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By T. A. Rickard

In southeastern France, among the magnificent alpine masses of the Dauphine, there is a group of celebrated mines of silver-, nickel- and cobalt-ores, the deposits of which present many features

Jan 1, 1895

By A. J. Griest, J. C. Danko

IN the course of vacuum evaporation experiments, sublimation figures were observed on the surface of a pure nickel specimen. A cubic figure, typical of those observed on this specimen, is illustrated

Jan 1, 1957

By J. W. Stewart

The aim of this paper is to point out the various ways in which design is taught in standard four-year mining engineering curricula in American colleges and universities; to discuss the reasons apparently justifying the great diversity of procedure that exists along this line; and to indicate possible solutions to the difficulties now attending the teaching of design. A study was made of typical four-year mining engineering curricula in 15 colleges and universities of the United States (Table I). Great diversity in content of the various design courses, if taught as described, became apparent immediately. It appeared that it might be both interesting and instructive if the cause for this colorful variety could be found. Was the cause local mining conditions, departmental individuality, or actual necessity? Study of the school catalogues revealed that the various design courses could be classified into two fairly distinct types; namely, (I) those dealing with mine equipment or structures, and (2) those dealing with underground layout of mine workings. It seemed reasonable to label the first type of course "mining design" and the second type "mine design." Some such distinction must have been in the minds of mining educators, for we find both names (i.e., mine design and mining design) used to designate the design courses included in the various mining curricula Unhappily, the name and the apparent content of such courses do not, in all instances, conform to the classification made here, although in most instances such conformation does obtain (Table I). It is possible that in the exceptional case the method of teaching a design course, and consequently the content of it, may have been changed at some time without change in the name of the course. Apparently only 3 of the 15 schools made an effort to cover both types of design in their curricula (Table I). Two other schools did not list or describe any course of study that could with certainty be taken as a design course. Of the remaining 10 schools, 9 gave a mining-design type of course and one gave a strictly mine-design type. Obviously, the preponderance of design courses afforded are of the mining-design type. Why? To answer this question, it is necessary to make a study of the prerequisites for the two types of design courses taught. In all schools the design courses were taught in the senior year; in eight, design was taught throughout both semesters; in two, it was taught during the first semester only; and in three it was taught during the second semester only. Consequently, excepting the last three cases noted, it is obvious that all prerequisites for a design course should be completed by the end of the junior year PREREQUISITES What are the probable prerequisites for the different kinds of design courses as they appear to be taught? Let us take first the case of the mine-design type of course, having to do with layout of underground workings. Here it would seem that logical

Jan 1, 1943

By J. W. Stewart

The aim of this paper is to point out the various ways in which design is taught in standard four-year mining engineering curricula in American colleges and universities; to discuss the reasons apparently justifying the great diversity of procedure that exists along this line; and to indicate possible solutions to the difficulties now attending the teaching of design. A study was made of typical four-year mining engineering curricula in 15 colleges and universities of the United States (Table I). Great diversity in content of the various design courses, if taught as described, became apparent immediately. It appeared that it might be both interesting and instructive if the cause for this colorful variety could be found. Was the cause local mining conditions, departmental individuality, or actual necessity? Study of the school catalogues revealed that the various design courses could be classified into two fairly distinct types; namely, (I) those dealing with mine equipment or structures, and (2) those dealing with underground layout of mine workings. It seemed reasonable to label the first type of course "mining design" and the second type "mine design." Some such distinction must have been in the minds of mining educators, for we find both names (i.e., mine design and mining design) used to designate the design courses included in the various mining curricula Unhappily, the name and the apparent content of such courses do not, in all instances, conform to the classification made here, although in most instances such conformation does obtain (Table I). It is possible that in the exceptional case the method of teaching a design course, and consequently the content of it, may have been changed at some time without change in the name of the course. Apparently only 3 of the 15 schools made an effort to cover both types of design in their curricula (Table I). Two other schools did not list or describe any course of study that could with certainty be taken as a design course. Of the remaining 10 schools, 9 gave a mining-design type of course and one gave a strictly mine-design type. Obviously, the preponderance of design courses afforded are of the mining-design type. Why? To answer this question, it is necessary to make a study of the prerequisites for the two types of design courses taught. In all schools the design courses were taught in the senior year; in eight, design was taught throughout both semesters; in two, it was taught during the first semester only; and in three it was taught during the second semester only. Consequently, excepting the last three cases noted, it is obvious that all prerequisites for a design course should be completed by the end of the junior year PREREQUISITES What are the probable prerequisites for the different kinds of design courses as they appear to be taught? Let us take first the case of the mine-design type of course, having to do with layout of underground workings. Here it would seem that logical

Jan 1, 1943

By N. V. Peterson, R. S. Mason

Pumice, pumicite, and cinders are all products of explosive volcanic eruptions. Pumice and pumicite are produced by the violent expansion of dissolved gases in a viscous silicic lava such as rhyolite or dacite. Pumice is a light-colored, cellular, almost frothy rock made up of glass-walled bubble casts. It may occur as coherent, massive blocks composed of highly vesicular glassy lava in either a flow or vent filling, or it may be more or less fragmented by violent eruption. Pumicite has the same origin, chemical composition, and glassy structure as pumice differing only in particle size. Particles less than 4 mm in diam are designated pumicite. Pumice is usually found relatively close to the vent from which it was erupted while pumicite may be carried by winds for great distances before settling as an accumulation of fine-grained ash or tuffaceous sediment. Volcanic cinders are the reddish to black vesicular fragments that pile up during explosive eruptions of volcanoes of basaltic composition. Most deposits of cinders occur as cones or mounds of stratified fragments that range in size from a fraction of an inch to several inches in diameter. Individual cones or mounds of cinders may be several hundreds of feet in diameter and as much as 500 ft high. Properties The properties that make pumice and pumicite useful in industrial applications include: low-bulk density, good heat and sound insulating properties, and excellent abrasive capability. Cinders, even though less cellular and somewhat heavier, also have a variety of industrial uses. Uses The main use of pumice and cinders continues to be in the construction industry as road-surfacing material, railroad ballast, building block aggregate, in lightweight structural concrete, and as plaster aggregate. Both pumice and pumicite continue to be used as abrasives for polishing glass, metal, leather, stone, and wood. Some scouring powders and soaps also contain pumicite. Minor uses include fillers, absorbents, carriers for insecticides, catalyst carriers, filters, and soil conditioners. Pumicite is also used in sizable quantities as a pozzolanic additive in monolithic concrete where it increases the workability, strength, and durability of the concrete and reduces the heat of hydration. Volcanic cinders are generally denser and more coarsely cellular than most pumice. Markets for cinders include aggregate for road construction and surfacing and in lightweight concretes, particularly blocks. Some producers having access to both pumice and cinders offer a variety of blends of the two materials to block manufacturers. Most pumice deposits are unconsolidated and usually have a minimum of overburden. Mining is by open pit and can be easily carried out with conventional loading equipment. Sometimes air-drying precedes hauling to a crushing and screening plant which yields the size product desired. Multiple bins at railroad hauling facilities permit blending if desired. Pumice for abrasive use may require more sophisticated processing by fine grinding and air classification before being bagged for market. Block pumice in economic quantity and quality is limited to a few geologically young

Jan 1, 1975

By C. G. Southmayd

ANYONE who has been confronted with the problem of predicting the performance of a sand-pump installation is vitally aware of the dearth of precise information that has been published on this important subject. Such data as have been collected are not readily available in a concise and readily usable form, so that many operators would find it a considerable chore to find the pertinent information required to undertake a detailed study. The purpose of this paper is to assemble such established data, correlate them with field experience and outline the factors that must be appraised in the determination of a satisfactory pump installation. The transportation of solids in solution is of vital interest to every mill superintendent and operator, and many of the factors that are involved in this hydraulic problem vary widely from installation to installation, and in some cases even from time to time on any one installation.. These include: type of solids (including shape of particles), size of solids (grind), percentages of fines (slimes), dilution of pulp, contour of pipe line, type of pipe, age of pipe line, effect that diameter of pipe has on characteristic flow conditions, and other factors. Some of these have been fairly well determined by experimental work but many still must be established through interpolating or extrapolating between values that have been derived from known field conditions. Most problems primarily concern the transportation of a definite weight of dry solids from one specific location to another. The type of material, shape of particles, grind and percentages of fines are established and very often the dilution at which the solids must be handled as well. The problem then evolves into a determination of the size, type and contour of the pipe line and the net effective head against which the pump must operate. Before discussing the determination of the head, it might be well to review the interrelationship between the pump discharge (capacity), the head developed by the pump and the pump speed, which will apply to any centrifugal pump installation. EFFECT OF PUMP SPEED Basically, the head developed by a centrifugal pump varies as the square of the pump speed and the discharge as the first power of the speed. However, even at constant speed a centrifugal pump will operate over a wide range of capacities, depending upon the head that must be developed to deliver the liquid or pulp to the end of the pipe line. This is shown graphically in Fig. I. If the pump in question is being driven at a constant speed of 900 r.p.m. it will deliver 500 U. S. gal. per min. against a head of 56 ft., 800 U. S. gal. per min. against a head of 50 ft., and so on. In other words, at this speed the capacity of the pump will be determined and limited by

Jan 1, 1946

By R. H. Jacoby, V. J. Berry, R. C. Koeller

The experimental phase behavior of several field gas-condensate systems, one field volatile oil system, and a series of synthetic systems having gas-oil ratios from 2,000 to 20,000 scf/bbl stock tank oil was measured. The data were used to calculate the depletion performance of the field systems at their respective reservoir temperatures and of the synthetic systems at various temperatures. The results of the performance calculations were used to prepare correlations of total stock tank oil and separator gas in-place, and the amount of each recovered by primary depletion. Data needed to use the correlations are initial gas-oil ratio, initial tank oil gravity, reservoir temperature and reservoir pressure. The correlations presented should be useful for estiinating recovery from reservoirs producing volatile oils or rich gas condensates having gas-oil ratios from about 2,000 to 30,000 scf/bbl of stock tank oil. INTRODUCTION Prediction of depletion performance for gas-condensate reservoirs usually requires extensive laboratory work or lengthy phase-behavior calculations. For many small gas-condensate bearing zones the expense of such work is often not justified. Furthermore, where large holdings are involved, it is useful to have estimates of future oil and gas production in advance of the results of a laboratory analysis, even if such work is ultimately planned. For these reasons, it would be of value to have a method for rapidly estimating the depletion performance of gas-condensate reservoirs from the type of field data usually available. Few data on the reservoir depletion performance are available for the purpose of developing correlations. The increasing number of gas-condensate discoveries and the advent of high-speed computers have stimulated the development of methods for predicting performance. Such calculated performance data have been shown to be reliable and are becoming accepted as a basis for reserve estimates and for engineering studies. It therefore seems satisfactory to use results of performance predictions themselves for the purpose of developing the desired correlations. Such an approach is described in this paper. Several rich natural gas-condensate systems (gas-oil ratios of from about 3,600 to 60,000 scf/bbl) and one natural volatile oil system were studied (2,363 scf/bbl). In addition, to provide a more systematic basis for correlating purposes, a series of related, synthetic reservoir fluid mixtures was also studied (GOR's from about 2,000 to 25,000 scf/bbl). The purpose of this paper is to show how the recovery of oil and gas by primary depletion may be estimated from surface gas-oil ratio, reservoir temperature and pressure, and tank oil gravity. procedure Experiments Companion samples of gas and oil were collected from the high pressure separators in nine different fields at the time of their discovery. These samples were each recombined in accordance with the respective producing GOR to reproduce the reservoir fluids. Eight of these fluids, designated F-2 through F-9, were rich gas-condensate systems at the respective reser-

By AIME AIME

ELECTRICAL methods of geophysical exploration attracted major attention at the three sessions devoted to geophysics on Monday and Tuesday. At the opening' meeting Monday morning Hans Lundberg gave the paper by himself and Folke Kihlstedt; he described the use of the Racom, discussed last year, and the method whereby it is possible to eliminate all but subsurface, effects in electrical exploration. In the discussion Theodor Zuschlag pointed out some of the theoretical considerations behind the field procedure. Karl Sundberg's paper on the effect of impregnating waters was presented by title only, and S. F. Kelly then gave an abstract of a paper on the electrical properties of ores, by J. J. Jakosky, R. N. Anderson and Clyde H. Wilson. , This dealt with an exhaustive series of laboratory tests on the variation of -conductivity of ore specimens with the frequency of the energizing current, and of the effect of moisture content in typical clays and gouges on their conductivities at various frequencies. Considerable discussion was provoked during which the authors came in for some-criticism on their measuring circuits and for their assumption that a solid conductor could be compared with linear ones. They were praised, however, for making a start toward a compilation of resistivities for ores and rocks. Dr. Slichter disagreed with them that the conductivity of an orebody was primarily capacitive. He also called attention to the fact that it was high time geophysicists adopted the standard physical expression of ohm-,centimeters or ohm-meters to express resistivities. This same point was the burden of the next paper,. "Uniform Expression for Resistivity," by Sherwin F. Kelly, presented by title only.

Jan 1, 1932

By O. B. Hopkins

DuRing 1931 Peru lost its place as ninth among the oil-producing countries of the world, to Argentina, and even in tenth place its production only slightly exceeded that of Trinidad. The preliminary figures for 1932 indicate that Peru will lose tenth place for that year to Trinidad. The production in barrels of the three coastal fields of Peru during the past three years was as follows: In addition to this crude production, the International and Lobitos companies produced approximately 770,000 bbl. of casinghead gasoline during 1932. There was no outstanding development in the oil industry in Peru during 1932; activity in the fields was very much restricted due to curtailment of production and the low price of oil. The potential production of the property of the International Petroleum Co. Ltd. greatly exceeded the actual production. By the beginning of 1932, a total of 2348 productive wells had been drilled on the property of the International, of which 547 had been abandoned, leaving 1801 productive wells at that' date. These wells cover a total productive area of approximately 13,500 acres. The crude produced has an average gravity of 37° to 38° Be. The Lobitos crude is of approximately the same gravity. The earliest oil pool developed in the Peruvian Coastal area is now more than 40 years old and is still producing. The major development in the area took place between 1920 and 1930. Production at the present rate can be maintained for 10 years or more.

Jan 1, 1933

By E. V. Given

In speaking of the concentration of oxidized lead ores at St. Anthony, I do not wish to infer that we believe all lead ores of a similar grade can be mined and treated at a profit. Our oxidized ore is low grade, and certainly the mine under present economic conditions could not operate on this ore by itself. Because of favorable conditions we can operate the oxide circuit at a small profit although we do not allocate overhead, pumping, and certain other general charges to it. Operations in the oxidized zone were started as an essential part of the development necessary to outline and mine the sulphide ores. Nearly all of our oxidized lead ore comes from the Collins section of the mine, with the transition from oxide to sulphide ore lying between the 600 and 700-ft levels. Production from sulphide ore is much larger than from the oxide, both in tonnage handled and in grade of ore. The oxide and sulphide ores are never mixed either in the mine or the mill. The oxide mill sections have their own ore bins, grinding, and flotation departments. The lead minerals contained in the ore, in the order of their importance are cerussite, wulfenite, galena, anglesite, and vanadinite. The ratios of the different lead minerals change as the ore is pulled from different parts of the mine-total lead being approximately 50% to 60% cerussite, 20% wulfenite, 15% galena, zero to 10% anglesite, and 2% vanadinite. About 3% of the lead was unidentified.

Jan 5, 1950

By R. P. Rothwell

THE first difficulty mentioned is that in some instances two or more beds of coal separated by sandstone or slate rocks of considerable thickness in one part of a basin, are found running together in another part. Of course, we may happen to strike first the part of the basin where there is but a single seam, and in this case the bed would appear 60 divide into two or more branches within a short, distance. Such cases are not rare in the anthracite coal-fields. I would suggest as an explanation of this phenomenon the gradual sinking of the peat-marsh-the embryo coal-bed-on one side, and the moving forward of the marsh, so that on one part of the bed the formation of peat would still be progressing, while another part, being under water, would be covered with mud and sand. Thus we have different portions of the same bed of different ages. Now if the sinking of the marsh be stopped for a time, the bed will become thicker in the portions left exposed, and if the sinking now changes in direction, so that the part that had previously gone down commences to rise, we should have the phenomenon of a bed, continuous throughout, with one portion overlying another, and separated from it by rock strata. These are exactly the conditions observed in splitting beds. While one side of the lake is sinking, and the peat marsh moving on in that direction, the other side may be rising,

By Charles Catlett

An examination of the census reports' for 1880, which contain a large number of complete analyses of typical American iron-ores, indicates that the existence of barium sulphate in intimate association with iron-ore is rather unusual. Of 94 analyses reported there, but four show any barium sulphate, and the maximum content amounts to 3.04 per cent. The note of the occurrence of considerable quantities of barite in connection with certain iron-ores found in the Pinar del Rio Province of Cuba may be of interest. These deposits are found near the little village of Francisco, about 25 miles west of the city of Pinar del Rio on the Western Railroad of Havana. The principal ridges are anticlines, and consist of very thick deposits of sandy shales and slates containing a large number of little veins of white quartz, which, by the gradual disintegration of the mass of the material, is left covering the surface. This quartz occasionally shows sulphide, but is generally barren of any such indication. At times lenticular masses of a more or less pure limestone mere observed in these slates. The shales, which are of light color, are occasionally talcose. The formation would tentatively be classed as the Lower Cambrian, arid the heavy ridges of comparatively horizontal limestone found in the anticlinal valleys as the Upper Cambrian. Along the crest of these slaty ridges deposits of iron-ore are found which are apparently in place, and were probably formed by replacement of masses of limestone similar to those noted elsewhere. The ready disintegration of the slates, arid the

Jan 1, 1908

Discussion of the paper of H. H. STOEK, presented at the St. Louis meeting, October, 1917, and printed in Bulletin 129, September, 1917, pp. 1385 to 1419. J. B. WARRINER, Lansford, Pa. (written discussion*).-The figures on costs given at the end of this paper. are of particular interest and it is unfortunate that they necessarily cover such limited periods, as figures giving the costs over a period of at least a year would be of much greater value; for instance, it seems hardly probable that the performances credited to the various shovels for the months for which the costs are given would represent the average of the performances of these machines over a longer period. It would seem to me that the maximum of 4000 cu. yd. (3058 cu. m.) per clay given for the 225 B shovel is much greater than could be maintained for an entire year's operation. On the other hand, the 1500-yd. figure for the 150 B shovel would seem a low average for this type of shovel. In connection with the drag-line excavators, it will be interesting to know that the Lehigh Coal, and Navigation Co. is about to install one of these machines on a clay stripping at their Nesquehoning colliery to excavate an average depth of. overburden of 65 ft. (19 m.), which, due to local conditions, will require that part of the excavated material be handled a second time and a lesser quantity a third time. The results of this operation will undoubtedly be watched with great interest.

Jan 1, 1918

C. A. Stetefeldt, San Francisco, Cal. (communication to the Secretary): In view of Mr. Louis's statement that the balance and weights employed in his experiment were '(by no means first-rate," the results can scarcely be entitled to weight. And if a slight variation in specific gravity were to be accepted as proof of the existence of allotropic modifications, we should be obliged to conclude that every metal existed in such modifications. When the observed specific gravity of an alloy (as is often, and perhaps generally, the rase) differs from the calculated one, it seems more reasonable to explain the difference (apart from errors of determination) by assuming that actual chemical combination takes place between some atoms of the metals. MR. Louis (communication to the Secretary): In reply to the criticisms with which Mr. Stetefeldt has favored me, I beg to point out to him that, in the first place, I do not myself attach very much weight to the results I have obtained. I merely claim to have pointed out that amorphous gold obtained from dissolving up the alloy with silver has a higher specific gravity than common gold—a result corroborated by the quoted results of Rose. At any rate, it is easy to repeat my observations, and I hope this may be done by men who have better opportunities than myself for this investigation. Surely it is worthy of attention from assayers at the mints. I am not prepared to say that I should regard slight variations in specific gravity as absolute proof of allotropism, but I do consider

Jan 1, 1894

By O. B. Hopkins

The total production of oil in Peru in 1940 was 12,127,135 bbl., or about 10 per cent less than in 1939. Most of the reduction can be attributed to the fact that the export market under war conditions is much restricted and naturally is more than ordinarily competitive. Development and Exploration in Older Areas As evidenced by Table I, almost all production continued to come from the three established fields in coastal northwestern Peru. Zorritos Field.—Exploration in this small field, which was purchased by the Peruvian Government in 1939, continued with that in near-by areas in the adjoining National Reserve. Several wells were drilled, regarding which details are not as yet available. It is estimated that the production rate for a total of some 45 old and 15 new wells approximated zoo bbl. per day, or about 3 bbl. per well per day. Lobitos Fields.—The Lobitos area produced 2,435,504 bbl.; about 10 per cent less than the amount for 1939. La Brea-Pari9zas.—This property of International Petroleum Co. continued to account for nearly 80 per cent of Peru's production. During the year, drilling was stepped up to 139 wells, as compared with 73 wells completed in the previous year; 123 were producers and aggregated a total of 287,867 ft. Of this total, more than 85 per cent was drilled by rotary tools, which are steadily displacing other equipment. Although most of these wells were drilled in the proved or semiproved areas, eight

Jan 1, 1941

ROBERT E. TALLY,* Jerome, Ariz. (written discussion ?).-Mr. Sherman's paper, entitled "Measures for Controlling Fires at the Copper Queen Mine," embodies two new and very important features: First, automatic closing of doors communicating with the dangerous area; second, the use of a portable storage-battery fan. His other procedures, such as giving a general fire alarm, getting workmen to the surface, etc., are equally important, but have long been in use in other places. Fire and ventilating doors in connections leading to shafts, air raises, and other large timbered areas, have been in use at other mines; but the method described by Mr. Sherman for operating these doors by compressed air, through a valve on the surface, is, so far as I know, original, and should be installed in every mine where there is danger of fire. Nearly all large mines are now using artificial ventilation, with the result that there are strong air currents in the shafts and other important workings. The most important feature in mine fires is a quick and positive control of the ventilation, for it takes but a few moments for smoke to travel over a large area, with the usual results of suffocation, and destruction of property. A strong air current in an upcast shaft acts as a draft in case of fire, and unless quickly cut off the fire would soon get beyond control. An upcast shaft usually changes to a downcast when large amounts of water are used. Human lives are in more danger from downcast currents, as the smoke travels into the workings.

Jan 4, 1918

By O. B. Hopkins

The total production of oil in Peru in 1940 was 12,127,135 bbl., or about 10 per cent less than in 1939. Most of the reduction can be attributed to the fact that the export market under war conditions is much restricted and naturally is more than ordinarily competitive. Development and Exploration in Older Areas As evidenced by Table I, almost all production continued to come from the three established fields in coastal northwestern Peru. Zorritos Field.—Exploration in this small field, which was purchased by the Peruvian Government in 1939, continued with that in near-by areas in the adjoining National Reserve. Several wells were drilled, regarding which details are not as yet available. It is estimated that the production rate for a total of some 45 old and 15 new wells approximated zoo bbl. per day, or about 3 bbl. per well per day. Lobitos Fields.—The Lobitos area produced 2,435,504 bbl.; about 10 per cent less than the amount for 1939. La Brea-Pari9zas.—This property of International Petroleum Co. continued to account for nearly 80 per cent of Peru's production. During the year, drilling was stepped up to 139 wells, as compared with 73 wells completed in the previous year; 123 were producers and aggregated a total of 287,867 ft. Of this total, more than 85 per cent was drilled by rotary tools, which are steadily displacing other equipment. Although most of these wells were drilled in the proved or semiproved areas, eight

Jan 1, 1941

By J. PARK

Discussion of the paper of J. PARSE CHANNING, presented at the New York meeting, February, 1915, and printed in Bulletin No. 99, March, 1915, pp. 529 to 538. FRED H. RINDGE, JR., * New York, N. Y.-It is interesting to note that although this movement was started only seven years ago at Yale, it has spread in that brief time to 200 colleges and technical schools, anti thousands of men are interested in it. There are 3,000 graduates who became acquainted with the movement in college days anti are now promoting the industrial betterment idea all over the country. Some of these men are employed entirely in this work, and the number of such workers is constantly increasing. We feel we are really doing a very fundamental thing in getting so many coming engineers and prospective employers of labor to interest themselves in these things which we have been discussing this morning; these things which are so vital to efficiency and success in any line of business or engineering to-clay. Of course the institutions located in our large industrial centers have the greatest opportunity for practical service. But I have just returned from one college, Pennsylvania State College, where 300 engineering students in three clays signed up as interested in this movement and as anxious to take active part in the work this summer. That is one of a number of colleges situated in towns where there are 110 industrial opportunities. Therefore, their field of service must be where they work

Jan 5, 1915

By E. Gybbon Spilsbury

It is not my purpose in this paper to describe all the different contrivances which have been devised, during the last quarter of a century, for the purpose of Iessening the expense of mining and tunnelling operations; I wish merely to call your attention to the crying want of the Western miners for some cheap and effective machine, capable of economizing on the heavy item of hand-drilling, and to enumerate a few of the latest improvements which have been made in machines of this class. This necessity for the introduction of some kind of labor-saving machinery in mining, especially in the West, begins to make itself felt more imperatively every day. No branch of industry has remained so conservative to the old customs and systems of working, as has mining; and yet no branch is so entirely dependent on economical working for a successful issue; and in very few is the proportion of cost of hand-labor to profits obtained so preponderantly heavy. Perhaps the chief reason for this seeming apathy towards progress in this direction arises from the fact that nearly all mining operations, especially in this country, are carried on in regions more or less remote from the great centres of civilization, thereby rendering the carriage and erection of machinery extremely difficult and expensive. Another reason, however, exists in the fact that a large number of men in charge of mining operations are greatly prejudiced against the introduction of machinery underground, from the idea that it cannot be made to adapt itself to the various positions and

Mr. Cottrell : I omitted to speak of the cost of installation. The precipitation-plant at the Balaklala smelter, up to the time of initial operation, including the construction of flues, installation of the apparatus, etc., cost $107,000, and subsequent modifications probably represented at least $15,000 more. Upon the information gained in this plant, the installation at the cement-mill, handling nearly twice as much gas, has been reduced in cost in a number of ways, but the overhead construction, carrying the precipitator at the top of the stacks, is naturally expensive, yet, even so, the total cost of construction will probably not greatly exceed $150,000. The mechanical details of the tubular form last shown have been worked out more recently than those of the plate form, and the tubular form promises to be still less expensive in construction, as you would naturally expect. The cost of operat-ing the plant varies somewhat with the character of the gases used. The amount of power consumed is not determined by the tonnage of the material collected, but by the volume of gas to be handled. It takes as much power to precipitate a thin cloud as a dense one. In the cement-plant they are getting a higher efficiency; i. e., a greater number of cubic feet treated per kilowatt than in the earlier plants. This is perhaps partly due to higher temperature of the gases, which here average about 450° C. The best figures on the cement-plant are between 3 kw. and 4 kw. Of

Jan 1, 1913