tetragonal lattice, using solid solutione of bismuth in tin, it was found that although a Widmanstätten pattern is observed1,4 only a qualitative analysis of the orientation relationships is possible, because of the unusual structural changes that accompany the precipitation process. Microscopical Studies Alloys were made from Chempur tin (Standard samples 42b and 426, National Bureau of Standards), and bismuth (Kahl-baum C.P.) by melting weighed quantities together under palm oil, stirring well, and castilig in a heated graphite mold. The polishing and etching techniques employed largely govern the visibility of the structural changes. The preliminary surfacing operations were similar to those recommended by Villela and Bergekoff,5 through Behr-Manning 3/0 abrasive papers, lubricated by a solution of paraffin in kerosene. A rough metallographic polish was next given, using a thin cotton cloth charged with relevigated alumina (maximum particle size of about 4µ) and soap solution; repeated etching and polishing served to remove disturbed metal. For high-power examination better preparation was necessary. It was found that on such soft metals the threads of the fabric, rather than the abrasive, cause most of the scratching. Cotton outing flannel, which had been brushed so that the nap lay down, was fairly satisfactory, but a heavy grade of silk velvet (not the noncrushable kind) was found to be better, especially after some use. A better procedure was as follows: The metal lap was warmed slightly, and a 4-in. circle of woolen broadcloth was cemented to its center by a thin film of melted paraffin. The broadcloth was then moistened with water, and a 30 to 40 per cent solution of sodium hydroxide heated to about 50°C. was poured over it, allowed to stand for I to 2 min. and then washed off. It was neither necessary nor desirable to remove all the sodium hydroxide from the cloth, since its etching action aided in the removal of the flowed layer from the sample. The cloth was then charged with a paste of the relevigated alumina in water. Since this lap did not remove deep scratches, it was necessary previously to polish the specimen on some material such as the silk velvet. The sodium hydroxide softens and partly gelatinizes the woolen lap covering, permitting a scratch-free polish, but its action continues, and the cloth deterioratcs after about 24 hr. This is not serious, because a new lap can be prepared in about 5 min., and only small pieces of cloth are used. Etching with a strongly acid solution of ferric chloride was found satisfactory for removing the flowed layer. For the final etching, the most satisfactory reagent was that of Tafls,7 the formula for which is: FeC13.6H2O, 2 grams; HC1, 5 c.c.; H2O, 30 c.c.; C2H5OH (95 per cent), 60 C.C. This etchant reveals differences in com-

Jan 1, 1942

By J. E. Burke, C. W. Mason

In attempting to study precipitation from a tetragonal lattice, using solid solutione of bismuth in tin, it was found that although a Widmanstätten pattern is observed1,4 only a qualitative analysis of the orientation relationships is possible, because of the unusual structural changes that accompany the precipitation process. Microscopical Studies Alloys were made from Chempur tin (Standard samples 42b and 426, National Bureau of Standards), and bismuth (Kahl-baum C.P.) by melting weighed quantities together under palm oil, stirring well, and castilig in a heated graphite mold. The polishing and etching techniques employed largely govern the visibility of the structural changes. The preliminary surfacing operations were similar to those recommended by Villela and Bergekoff,5 through Behr-Manning 3/0 abrasive papers, lubricated by a solution of paraffin in kerosene. A rough metallographic polish was next given, using a thin cotton cloth charged with relevigated alumina (maximum particle size of about 4µ) and soap solution; repeated etching and polishing served to remove disturbed metal. For high-power examination better preparation was necessary. It was found that on such soft metals the threads of the fabric, rather than the abrasive, cause most of the scratching. Cotton outing flannel, which had been brushed so that the nap lay down, was fairly satisfactory, but a heavy grade of silk velvet (not the noncrushable kind) was found to be better, especially after some use. A better procedure was as follows: The metal lap was warmed slightly, and a 4-in. circle of woolen broadcloth was cemented to its center by a thin film of melted paraffin. The broadcloth was then moistened with water, and a 30 to 40 per cent solution of sodium hydroxide heated to about 50°C. was poured over it, allowed to stand for I to 2 min. and then washed off. It was neither necessary nor desirable to remove all the sodium hydroxide from the cloth, since its etching action aided in the removal of the flowed layer from the sample. The cloth was then charged with a paste of the relevigated alumina in water. Since this lap did not remove deep scratches, it was necessary previously to polish the specimen on some material such as the silk velvet. The sodium hydroxide softens and partly gelatinizes the woolen lap covering, permitting a scratch-free polish, but its action continues, and the cloth deterioratcs after about 24 hr. This is not serious, because a new lap can be prepared in about 5 min., and only small pieces of cloth are used. Etching with a strongly acid solution of ferric chloride was found satisfactory for removing the flowed layer. For the final etching, the most satisfactory reagent was that of Tafls,7 the formula for which is: FeC13.6H2O, 2 grams; HC1, 5 c.c.; H2O, 30 c.c.; C2H5OH (95 per cent), 60 C.C. This etchant reveals differences in com-

Jan 1, 1942

By Walter A. English

CONTENTS PAGE Introduction. By WALTER A. ENGLISH 1 Theory of Seismic Reflection Prospecting. By WILLARD H. TRACY 2 Instruments for Reflection Seismograph Prospecting. By ARTHUR NOMANN 9 Seismograph Field Operations. By FRANK ITTNER 15 Determining Geologic Structure from Seismograph Records. By P. C. KELLY 22 INTRODUCTION BY WALTER A. ENGLISH,* MEMBER A.I.M.E. THE four papers making up this symposum have been prepared espe-cially for those who have no knowledge of seismograph prospecting. To many people mathematics is a formidable subject, and many are discouraged from studying seismograph prospecting under the mistaken assumption that the mathematical requirements are severe. In the papers presented here there is not a single mathematical equation. We believe that considerable competence in dealing with some of the most important problems of this work can be attained without any mathe-matical training whatever. At the present time, there is a real need for interpretation of results by persons thoroughly competent to bring geologic experience and imagination to bear on data that are subject to multiple interpretation from a strictly physical viewpoint. Likewise, those charged with the responsibility of planning seismo-graph exploration campaigns would do well to become familiar with as . much as possible of the technical aspects of the work. They would then be in better position to judge of its success in individual cases. It has often been said that the seismograph is a new structure-finding tool for the geologists to use. Using a tool and using its product are two different things. One does not use an automatic screw-threading machine when he buys a box of screws at the hardware store. Neither does the geologist

Jan 1, 1939

Readers of recent Bulletins have doubtless observed that the problem of improving both material and moral condition of employees is receiving close attention from influential members of the Institute. This will lend interest to certain developments and investigations that have been reported elsewhere.

Jan 5, 1918

By Frank G. Snyder, Paul E. Gerdemann

The Southeast Missouri lead district, located about 70 miles south of St. Louis, embraces four important sub-districts and several minor ones. The important sub-districts, in order of discovery, are Mine La Motte, the Old Lead Belt, Indian Creek, and the Viburnum Lead Belt. Descriptions that follow are of geology and ore deposits of the Old Lead Belt. The ore deposits are stratiform in character and are localized in a narrow carbonate bar and algal reef environment on the flanks of exposed Precambrian of the St. Francois Mountains. Ore structures include a variety of primary depositional features such as pinchout zones, disconformities, ridge structures, reefs, and submarine gravity slides. Faulting, prior to and during ore deposition, "prepared" the host rock and strongly fractured areas are mineralized much more intensively and extensively than unfractured parts of the same sedimentary structures. The deposits are epigenetic in character. Mineralization is believed to have occurred at the time that post-lower Ordovician faulting took place. The mineralizing solutions are believed to be concentrated brines from adjacent basins that moved out of the basins during faulting, uplift, and erosion of the St. Francois positive area.

Jan 1, 1968

By Oliver Bowles

STRIKING new developments in the field of industrial minerals include the employment of lime, salt, coal, and air for the manufacture of stockings, and the substitution of paper for granite and marble in making tombstones. Certain minerals that have heretofore been regarded as valueless except as museum or laboratory specimens, are now being applied commercially. Serpentine, in forms neither fibrous nor ornamental, massive topaz, pinite, and zoisite are examples. For certain other minerals, notably pyrophyllite, bentonite, vermiculite, and sulphur, extension of established uses into new fields has occurred. Substitution takes a toll in many industries, but producers of industrial minerals as a class have gained more than they have lost in recent years. Encouraging progress has been made in developing at long last a suitable substitute for certain of the uses of mica, the only industrial mineral on the strategic list of commodities established by the War. and Navy Munitions Board. Some of the more important developments in process, equipment, and use .that have come

Jan 1, 1940

By R. J. Wasilewski

Elastic constants have been determined on single crystals of maximum-melting-temperature NiAl compound (50.6 at. pct Al) at 25°C. Temperature variations of Young&apos;s modulus in the three principal crystal directions between -150°C and +800°C exhibit no anomalies similar to those repovted for the isomor-phous compounds brass and AuCd. It is concluded that the ordered CsCl structure is stable throughout the temperuture range investigated NICKEL aluminide is a congruently melting inter-metallic compound of CsCl (B2) structure, stable over a rather wide composition range (40 to 54 pct Al). It exhibits a lattice-parameter maximum of a. = 2.883A at 50.6 pct 1,&apos; at which composition the excess aluminum atoms are randomly distributed on the vacant nickel sites;&apos; at higher nickel compositions the excess nickel atoms replace substitutionally in aluminum sites, while at higher aluminum compositions vacancies are present in the nickel sublattice.&apos; For compositions close to NiAl no significant variation in order has been observed at temperatures up to 900°C.3 At high nickel (65 pct) compositions the existence of a martensitic structural transformation has been reported.4 NiAl is isomorphous with the ordered B-brass structure and with the high-temperature structures of AuCd and TiNi alloys close to equiatomic composition. All of these exhibit anomalous elastic behavior as the temperature of their diffusionless transformation to lower-symmetry structures is approached.&apos;-&apos; This behavior has been explained as indicative of low stability of the CsCl structure in these compounds.8 The present paper reports the experimental determination of the elastic compliances of single-crystal NiA1. EXPERIMENTAL METHOD 1) Specimens. Polycrystalline NiAl was prepared by induction melting of carbonyl nickel and high-purity aluminum and casting into solid copper molds in gettered helium atmosphere. The castings thus produced were canned in mild steel and impact-extruded at 1100 to 1200°C to 38-in.diam rod. After the steel sheath was pickled off, the rods were converted to single crystals by repeated high-frequency satisfactorily produced the desired orientations in the form of crystals 38 in. diam by 8-12 in. long. These were subsequently center less-ground to 7 to 8 mm diam by 12 cm long, electropolished (in 80 pct methanol, 20 pct HzSO, at 25°C and 15 v), and their axial orientation determined to 1 deg by the Laue back-reflection technique. The rod dimensions were determined to 0.01 mm and the densities determined from geometrical dimensions and the weight of every specimen. The average density was 5.905 0.005 g per cu cm. 2) Elastic Data Measurements. Room-temperature elastic compliances Sii were obtained by determining to 0.1 cps the fundameGtal resonance frequencies in the longitudinal and torsional vibration modes. At these frequencies the following relations hold: E =p(2lfif =pvl= Sn- 2r[Sll- S12- -£„«] g -P(2iftf = pvf = (s<« - fr(sii - sw - ±s»y where vl and vt are the velocities, and f andft the resonance frequencies of the longitudinal and torsional waves, respectively; 1 is the length of the specimen, and r is the direction cosine factor—{cos2 a • cos2 0 + cos2 a . cos2 y + cos2 0 ¦ cos2 Y}. Given three crystals of orientations (loo), (110), and (111)) i.e., F = 0, 14, and 13, we can obtain six equations for the three unknown compliances, thus providing adequate internal check. Mode mixing can readily occur in the relatively long wavelength resonance utilized here. This could cause a significant error in the torsion wave velocities calculated from the apparent resonance frequenies. Therefore, throughout the present work, a method, described previosl,&apos; was used to ensure that no significant mode mixing took place at resonance. The apparatus used was originally designed for the Elastomat, Magnaflux Corp.. Chicago, 111. determination of flexural vibration resonance frequencies. At room temperature torsional vibration mode could be established by suitable positioning of the thin wires from the input and pick-up transducers, and longitudinal mode by cementing thin magnetic foils at the ends of the specimen, and inducing the vibration by means of electromagnetic transducers. Only flex-ural resonance frequencies could, however, be obtained reproducibly over the temperature range of -150 to 800°C. These data are considerably less accurate, the error in the modulus being estimated at -0.6 pct from the specimen dimensions and the room-temperature Poisson&apos;s ratio. The reproducibility of the resonance frequencies in repeat runs was, however, to better than l in 15,000, hence the relative elastic modulus error less than 0.02 pct. Therefore, the temperature variation of the principal Young&apos;s moduli obtained by flexural resonance, relative to room-temperature values, is believed to be satisfactorily accurate.

Jan 1, 1967

By W. G. Frailing, W. P. Sims

The Lakeview Pool of Kern County, California, was discovered in 1910 with the drilling of Lakeview No. 1 which blew out and produced an estimated 8,250,000 bbl of oil in 544 days of uncontrolled flow. The well has since been known as the Lakeview Gusher. Full exploitation of the pool did not take place until about 25 years later. A total of 112 producing wells were completed in the Lakeview sand through April 30, 1949. As of that date, about 30 per cent of the total wells drilled were still producing, with an average pool production rate of approximately 2000 bbl per day. The cumulative oil production was about 41 million bbl of oil, or 55.3 per cent of the tank oil originally in place. The pool is bordered on its down-structure side by a body of inactive edgewater and water production where present has been principally the result of coning. Since the depletion of the greater portion of the gas energy by the Lake-view Gusher, the pool has operated under gravity drive. Relatively high angle dips, good permeabilities and favorable fluid characteristics have made gravity drainage particularly effective. Since January, 1942, the oil recovery -has been relatively constant at about 53,000 bbl per ft drop in fluid level. Correlations between the volume of reservoir space drained and the cumulative oil produced indicate that an ultimate recovery of 63.3 per cent of the tank oil originally in place is attainable. INTRODUCTION The Lakeview Pool is an outstanding example of gravity drainage. It is one of many productive reservoirs of the Midway-Sunset Field, and is located in Kern County, approximately five miles southeast of Taft and two miles north of Maricopa, California. Its position rel- ative to surrounding pools and to the Thirty-Five anticline is shown on Fig. 1. The northern portion of the pool lies in sections 32 and 33, Township 32 South, Range 24 East, Mt. Diablo Base and Meridian, while the southern portion lies in sections 25, 26, 35 and 36, Township 12 North, Range 24 West, San Bernardino Base and Meridian. As no two sections bear the same number, they will hereafter be referred to by section number alone. The purpose of this paper is to review the performance of the Lakeview Pool in an effort to evaluate the effectiveness of gravity drive as a recovery mechanism. REGIONAL STRATIGRAPHY AND STRUCTURE The oustanding structural feature is this area is the Thirty-Five anticline, the axis of which plunges South 75" East through the center of Section 35. As shown on Fig. 2, the following zones are oil and gas bearing in the Thirty-Five anticline area: Pleistocene Basal Tulare Tar Sands Pliocene San Joaquin Mya Sands Top Oil or Scalez Zone Etchegoin Kinsey Sand Wilhelm Zone Gusher Sand Calitroleum Sand Miocene Reef Ridge Lakeview Sand Sub-Lakeview Miocene Sands Monarch Sands or fractured shale equivalent Maricopa Webster Sand or fractured shale equivalent Fractured Shale-Uvigerina Zone C Obispo Sand and fractured shale equivalent Pacific Shale Zone The productive interval of the Lakeview Pool is limited to Upper Miocene and Lower Pliocene deposition. In this general area, the most prevalent type of accumulation results from stratigraphic traps or permeability pinchouts. As is the case of the Lakeview Pool, strati-graphic traps resulting from angular unconformities are present. The structure within the Miocene does not parallel that of the Etchegoin (Pliocene), as the Miocene beds were folded, and in places faulted, and subjected to erosion prior to Pliocene deposition. The Lakeview horizon consists of truncated sands which occur on the northeast flank of the Thirty-Five anticline. The direction of strike is west and northwesterly through sections 25 and 36 and continues northwesterly through sections 26 and 33, to the approximate center of section 32. At this point the strike swings to the northeast and the horizon re-enters section 33. in the northwest corner. The change in strike in section 32 affords synclinal accumulation at that point. The Lake-view sand is truncated updip by the Etchegoin overlap. To the southeast, the sand shales out, while to the northwest, the productive interval appears to be limited by a combination of stratigraphic pinchout and permeability barrier. Structurally, the Lakeview reservoir presents three areas of interest, as shown on Fig. 3. Area I in section 32 is a region in which a productive Sub-Lakeview Miocene sand is present. It occurs from 10 feet to 30 feet below the base of the Lakeview sand and attains a maximum thickness of 25 feet in Well No. 21, section 32. The producing characteristics of the Sub-Lakeview Miocene sand differ radically from those of the Lakeview sand. Water production at high structural locations and abnormally high fluid levels indicate that there was no communication with the Lakeview sand. Wells in Area I penetrated this sand and produced it in conjunction with the Lakeview sand. In Area 11, the Lakeview sand is a

Jan 1, 1950

By Oliver Bowles

DELICATE PLANTS are now put to bed for the winter under glass-wool or rock-wool blankets. Thus arise new and unexpected uses for non-metallic materials and rocks and, at the same time, certain unique uses are fading out; for instance, the Italians have taken steps to bar the use of salt for money in Ethiopia. Novel sources of supply find a place in the record of recent achievements as exemplified in the migration of the frontiers of industrial mineral exploitation beyond the land area of the earth to include the ocean. Salt, of course, has been recovered from the sea for years but the treatment of enormous quantities of sea water for bromine has lately added to the importance of the ocean as a reservoir of mineral wealth. Increased use of non-metallic minerals in the commercial and economic life of the country is reflected in the wide scope and activity of the Industrial Minerals Division of the Institute. The outstanding recent achievement of the Division is the publication of a 955-page volume on industrial minerals and rocks, comprising 48 commodity chapters each written by an authority on the subject.

Jan 1, 1938

By Ralph W. Marsden

The natural iron ores of the Lake Superior Region in the United States are being replaced by iron-ore concentrates produced from magnetite- or hematite-rich horizons in the Precambrian cherty iron formations. The production of natural ores will soon be less than one-half of the total ore shipped annually. The tonnage of natural ore produced will continue to decline until it is a minor percentage of the ore shipped. The natural ores include (1) soft ore, (2) hard ore, ( 3) conglomerate ore and ( 4) siliceous ore. The soft ores are the important ore type and are sometimes termed "Lake Superior type ore". These ores are in situ deposits of hematite and limonite formed by the leaching of silica and other gangue materials in the iron formations. The leaching is believed to have been done by downward moving surface waters. In deep ore deposits, generally over 1000 feet below the present surface, circulation and leaching action may have been assisted by hydrothermal activity. Hard ore deposits occur on the Vermilion and Marquette ranges where hematite or magnetite has replaced the silica (and possibly some silicates) in cherty iron formation. These ores commonly occur in structural situations favorable for the movement of hydrothermal waters. The ores are believed to be the result of hydrothermal action with iron, possibly from the iron formation, transported by hydrothermal waters to areas favorable for the replacement of silica by iron oxides. Certain stratigraphic horizons of the Lake Superior Precambrian cherty iron formations contain sufficient iron as magnetite or hematite, with a grain size and texture that will give adequate mineral liberation, to yield an ore-quality product after grinding and concentration. The magnetite-rich deposits are termed magnetite taconites. These ores occur on the Mesabi, Gogebic, and Marquette ranges. Magnetite taconite ores are unenriched cherty iron formation and are the result of the sedimentary deposition of the iron formation and the metamorphic history of the rock. The commercial quality hematite-rich iron formations in Michigan are termed jasper ores. The jasper ores are being mined on the Marquette and Menominee ranges. These ores are composed of specular or granular hematite associated with quartz and iron silicates. The jasper ores appear to be recrystallized iron formations in which iron, prior to recrystallization, occurred as hematite.

Jan 1, 1968

By E. C. Wright

FOR many years the cost of making pig iron and steel in the Birmingham district has been about the lowest in the United States. The close proximity of the important raw materials such as coal, iron ore, limestone, and the large available scrap supply made it possible to assemble all of the important ingredients necessary for steel- making with only nominal costs for transportation. Both iron ore and coal were being mined in this district at one time for about $1 per ton from underground operations. At that time mining wages were low everywhere and the labor rate in the South was considerably below that of other mining districts. This situation persisted until the emergence of labor unions as an economic and political force, emigation of southern labor to northern plants, and continued growth of industry in the South in the years following the depression of 1932. Since that time union organizing of miners and steel workers throughout the nation has increased labor costs in mining and steelmaking. This influence has been felt particularly in underground mining operations since the proportion of labor cost to total cost is still high. The previous advantage in basic labor rate in the South has been almost entirely eliminated by the equalization of labor rates in basic industries by national unions. Since 1945 these influences have been especially noticeable in increasing the cost of mining coal and iron ore in the South. The northern steel districts are still being largely supplied with iron ore from the Minnesota open-pit mines and the cost of this ore has not increased nearly as much as the cost of ore obtained from underground mines in Birmingham. A similar situation exists in coal mining; the thinner seams in Alabama are not so amenable to mechanization as the northern mines and, as a result, the output per man-day in southern mines is only about three tons of coal as compared to five or six tons per man-day in the large captive mines of West Vir-

Jan 1, 1950

By Charles Janin

(San Francisco Meeting, October, 1911.) THE first successful bucket-elevator dredge to operate in California was put in commission at Oroville in March, 1898. There had been numerous previous attempts at dredging, but none of the earlier boats proved a success. The gold-miners in California early conceived the idea of a machine to dig gravel from the beds and bars of auriferous streams that were inaccessible by the methods then employed, and it was only a few months after the discovery of gold in California that such a machine was. shipped around Cape Horn from New York to San Francisco. This was, however, but the forerunner of many failures in gold-dredging, and was soon at the bottom of the Sacramento river. During succeeding years many other unsuccessful attempts were made, and it was not until 1897 that a dredge of the single-lift bucket-elevator type was floated on the Yuba river. This dredge was built by the Risdon Iron Works for R. H. Postlethwaite, and would probably have been a success if it had been operated on some of the rich Oroville ground instead of in a turbulent stream, where the dredge was wrecked during a flood, and was not repaired. Fig. 1 is a sketch-map of California, showing gold-dredging areas. It is not my intention to narrate in detail the history of the early failures in gold-dredging, and the various steps in the development of the modern boat, but merely to touch upon this in a general way, and to call attention to the wide difference in capacity and operating-cost between the first successful dredge, with an actual capacity of 600 cu. yd. per day-though its rated capacity was in excess of this-and the present modern dredge with 15-cu. ft. buckets, and an average capacity of 250,000 cu. .yd. per month. Even this enormous capacity has several times been exceeded on monthly runs. The first successful dredges

Mar 1, 1912

By Samuel S. Wyer

THE installation of the gas-producer power-plant in America has been so unusual that all engineers have viewed it with in¬terest; a large majority, however, regard it with a lack of con-fidence and many with positive distrust. Despite the fact that European engineers have usually been less inclined to take the initiative along experimental lines than are Americans, they have, nevertheless, developed the gas-producer plant to a very high state of efficiency to which they were forced by the neces¬sity of economy in fuel-consumption. The gas-producer power-plant is so common in Europe that engineers as well as the general public regard it with the same degree of confidence that is now universally placed in steam¬plants. Gas-engines, both small and large, are in general use there, and central stations, aggregating several thousand horse¬power, are quite numerous. The fact that gas-producer power-plants have received so little attention in America may be attributed to five conditions:-1&apos;, ignorance and prejudice; 2, newness of work; 3, in-

Mar 1, 1905

By Richard J. Robbins

Mechanical moles have developed through a tedious process of evolution. At times it has seemed that tunnel borers have been subject to the same Darwinian rules of evolution as their zoological namesakes who, despite their efficiency, are highly specialized and still restricted to soft soil conditions near the surface of the ground. HISTORICAL HIGHLIGHTS The Robbins Co. began its work in this field in 1947 with the development of a twin-bore continuous coal miner. Although these machines were used primarily in coal, two of the early prototypes were used to bore tunnels through shale. Disk cutters were first used on these machines and showed promising results as core breakers between drag-bit kerfs. In 1953, James S. Robbins and Assocs. undertook the development of a 25-ft 9-in.-diam circular tunnel borer for Mittry Construction Co. to be used at Oahe Dam in South Dakota (Fig. 1). This is believed to be the first rock tunnel-boring machine built since the end of the 19th century when short sections of the Channel tunnel were successfully bored in chalk from both the English and French shores. Another Oahe Dam machine was built in 1955, and then a series of three small-diameter machines for the company&apos;s first real experience with medium-hard and hard rock (Fig. 2) None of these three could be considered a success, although they laid the groundwork for the success that followed. Interbedded shale and limestone in Pittsburgh and hard limestone in Chicago quickly pointed up the weaknesses in these machines which were used by Perini, Dravo, and Healey. Among the problems were the high breakage rate of tungsten-carbide drag bits, too much flexibility in the drive shafts, failure of high-pressure hydraulic systems, chain-conveyor failure, and general lack of rigidity and strength. In 1956 another attempt at medium-hard and hard rock-boring proved this time to be a success and a significant turning point in the development

Jan 1, 1970

By C. M. Young

The safety lamp is the most common and convenient apparatus for detecting inflammable gases in mines, the presence of gas being shown by a blue flame, called the cap, if the wick has been lowered to suppress the luminous flame. The height of the cap increases with the proportion of gas and with the temperature of the lamp flame. Lamps of the Wolf type, the fuel of which is benzine, have a hotter flame than lamps in which vegetable oils are used, such as the Davy, and the Clanny, and are more sensitive than the latter and their many modifications. The Piehler alcohol lamp gives a still higher cap while the Clowes hydrogen lamp is most sensitive of all. While the effect of the temperature of the source of ignition is well known, the writer knows of no previous attempt to correlate the change of this temperature with change of the height of the cap produced, In order to determine the height of the cap at various temperatures, it was necessary to have a source of ignition the temperature of which could be accurately controlled over a considerable range. This condition was met by a coil of wire of high fusing point heated by an electric current controlled by a variable resistance. The use of a coil offered the further advantage of freedom from complications due to the flame of a burning fuel. Such a flame, being itself of variable height, would to some extent raise or lower the elevation of the base of the cap and therefore add to the difficulty of determining the height of the cap. Besides this, the presence of a small cap from the lamp fuel, commonly known as the "fuel cap," would interfere with the observation of small gas caps. After some experiment, a coil was made of platinum wire, No. 26, diameter 0.016 in. The coil was 17/64 in. (6.746 mm.) in outside diameter and had eight full turns in a length of 1/2 in. (12.69 mm.). This was connected to an electric circuit through an adjustable resistance, as shown in Fig. 1. In order to measure the temperature, a thermocouple was inserted in the center of the coil; the leads passed out at the ends and were ccnducted to a millivoltmeter. It is probable that the current of air passing upward through the coil resulted in the indication of a tempera-

Jan 1, 1920

By Lucien Eaton

VENTILATION in the iron mines of the Lake Superior region in nearly all cases is natural; that is, it is induced by the difference in elevation between different outlets in the mine and by the difference in temperature of the air in the mine and that outside. This difference in temperature is frequently augmented by placing a steampipe in the upcast shaft; but aside from this, artificial aids to ventilation have been rare until - recent years. In some of the older mines, as at the Cliffs Shaft mine at Ishpeming, Mich., in the 80&apos;s, fans have been used when there was only one opening to surface, but their use was abandoned as soon as a natural circulation of air started. In recent years, the Newport mine at Ironwood, Mich., was the first to use positive mechanical ventilation. The installation was not large enough, however, to give definite results, reliance being placed largely on natural ventilation. With the coming of warm weather in the spring of 1914, the necessity of positive mechanical ventilation at the Lake mine of the Cleveland-Cliffs Iron Co. at Ishpeming, Mich., became evident. The workings of the Lake mine are under the bed of old Lake Angeline, which was pumped out in 1894, and the mine had been in operation for 6 years prior to that date making a total of 26 years of continuous operation. The total production, up to 1914, amounted to over 8,000,000 tons. The ore was first mined by square-set rooms and pillars, but this was later changed to top slicing and caving. Both methods required the use of large amounts of timber, probably 80,000,000 board feet in all, practically all of which remained in the timber mat. The slow oxidation of this timber was one of the principal causes leading to the installation of mechanical ventilation. The mine was served by only one working shaft, called No. 4, a second outlet being provided by a raise to the surface from the old workings on the south side of the mine. This raise was the "down cast;" but it was very small and the drifts and raises leading to it were too small and crooked to permit an adequate amount of air to enter the mine, especially during the warmer weather. Measure-

Jan 8, 1920

DAVE BARTLEY and Edwin F. Gray, miners, late of Shasta County, California, young, healthy, and "dead broke," arrived at Ely, Nevada, one evening in the summer of 1900. Before rustling jobs and going to work, they decided to look around the camp, and in pursuance of this plan they visited a number of claims owned by D. C. McDonald, Justice of the Peace and pioneer of the district. Among the claims he showed them were the Ruth (named after his daughter) and the Kearsarge. Both were regarded as possible gold or silver properties. For no very definite reason the two miners changed their plan and took a lease and option to buy the two claims for $3500. After the transaction was closed and the partners were alone, Gray asked Bartley what he thought of the ground. "If she&apos;s good for anything, it&apos;s copper" was the reply; and, so far as the records disclose, that was the first time that anyone ever thought of Ely or the Robinson mining district, as it was called, as a possible copper area. There were some slight surface indications of copper, but it is probable that the fact that Bartley had just come from a copper district had something to do with his predilection for a metal that was much despised around Ely. In any event, his hunch was good, and he spoke with the wisdom of an oracle. For thirty years prospectors had sought gold and silver around the camp. Several stamp mills and cyanide plants had been put up and a hundred shafts had been sunk, but fate had been indifferent in its rewards to the optimistic owners. Copper ore would have to be hauled by wagon, 150 miles down Steptoe Valley to the Southern Pacific Railroad, and there was scant hope of finding ore that would bear this cost. W. B. Graham, who ran the general store in Ely, grubstaked Bartley and Gray, furnishing them with food and mining

Jan 1, 1933

By J. C. Fisher

Nucleation theory is applied to martensite nucleation in substitutional iron alloys. Composition fluctuations are neglected, and a steady rate of nucleation is predicted for any composition and temperature. The maximum rate of nucleation (as a function of temperature) is shown to be measurable only for on extremely narrow composition range, being too great or too small outside this range. A number of experimental observations, including completely isothermal transformation in some alloys and composition-dependence of M. temperature in others, are compared with the calculated behavior. IN a previous report,¹ nucleation theory was applied to the formation of isothermal martensite in an Fe-Ni-Mn alloy. The experimental observations of Cech and Hollomon² were accounted for quantitatively. It now is of interest to examine the predictions of nucleation theory with respect to martensite transformation in substitutional iron alloys of other compositions. Since Fe-Ni alloys have received considerable attention, both as to their transformation kinetics and their free energies, they will be treated in detail, although the results apply with equal validity to other substitutional alloys. In substitutional alloys, where composition fluctuations can be neglected in volumes of critical nuclear size, the rate of nucleation of martensite in subcooled austenite is¹ n - Nv exp (—W*/kT) [I] where the free energy of formation of the critical size nucleus is W* = 8192 p (?² s³) [2] In the expressions for n and W*, the symbols have the following meanings: N is the number of atoms per unit volume; v, the atomic vibration frequency; 8, a function of the elastic constants of austenite and the shear angle of martensite; , the austenite/mar-tensite inter facial free energy; and ?fc is the free energy change per unit volume accompanying the transformation. Jones and Pumphrey² have determined the austenite to martensite free energy change as a function of nickel content and temperature for Fe-Ni alloys. Their expression is ?F = 2500 C + 1.25 (1 —C)?FFc cal per mol [3] where C is the atom fraction of nickel, and ?Ffe is the free energy change per unit volume for pure iron as tabulated by Zener4 (or, equivalently, Fisher"). From Eqs. 1 to 3, it is possible to calculate isothermal nucleation rates as a function of temperature and composition for Fe-Ni alloys. The only unknown parameter is (?² s³). The best value of this parameter for Fe-Ni alloys, determined from M. temperatures in a manner to be described shortly, is (?² s³)= 9.92 (10)21 cgs units [4] Taking this value of (?² s³), C-curves for isothermal nucleation were calculated for Fe-Ni alloys of several compositions, and are plotted in Fig. 1. It is evident from Fig. 1 that completely isothermal nucleation of martensite in Fe-Ni alloys can be observed experimentally for only a very narrow range of compositions. Cech and Hollomon find that a nucleation rate of about 10&apos; nuclei per cc per sec is as fast as they can follow dilatometrically, and a rate of about 10-1 nucleus per cc per sec is about the slowest that can be measured conveniently. If the nucleation rate is to lie between the limits 10-1 10 the nickel content of an Fe-Ni alloy must fall in the atomic fraction range 0.299 5 C 5 0.302. Nickel contents lower than 0.299 correspond to nucleation rates too great to follow, and those higher than 0.302 to nucleation rates too slow to measure in a reasonable time.* In view of the narrow corn- position range in which successful isothermal measurements can be made, it is not surprising that only one substitutional alloy has been described&apos; that comes close to being in the proper range.

Jan 1, 1954

By T. A. Wright

THE-Institute of Metals Division opened on Tuesday afternoon with Wheeler P. Davey as chairman and G. E. Edmunds as vice-chairman. Four papers were on the program, two being of a fundamental character. A paper on "Internal Surface in Minerals and Metals," by R. S. Dean and J. Roster, was presented by the latter; C. H. Gottschalk discussed coercive forces in powders. In answer to a question by the chairman. The author stated that he had not investigated [he temperature coefficient of resistance. A paper on "Recrystallization and Grain Growth in Cold Worked Polycrystalline Metals," by L. W. Eastwood, Arthur E. Bousu, &apos;and C. T. Eddy, was presented by Mr. Eastwood. A. great many quantitative data were given, with little reference to the theory. Theoretical considerations were discussed by Dr. Gottschalk, and C. A. Edwards of the University College of Wales, contributed very interesting comment on the relationship of size and critical strain. Dr. Edwards discussed the necessity of considering strain with time and temperature.

Jan 1, 1935

By R. W. Smith

IN the manufacture of portland cement, the basic and fundamental essential is a limestone uniformly rich in calcium carbonate and carrying less than 3 per cent magnesium carbonate. In searching for such a deposit, also having in mind quantity of rock, accessibility and quarrying facilities, the Pacific Coast Cement Co. discovered and developed its present quarry at View Cove on the east coast of Dall Island, Alaska. Dall Island is about 100 miles west of Ketchikan and 650 miles north from Seattle. It is 70 miles in length and 5 to 10 miles in width. The climatic conditions are much more favorable than would be expected. The temperature ranges from zero to 70 degrees. The precipitation is considerably more than at Seattle, although there was less snow during the last season than at Seattle. The island is rugged and mountainous; the vegetation is moss and grass and a large portion is timbered with spruce, hemlock and cedar. Some of this timber has market value. The limestone quarry is about 30 miles north of the extreme southern end of the island. The company acquired 240 acres which contain limestone of remarkable uniformity, the percentage of calcium carbonate being about 95. It is estimated that there is ample recover- able rock on the holdings to supply the cement plant at its maximum capacity for well over 100 years.

Jan 1, 1929