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By Stuart M. Buck, J. H. Bramwell, Edward H. Williams

The Southwest Virginia Improvement Company began operations in the Bluestone Flat-Top coal-field, situated in Tazewell County, Virginia, in the fall of 1881. In May, 1883, the company had built 200 coke-ovens, and by March, 188-1, had 9000 feet of entries, exclusive of air-ways, in the Nelson or Rig coal-bed of this district (which here averages eleven feet in thickness), and had extracted 200,000 tons of coal, representing an area of about twenty acres. About this opening has grown the recently incorporated city of Pocahontas, and the completion of the New River branch of the Norfolk and Western Railroad to this point enabled the company to make large contracts for supplying coal and coke, so that it was deemed necessary, on account of the limited area developed, to work the mine day and night to fill orders. At 1.30 Thursday morning, March 13th, the inhabitants of Pocahontas were awakened by a violent shock, and within a few minutes all knew that the East mine had been the scene of an explosion of so general a nature that, of the 114 men at work, not one had escaped. The daily papers gave more or less distorted accounts of the number of victims, the scenes in and about, the mine, and the probable cause of the disaster. At the request of the company, the President of the American Institute of Mining Engineers appointed the undersigned a committee of three to investigate the matter, and the committee thus constituted presents the following report, accompanied by a copy of the testimony taken daring the investigation, for preservation in the archives of the Institute. Pocahontas was reached on Thursday, April 24th, and left on Friday, May 2d. During this interval the committee made repeated visits to the mine, especially to the points, of most importance, examining it carefully in every part; and summoned a number of witnesses, twenty-six of whom appeared and testified. The mine had been left in the same state as when the bodies were

Jan 1, 1885

By G. B. Gould, F. M. Gibson

IN DECEMBER, 1934, the joint Committee on Fuel Values, of the American Institute of Minim and Metallurgical Engineers and the American Society of Mechanical Engineers, submitted a preliminary report, which briefly stated its conclusion that it was not possible to devise any formula for the valuation of coal, based upon the various physical and chemical properties, that would be generally applicable. That report also listed those chemical and physical properties of coal that are generally recognized to have some effect on its use in steam plants, and those physical characteristics of steam plants which affect, in one way or another the relative importance of the properties of coal used in them. Since then, the Committee has considered and discussed in greater detail the interrelationship of the properties of coal and plant characteristics. The conclusions of the Committee are summarized below, with certain recommendations regarding engineering procedure, which will promote the collection of more easily correlated observations with respect to this subject, and thus advance more rapidly the accumulation of data capable of general application.

Jan 1, 1936

By C. C. Hawes

SILICA is the main impurity in iron ore. It is intimately associated with the iron oxide, sometimes free but more often in the combined state, as a mineral silicate. Its separation and purification sometimes present difficult problems to the analyst. In the absence of any definite knowledge to the contrary, orthosilicic acid. H4SiO4, is supposed to be the only silicic acid made, all other forms, such as metasilicic acid, H2SiO3, representing different degrees of its dehydration. These acids are exceedingly weak but form the most stable compounds found in nature. They are known as the silicate minerals and are formed by the combination of the different metallic oxides

Jan 1, 1936

By M. S. Klima, P. T. Luckie

Interfacing new or improved unit operations SUBMODULES with the EXECUTIVE of a macro analysis simulator usually requires modification of the input data. For example, particle processing SUBMODULES that are sufficiently general in nature to provide useful predictions require input data for rather narrow size fractions. Such data is not always available for the EXECUTIVE and must therefore be generated by the SUBMODULE. A successful interface to allow incorporation of a new SUBMODULE for comminution and one for classification in a general stream state flowsheet simulator is presented. The general nature of the SUBMODULES, as well as the logic of expanding and contracting the required data input is discussed.

Jan 1, 1983

James Douglas will long be remembered as a distinguished mining engineer and metallurgist, as a scientist with broad vision, as an executive whose understanding of practical problems coupled with his knowledge of men and affairs enabled him to weld together great mining interests and to their service build railroads and bring power. More, he will be recalled as a philosopher and a writer of charm, a historian of no mean order, and one whose catholic tastes and enthusiasms led him into the fields of education, medicine and theology. His aim was to possess that which he considered made life worth while—friends and effectiveness in whatever task he undertook. In this aim he was successful to a degree exceeded by few, as thousands of his friends and associates could and can testify. Dr. Douglas was born on November 4,1837, at Quebec, Canada. His father, James Douglas, Sr., was a prominent physician and the leading surgeon of Canada. He also established the first retreat for the insane in the Dominion, the Quebec Lunatic Asylum, to which he devoted his services for years; The son followed in the footsteps of his father and studied medicine, not only in Canada but also in Scotland and in Germany. He entered the University of Edinburgh in 1855 but after two years at that institution returned to Canada and was graduated from Queens university at Kingston, Ontario, .with the degree of Bachelor of Arts. Later he went to Lava1 University, Quebec, and subsequently became professor of chemistry at Morrin College, Quebec. After he was graduated—at the time he considered his formal education completed—he traveled with his father in Europe and in the Orient; visiting Egypt, being especially interested in that country, several times. They gathered together an important archaeological collection which later was donated by them to the Metropolitan Museum of Art in the city of New York. James Douglas was also greatly interested in photography, a hobby in which he made use of his chemical knowledge. The writer can remember distinctly the descriptions he gave more than forty years ago in Arizona of the difficulties he encountered with the old wet photographic plates, especially while traveling in Egypt, when he prepared and used his own chemicals. In his humorous manner he told how he once discovered, in the nick of time, the nurse preparing to give the baby in the party a rub-down, using for that purpose the white, limpid

Jan 1, 1934

By Christian F. Baiz

INTRODUCTION Industrial minerals can have similar financing requirements to those needs of metaliferrous and coal mining projects. One of the outstanding differences is the understanding of the many different markets that these industrial minerals represent. There are in excess of 30 principal industrial minerals ranging in terms of annual production from the largest quantity such as sand and gravel, to possibly the smallest quantity of production of a legitimate industrial mineral which may be defined as industrial and rough gem diamond. (See Tables 1 and 2) Project finance techniques, analytical methods, and information requirements are covered elsewhere in this Chapter and Chapter 10. Some comments on equity finance aspects follow. EQUITY AMOUNT The amount of equity in a financing transaction provides a cushion to the lender in case the project runs into trouble. Generally speaking, the greater the amount of risk in a project, the more equity a lender will require. The amount of cash equity in a project financing transaction is between 25 and 40 percent. The amount of leverage (debt/equity) is negotiable based on such factors as the strength and extent of the sponsor's undertakings, of the project's economics, and the term of a strong sales contract. Naturally, a borrower seeks to obtain d loan with as little equity required as can be negotiated. Zero percent equity is usually associated with a take-or-pay contract (a hell-or-high- water unconditional commitment under which the purchaser must pay for the commodity as though it were shipped regardless of whether it is actually mined or shipped) with a financially strong corporate entity i.e., the parent company or an end user. As a take-or-pay contract is tantamount to a guarantee of payment, the banker views the credit basis of the loan as being other than the borrower's mining operation and therefore will analyze the creditworthiness of the institution purchasing the commodity on the basis of its corporate balance sheet. Do not confuse a take-or-pay contract with a take-if- tendered or take-and-pay contract. Another means in the United States of obtaining zero percent equity is the carved out production payment financing, typical of coal mine financing. This involves the sale, or conveyance, by the owner of the mineral property of a production payment to a nominally capitalized company. The nominally capitalized company is formed solely to buy the production payment and usually borrows 100 percent of the purchase price from a lender. Equity amounts of 10 to 20 percent generally are found in transactions which employ techniques such as an advance sale or a subordinated lease/loan. These agreements are viewed as quasi equity by most banks for several reasons. First, the proceeds represent a cash infusion early in the project's life - usually prior to the bank lending any funds. Thus, the repayment schedule is "behind" that of the bank debt. In the case of an advance sale, repayment is in the form of a long-term supply contract with favorable terms, usually priced close to the mining operation's costs. There is also usually a requirement that all costs of the project be paid for by the loan or equity, often making the sponsors financially responsible for any cost overruns. Cost overruns are a major risk in any project, large or small, and are often due to unforeseen factors such as wildcat strikes, a piece of faulty equipment, or any event which delays completion, e.g., remote location, weather, etc.. . The question of how overruns are covered can be negotiated. For example, in addition to the original debt/equity ratio of the project, there can also be a cost overrun ratio that will

Jan 1, 1985

The Institute conducts jointly with the American Society of Civil Engineers, American Society of Mechanical Engineers and American Institute of Electrical Engineers, certain activities as listed below, and is joint owner with them of certain properties situated at 29 West 39th Street in New York City United Engineering Trustees, Inc. When Mr Carnegie made his gift, "for the erection of a suitable union home" for the engineering societies, United Engineering Trustees, Inc (then United Engineering Society) was chartered un¬der Chapter 703, Laws of the State of New York, 1904, for "the advancement of the engineering arts and sciences in all their branches, and to maintain a free public engineering library " The Corporation was further empowered to acquire real and personal property and to use, maintain and occupy it, with the provision that any building erected by the Corporation shall be used perpet¬ually as a meeting place and headquar¬ters for the Founder Societies Thus the Carnegie gift realized the ideal of bring¬ing the engineering societies together under one roof, and the Corporation through its members nominated in equal numbers by the four Founder Societies had the necessary authority to act for the Founder Societies in their joint in¬terests in owning and operating for them not only Engineering Societies Building, but in the course of time, Engineering Societies Library, and The Engineering

Jan 1, 1952

By David E. Jones, Dean K. Hunt, C. Y. Chen

INTRODUCTION Of all the numerous geological hazards that threaten the well-being of urban areas in the United States, probably none is so widespread, persistent, and diversified as surface subsidence (HRB-Singer, Inc., 1977). Simply defined, subsidence is the vertical displacement or sinking of the ground surface caused by either natural phenomena or man's activities. The downward movement, however, can be accompanied by horizontal movement, strain, tilt and even by a locally upward movement. Damage to structures and the environment can result from any of these movements. Extracting subsurface materials, fluids and solids, accounts for most man-induced subsidence in the United States. Among all the mining-related subsidences, the collapse of voids created by underground coal mining has been the major cause in inflicting surface damage (Comptroller General of the United States, 1979). Subsidence from coal mining may occur within a few weeks or be delayed for years, depending upon the mineral layer's depth below the surface, the overlying rock strata's characteristics, the extent and methods of mining that were employed, and the time deterioration of pillar and mine structure. Unless underground resources are not mined or control measures are implemented to prevent or minimize damage, some degree of surface subsidence and its accompanied deleterious effects are often inevitable. The ways to control the subsidence and minimize surface damage may include: 1. Precautionary measures built into new structures or surface features. 2. Preventive works applied to existing structures or surface features. 3. Mine design incorporating special underground layouts. 4. Any combination of the above measures. Upon the enactment of Public Law 95-87, the Secretary of the Interior, through the recently created Office of Surface Mining (OSM), was authorized to promulgate rules to regulate mining reclamation including subsidence control. Proposed on September 18, 1978, these rules were finalized, following public comment and hearings, on March 13, 1979, as part of the permanent regulatory program for the regulation of surface mining and reclamation operations which include the surface effects of underground mining. On January 28, 1981, Secretary Watt of the Department of the Interior issued an order to re- quire all agencies to identify with recommendations all regulations which are believed to be excessive, burdensome or counterproductive. Also on February 17, 1981. President Reagan issued Executive Order No. 12291 requiring all Federal agencies to conduct a regulatory review to make a determination that each promulgation of a regulation is clearly within the authority delegated by law and consistent with Congressional intent (Federal Register, 1981). As a result, OSM initiated the regulatory reform to revise the permanent regulatory program. Following a brief discussion of the technical aspects and the effects of subsidence on man and his environment, this paper presents a historical overview of how rules and regulations are used to govern the subsidence related problems. The development of the regulation of subsidence under Public Law 95-87, the Surface Mining Control and Reclamation Act of 1977 (SMCRA or the Act) are also discussed, including the new regulations being developed under the regulatory reform program. SOME TECHNICAL ASPECTS Am EFFECTS OF FINE SUBSIDENCE An extensive historical review of mining subsidence is given by Zwartendyk (1971) and Shadbolt (1978). Comprehensive technical presentations have been given by Henry (1956), King and Whetton (1957), Hall and Orchard (1963). Muller, et al. (1968). Grard (1969), Voight and Pariseau (1970). Kapp and Williams (1972), Cummins and Given (1973), Brauner (1973) , and NCB (1975). A theory of surface subsidence due to underground mining was perhaps first fundamentally stated by a French engineer, Toillez, in 1838, and formulated by a Belgian engineer, Gonot, in 1839 (Goldreich, 1913, cited by Zwartendyk, 1971). Since that time,

Jan 1, 1982

THE man who forgot to mail the letters his wife gave him was for once justified at Tulsa, for envelopes, scratch paper and tablecloths were all in demand and through the two days of the meeting of the Petroleum Division, pencils were busy everywhere sketching out diagrams, drawing curves, figuring, or just taking notes. Those attending took the serious papers seriously, and discussion was wide-ranging but pointed. Despite the highly technical character of the papers presented, the chairmen had never to call for discussion; it was only necessary to say the paper was open for it. Both days the meetings lasted until after five in the afternoon, and it was enthusiastically voted to advance the meeting hour on Friday, in order to give more time. In all, ten papers, abstracts of which appeared in MINING AND METALLURGY for October, and copies of all but two of which were available in print, were presented in the two days, and no more could have been handled to advantage in that time. All but one of these dealt with problems of production engineering. That, the opening paper, was a general review of demand, supply and price in 1928, by Campbell Osborn, in which he argued for the price control of production and showed how the economic conditions determined development. J. Elmer Thomas presented a carefully prepared review of the same data, but came to somewhat different conclusions as to trend, and J. E. Pogue pointed out that in recent years it has been the manufacturing rather than the producing industries that have been notably profitable. These and other discussions were too long to be reported here, but will be printed in full later.

Jan 1, 1928

By C. K. Leith

THE resolution presented at the Annual Meeting of the A.I.M.E., calling on Congress to provide now for postwar accumulation of mineral stock piles under Government control, expresses, I think, the nearly unanimous view of the mining industry. As a result of the trying experiences of the first World War, Mr. Baruch, in his report of Dec. 24, 1919, to the President, urged that steps be taken at once to ensure adequate supplies of raw materials for future emergency. In the twenty years that followed, the same program was vigorously urged on Congress by many individuals and agencies, public and private, including the Secretaries of War and Navy, many members of Congress, the Bureau of Mines, the Planning Committee for Mineral Policy appointed by President Roosevelt, the A.I.M.E., the Mining and Metallurgical Society, and others.

Jan 1, 1943

By Helmut Thielsch

IN recent years an ever increasing amount of interest has been directed toward research studying the principles and various applications of sonic and supersonic waves. Though still in their early stages of practical development, sonic vibrations are already used in the emulsification and degasification of liquids. Metals exposed to sonic or ultrasonic vibrations while solidifying show a considerable amount of grain refinement. Often sound waves are applied instead of radiography to test engineering materials for internal cracks and flaws.1 In the field of pure research these waves are used in dispersion and also in coagulation of particles or liquids in gaseous or, under certain conditions, in other liquid systems. In the settling and thickening of slurries considerable time is necessary to compress the solid particles and to squeeze out the liquid to obtain as low a dilution (liquid to solid ratio) as possible. Various methods have been developed to increase the amount of coagulation of the very fine solids (colloidal or semicolloidal) and to shorten the over-all time. The addition of small amounts of electrolytes and the warming of the suspension represent merely the more important techniques. Some of the effects of supersonic vibrations have been reported previously.2,6 From preliminary studies, therefore, it was hoped that by application of sonic vibrations it would be possible to reduce the time required to thicken such materials to a specific dilution, as well as to thicken to lower ultimate dilutions than could be obtained by quiescent settling alone. By increasing the volume thickened per unit time-i.e., improving the plant efficiency-great savings in equipment and time would be obtained for industrial processes. Also, faster settling rates should result if coagulation of particles could be increased. Experiments have been conducted for a period of several months in the Allis-Chalmers laboratory to study the effect of sonic vibrations on settling of particles of different sizes and concentrations. APPARATUS The sedimentation apparatus used in these experiments is illustrated in Figs. I and 2. The essential features are the stationary field coil and the movable voice coil. Both windings are placed around a solid iron core. A leather diaphragm connected to the steel frame holds the voice coil in place. A brass rod is fastened to the voice coil with a metal disk connected to the other end. This disk is sealed to the lucite cylinder with a flexible rubber diaphragm. The lucite tube is 17 in. long; its inner diameter is 2 ½in. and the wall thickness is ¼ in. The tube is calibrated on the outside in 10 c.c. divisions for a total of 1000 cubic centimeters.

Jan 1, 1946

By J. Rogers, K. L. Sutherland

THE relationships between collector and mineral, activator and mineral, and activator, collector and mineral will be considered herein. We propose to criticize current theories of flotation but we will not repeat the many pertinent arguments presented by Wark and Cox28 in 1937 in which the "chemical" or more strictly the "solubility" theory proposed by Taggart and co-workers22 is shown to be untenable. Recently Taggart, Arbiter and Kellogg24 have studied the long-chain aliphatic amines as collectors and have attempted to resuscitate the solubility theory for these particular collectors. Dean and Ambrose3 have felt that "we stumble over words" when we distinguish different mechanisms of adsorption. Our view is that nothing is more stultifying to the development of a science than attempts to force widely different phenomena into one classification. This oversimplification leads immediately to difficulties in the interpretation of results. EXPERIMENTAL PROCEDURE The response of minerals to activator and collector was determined by "captive-bubble" tests. The methods of preparation of specimens26 and of testing18 have been previously described. Results from captive-bubble tests were confirmed by flotation tests in glass-stoppered cylinders.25 The full lines shown in the figures relating solution composition to contact (flotation) distinguish solutions in which contact (flotation) is possible from those in which it is not. The curve is derived by successive approximation and the accuracy is ±0.2 pH units and ± 5 mg. per liter of collector or depressant. Solution compositions for which it was shown experimentally that contact or flotation is possible are marked by a circle, those for which it is not possible by a cross and those for which it is doubtful by a cross within a circle. It is assumed that at all other solution compositions within (without) the curve, contact or flotation is possible (not possible). After testing in the collector solution, the mineral was removed, washed, and tested by the captive-bubble method in water, or floated in a cylinder with frother only. In this way the composition of solutions in which a mineral was conditioned but in which properties of the collector solution prevented contact or flotation can be defined. The composition of solutions in which conditioning was possible lie between the full and broken curve, the experimental results being indicated on the figures by a square. The curves show the limits of composition of solution in which flotation in a cell would be possible. Many factors other than those considered in these tests determine recovery or grade of a given mineral in practice.

Jan 1, 1947

By Ernest Burchard

A RECONNAISSANCE Of the manganese-and chrome-ore deposits of Cuba was made by the writer, as a representative of the U. S. Geological Survey, in company with Mr. Albert Burch of the Bureau of Mines under instructions of the Secretary of the. Interior, in the Spring of 1918. The object of the study was to obtain authentic information for the use of the United States Government as to the location, character, quantity, and availability of the manganese and chrome-ore deposits in Cuba. Accordingly, the work comprised the examination of such deposits as seemed to be of promise, without regard to stage of development, with a view to determination of the quantity and quality of ore likely to become available for shipment during 1918 and 1919, and of the tonnage of ore in reserve. While it was possible to visit most of the deposits that seemed to be of promise, there was not sufficient time to visit all that were brought to our attention, some of which may have merit. Manganese ore is found in Cuba in Oriente, Santa Clara, and Pinar del Rio Provinces, but in Oriente Province only does it occur in large commercial quantities. There, the deposits are in three areas: one north of Santiago de Cuba, one south of Bayamo and Baire, and one on the Caribbean coast between Torquino Peak and Portillo. In Santa Clara Province, a little ore has been found near the Caribbean coast west of Trinidad; and in Pinar del Rio Province, manganiferous material occurs north of the city of Pinar del Rio and farther west near Mendoza. The manganese ores of Cuba occur, principally, in sedimentary rocks, such as limestone, sandstone, and shale, that are in places metamorphosed, and. in beds that originally may have been water-laid tuff

Jan 3, 1919

By John A. Emery

The Pea Ridge iron ore deposit near Sullivan, Missouri, is a dike-like mass of magnetite enclosed in Precambrian porphyries. The ore body tops at the Precambrian surface at a depth of 1300 feet below the present surface and extends to an unknown depth. It dips nearly vertically, intersecting the dip and strike of the enclosing porphyries at an extremely sharp angle. Faulting, both pre- and post-ore, appears to be of minor consequence, and present knowledge indicates that no preferred structural conditions existed prior to emplacement. The ore body is composed of magnetite with specular hematite, quartz, apatite, and pyrite occurring as accessory primary minerals. Specular hematite in appreciable quantities occurs on parts of the cap and the footwall of the ore body. Fresh porphyry breccia is enclosed in the magnetite along the hanging wall and in the western portion of the ore body. Hanging-wall quartz-amphibole and footwall quartz-hematite occur as replacements of certain porphyries. Further alteration has caused sericitization of parts of these zones. The ore deposit is interpreted as having been formed essentially by a single injection of a magmatic differentiate with hydrothermal end phases forming the quartz-amphibole and quartz-hematite portions of the deposit.

Jan 1, 1968

By J. M. Locke

BRÜCKNER's revolving cylinders for roasting ores, etc., are now used at a number of the mills in Colorado and New Mexico, for the purpose of roasting and chloridizing silver ores, with highly satisfactory results, even from those cylinders of small size, erected before the many improvements of recent date. As examples of the larger improved cylinders, reference can be made to those erected at the Tennessee Reduction Works, Silver City, Grant County, New Mexico, and those which were built, in 1871, at the celebrated Caribou Silver Mill and Mines, Colorado, a mining enterprise which has proved so satisfactory as to have been lately sold to a Holland company for an enormous amount. These cylinders, as now constructed by Messrs. Lane & Bodley, of Cincinnati,, Ohio, are shown in Plate III, in which Fig. 1 is an elevation in perspective, Fig. 2 a longitudinal, and Fig. 3 a trans¬verse section. Fig. 4 is a sketch of a mill, with Brückner's cylinder. The exterior of the cylinder is a shell of boiler iron, 12 feet long by 5 feet 6 inches in diameter. The ends are partially closed with similar material, leaving in the centre a circular opening about 2 feet in diameter, bounded by a flange projecting several inches.. Upon one side is placed an opening closed by a hinged door. Upon the outside of the cylinder are bolted three bands, as shown in Fig. 1, in which the section of the first is square, and that of the third semi¬circular; the second, or middle band, is a strong spur gear. Passing through the cylinder are six pipes parallel to one another, in a plane at an angle of 15° to the axis of the cylinder; these pipes also lie in this plane at an angle of from 30° to 35° to the longitudinal, axis of the plane, as shown in Fig. 2, where the internal arrangement of the cylinder is seen, a perforated diaphragm being formed through part of the cylinder by means of perforated plates placed between

Jan 1, 1874

By Samuel Wyer

F. G. CLAPP, New York, N. Y. (communication to the Secretary*).¬I assume that where this valuable paper states, near its end, that "it is not possible to establish a market price, " the author means that no particular price which will fit all conditions and fields can be given. I am not in agreement with Mr. Wyer, however, that the actual value of natural gas leaseholds is "largely a matter of opinion." I would even be willing to express myself very strongly as believing that if we, as experts, cannot give anything closer than a mere opinion, our testimony or reports are not of great value to our clients. I believe, moreover, that by detailed geological examinations and with our latest knowledge of geological structure, principles of natural gas occurrence, etc., we can approach just as near a certainty in natural gas valuations as we can in oil valuations, and much more so than in the valuation of many metal prospects, in which only the upper few feet of the vein has been opened. In other words, we are getting nearer and nearer every year to bringing geology as applied to oil and gas development into the class of an exact science. Mr. Wyer's paper gives an excellent outline for methods of leasehold valuation. Being presumably intended as an outline only, it can be expanded indefinitely by a detailed discussion of the methods of valuation for the four different classes of leaseholds which he mentions: (A) "Producing;" (B) "Protective;" (C) "Reserve;" and (D) "Prospective." This classification is probably as good as can be made in practice. In the producing leaseholds in particular it is easy to establish a market price at which these leaseholds should be bought or sold. The question would arise in any case whether or not the leases are connected with a pipe line or the distance from the pipe line. Assuming that a pipe line already taps the property and that gas is already being sold for a certain figure, this price must be multiplied by the number of thousand cubic feet still "in sight" in the ground, from which is to be deducted (a) bonuses, (b) rentals, (c) royalties, (d) cost of drilling, (e) taxes and

Jan 12, 1916

By A. W. Furbank

IN reviewing the aerial cameras produced in different countries, it becomes apparent that in nearly all of them an attempt has been made to secure the greatest possible angle of view. This angle, of course, is determined by the objective. The objectives most commonly in use in aerial cameras have a maximum angle of 65°. The objective developed for this new Zeiss camera combines freedom from distortion and brilliant definition, with an angle of 95°. Aerial mapping, it is claimed, has been placed on a different economic basis, and new possibilities presented, par-ticularly in connection with automatic stereoscopic plotting instruments, to which some short references are made. One way of enlarging the angle of view is to couple several instruments with their axes convergent, thereby producing a multilens camera. Typi-cal of cameras of this sort in the United States is the Bagley four-lens camera, which later was developed into the five-lens camera (T3-A) of the U. S. Air Corps. More recently, in order to get away from the unfavorable Maltese cross image field of the five-lens camera, and to obtain a more practical form, two five-lens cameras were combined. By using them in tandem and rotating them by 45° relatively to each other, a ten-lens camera was produced, covering an octagonal ground area, with a total angle of view of 140°. Similar designs have been evolved in other countries. In all of them, however, a number of difficulties have arisen, quite apart from their large weight and high cost. Because of their complex mechanism, numerous shutters and magazines, and the high precision with which these parts must be interadjusted and synchronized, these cameras are far from dependable. Moreover, a multilens camera by itself does not yet constitute a complete outfit for producing pictures suitable for photogrammetric survey. Because all the component pictures, except the central one, are obliques, it is always necessary to employ rectifying apparatus which transforms the marginal views to the perspective of the central one. In multilens cameras with many individual magazines, it is not convenient to

Jan 1, 1938

With only one certain exception coal was never used by the Indians, before white men came to America, for any purpose except as an ornament or for paint. Within the past few years it has been discovered that the Hopi Indians in Navajo County, Arizona, used lignite for burning pottery, about 1000 A. D., as dated by tree rings. They were able to obtain a clear color in their ware that could not be obtained with brushwood fires. The coal was mined by hammers from outcrop openings, some of which can still be seen, and the tools used have been found in them.1 (See also p. 376.) Small figurines made of splint or cannel coal have been found at various localities in western New York, in Ohio and possibly other places, evidently made for ornaments. There is no reason to think they are of any greater age, if as old, as that mentioned above. Some crushed coal was used by the Indians as a black pigment in painting themselves, but apparently the eastern Indians never used coal for any other purposes. Some think that several tribes of Indians in the Northwest, along the Missouri, used coal as fuel, the basis being a statement attributed to Radisson about 1660. In the Jesuit Relations of 1659-1660 it was stated that Radisson anti Groseilliers had just returned from a visit to Lake Superior and beyond. "In the country of the Poualak, which means 'warriors' they say `as wood is scanty in supply and small in size in their country, nature has taught them to make fire with coal from the earth (charbon de terre) and to cover their cabins with skins.'"2 This statement was only hearsay with the good fathers, and the reputation for veracity of the two explorers is not of the best, and it is extremely probable that instead of coal they used turf, dry grass or buffalo chips. In fact in Radisson's Voyages' he does not mention coal at all in his account of the third voyage, when he was supposed to have seen it used. His accounts of his travels are badly mixed, and he and his companions were much better travellers than narrators. None of the early travellers up the Missouri River saw any evidence even then that the Indians were familiar with the use of coal. In the writer's opinion it is unlikely that coal was used as stated by the Jesuits.

Jan 1, 1942

By Frank Robertson Van Horn

In June, 1911, the writer spent a few days in studying the economic geology of the vicinity of Park City. During this rather hurried visit a number of specimens of ore were collected, which have since been examind. The results of these investigations show that bournonite (PbCu-SbSa) is present in the ores in greater or less quantity. This fact has never before been reported, as far as can be learned. The failure to recognize this mineral is due to its similarity to tetrahedrite, with which it has probably been confused during a long period of years. Jamesonite (Pb2sb2s6) has been reported from the region in a rather doubtful manner, but the writer has seen it in notable amounts from several mines, and can offer the first analysis of this mineral from the district. Calamine (HzZn2SiO5) was found at one mine and has never been ecognized and reported from the district. Geogbaphy and Geology Park City, Utah, is located at an elevation of about 7,000 ft. above sea level on the eastern slope of the Wasatch mountains. It is situated approximately 25 miles southeast of Salt Lake City. ' The geology and ore deposits have been described in detail by Bout well and Woolsey.' The mines visited are situated south-southeast from the town. The Silver King Coalition mine is located in Woodside gulch about 1 mile southeast of Park City, at an altitude of about 8,100 ft. The other mines visited were the Daly West and Quincy, which are in Empire canyon about 2 miles sontheast of the town, at elevations of 8,300 to 8,500 ft. respectively. The Daly Judge tunnel goes into the mountain from Empire canyon about 1 mile south of the city, at an altitude of 7,700ft.

Jan 1, 1915

By Wittenau, E.

OPERATION of a pilot mill of 100 tons' daily capacity during 1930 and 1931 proved that the copper minerals of the Colorado and Clay sections of the Morenci ore body could be successfully concentrated by the flotation process. Economic conditions caused postponement of further testing work until late in 1938 when the former No. 6 Concentrator at Morenci was converted into an experimental mill of 1500 tons' daily capacity which was known as the Test Concentrator. The Test Concentrator began continuous operation on April 3. 1939, using such crushing and grinding equipment of the No. 6 Concentrator as was appropriate. Modern classifiers and certain flotation machines were installed and later other types of flotation machines, a large grate-type grinding mill. mechanical screens, a short-head cone crusher, and a disk filter were added to the test equipment. Operation was uninterrupted until Dec. 31, 1941.

Jan 1, 1942