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By S. W. Farnham

Those who remember the years of patient effort and the slow results obtained in the first introduction of electrical coal cutters and locomotives will, I think, admit that mechanical loading of coal is unquestionably being established at a much more rapid rate than any previous application of machinery to reduce manual labor in mines. There are many operators who consider the progress of the loaders today as slow, but considering the number of years it took to thoroughly establish electrical coal cutters and locomotives, and comparing it with the short time that the mechanical loader has been on the market, and the results that have been obtained today, they will admit, I think, that the progress of the latter is much more rapid. It is about 35 years since the advent of the electrical coal cutter and electric locomotive. Their use has brought about these improved conditions, increased tonnage per mine and other features, which are of assistance to the installation of mechanical loaders. The management and the technical staff in practically all of the American mines are trained in the use of electrical machinery and understand its operation, care and maintenance. . There is frequently, a surplus of electrical power and wiring available to take care of the small requirements of the electrical loader. The mechanical loader, therefore, starts today with the ground prepared for it. Those manufacturing companies who have had years of experience in the design and construction of mining machinery, know in a large measure what to incorporate in their designs to make the parts of the new type of machine effectively strong and to operate with efficiency under the severe conditions encountered in mining service. All these advantages greatly assist the success of a new type of machine such as the mechanical loader. In spite of these advantages, however, there are bound to be some failures. All new types of loaders have to be developed. We hear of some that are a success and some that are set aside. The field of application of each type and its limitations first must be determined by actual operation. The earlier loaders had to be changed and improved in design as weaknesses developed. Not all of the new types of coal loaders have been built by mining machinery manufacturers of long experience, and the lack of experience in this line is responsible for some of the early failures. The coal mining company staffs and also those of the loader companies had to learn what the operating factors were that made mechanical loading a success. The difference in results obtained by loaders in different properties under similar physical conditions indicates that the mine management is a very large, if not the major factor, affecting the efficiency of mechanical loading. Many articles have been written on the question of loading. The subject has been quite fully discussed at recent coal meetings and in the technical press. It is not always as easy or simple a matter to form conclusions as may first appear as to one's own particular loading problem. Mechanical loading is a comparatively new art, and many companies while claiming that loaders are quite successful, do not have an accurate line on the actual saving they are affecting. Many of them have only a few of the factors taken into account in their costs. Many loaders have been generally bought without very careful consideration given to all details and except where extremely favorable conditions prevail, failure resulted. When contemplating the installation of mechanical loading, one naturally desires to select the type of loader that will, fit his mining conditions. The things

Jan 1, 1924

It was said that the coal operators are losing a great advantage in permitting the oil producers to take the domestic market away from them. Coal is so much less expensive and more economical than oil that even the oil producers themselves are burning coal under their stills. No longer is the housewife afraid of machinery. Not only does she operate an automobile, but in her home she is used to vacuum sweepers, washing machines, refrigerators, and multitudinous devices. She is no longer machine-shy. An electrically operated stoker, if properly introduced and guaranteed with only a fraction of the enthusiasm that the oil furnace salesman shows, would get a ready reception. Several devices now on the market are much less complicated, much less apt to get out of order, than the oil burners. In place of an increased cost for the sake of convenience, the stoker will give all this convenience at a decreased cost. So said Mr. Herres. He said, however, that it must be enclosed so that the working parts are not too much in evidence. MR. McAULIFFE: While it appears possible to adapt a continuous feed to the needs of the furnace in an apartment or a house burning thirty tons or more annually, it is not yet possible to get a furnace that would satisfy the home which burns only seven or eight tons in a season. A delegate described the Garrison stoker which is designed to care for this problem. Mr. Herres said that the Pacific Coal Company had a small stoker furnace more simple than the Harrington. Pulverized coal equipment is being adapted to use in apartment houses. The stoker designed by Lloyd Garrison, State Engineer of Utah, was described, and also one which Mr. G. W. Megeath of Omaha, Nebraska, had manufactured, which Mr. McAuliffe says, is recommended only for Rock Springs coal. It was brought out that there are over forty installations of the "Iran Fireman" in Salt Lake City. For apartment buildings, there is no question as to their satisfaction. Many of the down town office buildings are so heated.

Jan 1, 1925

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Jan 1, 1982

By E. H. McCleary

The Alamo Mine The Alamo mine is located about seventeen miles northwest of Walsenburg, Colorado, on the Loma Branch of the Denver and Rio Grande Western railroad, in the foothills of the Black Mountains of Huerfano County. Prospecting Mr. W. B. Lewis of New York City, president of the Oakdale Coal Company and also president of the Alamo Coal Company first became interested in this property in 1920. After all natural features of the surface had been carefully examined by Mr. Lewis, he was convinced that the property was underlaid with coal seams. Plans for prospect drilling were made at once and this drilling was started late in 1921. In all, eight drill holes were put down to the Trinidad sandstone which underlies the coal measures in this field. These drill holes in general, showed very satisfactory results. Two workable coal seams were penetrated by most of these drill holes, the upper seam being six and one half feet thick and the lower seam having a thickness of ten and one-half feet. The two seams are separated by forty feet of sandstone and shale. Analyses of the seams proved each to be of a very high grade bituminous coal possessing hardness much above other bituminous coals, and having very bright lustrous appearance. Tests of more than a year's duration proved the coal to store excellently in closed bins and also in open bins where coal is exposed to elements. The drill hole data further showed the coal seams to pitch more than fifty per cent or about twenty-six and one-half degrees. The pitch direction being approximately South 65 degrees East. The drill holes further proved the coal seams did not outcrop at any point on the property, and no evidence of coal outcrop has been found in near vicinity. A splitting and pinching out of seams was found to occur some two hundred to three hundred feet of theoretical outcrop at very Western boundary of property. The most Easterly or No. 6 drill hole has a depth of eight hundred fifty feet to floor of lower coal seam. The Trinidad sandstone was found to be immediately under the lower coal seam, and the Pierre shales lying under this sandstone. Plans for Development and Sinking Having obtained sufficient data, plans for development of the property were carefully made sometime in advance of the actual opening of the mine. Every condition was carefully studied and the maximum production of clean and well prepared coal at as low a cost as possible during the entire life of mine was kept uppermost in the minds of all. The life of mine is estimated at approximately fifty years. It was decided to open up the lower and thicker seam first, and due to the pitch and other conditions a slope opening was decided upon for its extraction. The pitch of the coal having been found to be from fifty to sixty per cent or twenty-six to thirty degrees, the plan of driving the slope directly down the pitch of seam was eliminated and a plan that would give a more economical grade was decided upon. To obtain a lesser grade, a point several hundred feet west of-and at a less elevation than the theoretical outcrop of coal seam was selected for the slope opening. (Fig. 18.) To have driven directly down the pitch of coal seam would also have given the slope an uneven grade as the pitch of coal seam varied as it approached the crop. From this point of opening, the slope was to be driven on a thirty-one per cent, or' about seventeen degree pitch to intersect coal seam in No. 6 drill hole, a distance through the Pierre shales and Trinidad sandstone of two thousand five hundred fifty feet, the slope to be driven practically due East

Jan 1, 1925

By J. J. Craron

MR. J. J. CRARON: If Ross Weber rings that bell of his, I think I have a few secrets on him that I will tell. It is not such a long time ago when the sales and executive departments of the coal industry were constantly urging the operating department to increase their output, and this cry for increased production resulted in vast development work and increased capacity to the point where the operating departments are today in position to produce coal upon sudden demand far in excess of the ability of their sales departments to dispose of it. So today our ability to produce coal is away ahead of our ability to market it. There are many reasons, of course, for this condition. First, the present economic situation, which has prevented even a normal consumption of coal. Secondly, the over-development and production of every commodity and industry as the result of war time and post-war time prosperity. Thirdly, the inroads made by competitive fields, particularly oil and gas, because of the desire of the public for automatic heat.

Jan 1, 1934

[Adams, E. R Rock Springs, Wyoming Adams, V. H. 422 East San Miguel Street, Colorado Springs, Colorado Allen, Earl W 257 Rio Grande Street, Salt Lake City, Utah Allen, Louis B . Box 1920, Denver 1. Colorado Allen, Thomas Argonaut Hotel, Denver, Colorado Alston, G. L Mine Safety Appliances Company, Pittsburgh, Pa. Ambler, J. B Box 591, Denver, Colorado Apperson, A. B. 394 Elm Street, Denver 7, Colorado Arnett, L. L. 325 North First West, Price, Utah Audin, Abel Somerset, Colorado Audin, Clement, Jr Paonia, Colorado Audin, Clement, Sr Box 627, Paonia, Colorado Audin, Ralph Box 285, Somerset, Colorado]

Jan 1, 1952

By Glen A. Knox

The writer has been asked to set forth for this Institute, the experience of the past eleven months in the mining operation conducted at Sweetwater Mine in which coal has been produced by the use of Link-Belt Conveyors on long faces. The coal in this mine has an average of six feet three inches in thickness, and lies on an average pitch of five degrees. The roof is a sandy shale of medium hardness and has been generally considered as good top in the room and pillar method of mining. When our company became interested in conveyors, the writer visited most all of the mines in the East where conveyors and other mechanical methods of mining were in use and decided that the modified method of w-hat is in use at the Norton-West Virginia mine would be the most feasible for our conditions. We in- stalled three hundred feet of conveyor as an experiment to see whether or not our roof could be handled and taken care of on long faces. This three hundred feet was installed as two separate conveyors, one as a face conveyor-100 feet in length, the other as a heading conveyor that delivered the coal into the mine car on the main entry. This face was worked directly on .the strike and down the pitch. This did not prove to be a success as the caving of the roof carried over to the working face and necessitated propping between the conveyor and the face and it was also necessary to shovel coal on the conveyor up the pitch. After working out this block, 200 feet in length, we installed these two conveyors at a place adjoining this worked out block, but on a half V shape shown on the sketch. This block of coal was sixty feet wide. This method proved to be very successful. We cut a place, moved the conveyor against the face before shooting and carried two rows of cribs between the conveyor and the cave, and caved the roof every second cut. After working out this block we were satisfied that this system was feasible with our mine. We then ordered twelve hundred feet more of the same type as the trial conveyor with the exception of a very few modifications. We then installed this fifteen hundred foot unit on the four faces shown on the sketch, with one hundred feet to each face, two hundred feet on each heading and three hundred feet on the main conveyor that delivered the coal into the pit cars. We also had a head and rear section for each of the four advancing places shown on the sketch. As the sections were taken out of the heading conveyors they were installed on the advancing conveyors, and when the faces approached the main conveyor, the main conveyor was taken out and installed in the next uphill or main conveyor place. The roof caved very well in line of the points and was broken about every twenty feet. It broke in a straight line and did not curve at each V. We encountered no trouble unless we permitted one of the points to get behind. The maximum tonnage possible to be produced on this method was estimated to be seven hundred and twenty-five tons a day, assuming that all places were cut and cleaned up in one shift, and this we did for several consecutive days. While this was a success from a cost standpoint, we felt that we could

Jan 1, 1925

By F. C. Miller

The Colorado Fuel and Iron Company has divided their coal mines into groups or divisions: Las Animas, Huerfano, Fremont and Gunnison counties. Each division is represented by a safety committee composed of three men appointed by the management and three men selected by the employes? representatives. The three men appointed by the management are usually from a group engaged in routine work that is primarily of a safety nature. Mr. Robert McAllister, chief mine inspector; Mr. George B. Parker, superintendent of first aid and mine rescue training; Mr. F. C. Miller, chief chemist, fuel department; and Mr. 0. C. Irwin, assistant chief electrician. The three men appointed by the management act in each of the four divisions. It is the duty of the safety commit- tee to visit each mine three times per year and make a thorough investigation of conditions underground and on top. Their report is in the form of recommendations to the management for their consideration. They are also called to investigate all fatal accidents and learn, if possible, the cause leading up to the accident and recommend precautionary measures that will prevent the recurrence. This committee inspects the haulage roads, air courses, manways, electrical equipment, ventilation, timbering, working places and humidity. In addition, each mine has a local safety committee with the superintendent acting as chairman. It is the duty of this committee to keep in daily touch with conditions underground and on top. They hold weekly meetings and discuss problems related to safety. These men work on local conditions that govern their affairs. As an example: One of the mines has a checking out board at the man-trip parting in addition to the regular checking in and out system as required by law, and this board is checked before the man-trip leaves for the outside, giving the officials a chance to take prompt action in looking up a man who may have become ill or injured. Should a man walk out and forget to check off, there is a penalty imposed. The ventilation of a coal mine is most important and the method of conducting the air to the working face is one of the greatest precautionary measures linked with safety. A quantity of air must be maintained at every working face to insure rapid diffusion of explosive or noxious gases and in a manner without interruption. With this intent in, view, the Colorado Fuel and Iron Company is installing fan equipments with capacities of 200,000 cubic feet per minute with dual drives, twin fans in some instances, for insured circulation. Dual drives consist of a steam engine using exhaust

Jan 1, 1925

By J. J. Wilson

To explain in detail the manufacture of seamless pipe and tubes is something I venture to say that has never been done to a point entirely satisfactory. The manufacture of seamless tubes dates back to 1885, when Mannesmann Brothers invented the roll-piercing mill. Ten years later R. C. Stiefel invented the disc-piercer, which first came into general use in this country. At the present time the Mannesmann roll and the Stiefel disc-piercers are used, the Mannesmann rolls particularly for the larger size billets. Sizes produced at first were relatively small and the product was cold drawn to provide a smooth surface. The early uses of seamless material were chiefly for mechanical purposes, such as boiler tubes and bicycle tubing, and the latter for some years taking the heaviest tonnage. Improvements in the hot process were gradually made; the early Pilger type rolls were largely superseded by the two-high rolling mill for rolling out the tube after being pierced, the reeling machine for diagonal rolling, the sizing mill for giving exact outside diameter, and finally the sinking mill for reducing larger diameter tubes to smaller diameters.

Jan 1, 1932

By Lyman Fearn

Men and institutions are what they are largely because of inheritance. Out of the past comes experience that enables men to build more wisely than did preceding generations. The field of possibilities has widened as the horizon of men's vision has been extended. The realization of these possibilities has depended largely on the application of men's natural endowments, brain and brawn, to the problems at hand. In the field of mechanized mining, Wyoming has a greater percentage of men with vision, who have a realization of the possibilities of mechanized mining, than any other state in proportion to tonnage production. With the introduction of mechanized mining systems have come problems that have caused the men who are connected with the safety work much thought. Discussions on mechanical drilling, cutting, loading, conveying, haulage, etc., have come in for their share of the debate. There have been a few attempts made to show that mechanical mining is safer than are the more primitive ways of doing underground work by man power. We also have a number of places in the coal producing States of the United States, where the mechanized systems have been abandoned chiefly on account of the safety element involved bringing about condemnation of the system by State inspection forces. Certain types of scraper systems have been condemned, and some have voiced opposition to long faces. This would lead us to believe that the question is still a debatable one as far as the safety element is concerned. It is only fair that we discuss the operations of mechanical systems and from the results obtained take analysis of conditions as they exist, basing our conclusions from the results obtained.

Jan 1, 1928

By N. H. Wetzel

Railroads, attempting to increase their tonnage without adding new lines, have for some time realized there is a definite relationship between increasd haulage efficiency, and constant communication with each moving unit that operates along their roadbeds. Elaborate radio communication equipment has been devised for this purpose, and is rapidly being installed. Coal mines are faced with similar haulage problems and have sought this constant contact through the use of telephone systems, and dispatcher stations. Often the fixed mine telephone system is unsatisfactory, since the desired person is not present at the phone when needed. Dispatchers lose contact with a motorman as soon as he is out of sight, until he calls in from another telephone. The recently developed frequency-modelated radio phone which makes use of the trolleywire network in a mine as a carrying medium, permits instant and continuous contact between dispatcher and locomotives. The motorman can immediately contact another motor or the dispatcher regardless, of his motor's position on the trollywire system, whether moving or standing.

Jan 1, 1948

By James F. Howe

Modern civilization is centered around a small group of essential occupations, the three principal ones which are agriculture, mining and manufacturing. Agriculture might be called the most important of the three, as it has to do directly with the supply of food for the human race. Mining, however, is certainly next in importance, as it furnishes the supply of fuel and many of the raw materials used in manufacturing. Without mining, modern machinery and many industrial operations would be impossible. Mining takes advantage of the, natural resources in fuel and minerals that lie underneath the surface of mother earth, and while at times some of these metals are hard to find and mines come and go, mining must continue to increase. Mining is no longer a haphazard proposition but one calling for careful study and complete plans of operation for years to come. The shafts, power houses, rock dump crusher, concentrator, and other machinery must be located advantageously in order to enable owners to make a profit. Many tons of rock or mineral must be mined frequently to get one ton of concentrated metallic ore or metal itself. Economy in mining is just as essential as it is in manufacturing. The mining engineer of today is called upon to utilize every branch of engineering, and not only, is a wide: range of knowledge required, but ingenuity to meet the unusual conditions which are constantly arising from week to week. On account of the wide variety of information required by the mining engineer, some things with which he is in almost daily contact may be passed over with only a small amount of attention, provided everything is going well, in order that time and attention may be focused on what might be termed the more important features of mining operations. Because competition has become keener than ever, owing to overproduction at times of certain minerals, it becomes a matter of first, importance to understand as far as possible the factors which enter into the cost of production of any mineral which may be mined. In such times of overproduction, the high cost mine is forced to close down while the low cost mine may, if desired, be kept running constantly. In keeping a cost record, wire rope on account of its high first cost 19 coming into the lime light, and a comparison of records of one mine with another is now frequently made in order to see whether the rope service is satisfactory or not. Every rope maker, on the other hand, is interested in seeing that the rope which he produces gives the maximum possible return for the money invested. Modern mining owes much of its success to the use of wire rope for hoisting materials from beneath the surface of the ground. Deep mining would be impossible without the use of wire rope as a means of hoisting. A study, therefore, of rope problems in mining work and a discussion of the points which are beneficial to maximum life will enable the mining engineer, manager, or superintendent to keep his costs down to the minimum while at the same time he provides a suitable and sufficient safety factor for operations at all times. Mining might be defined as the extraction of coal, metallic ores, or minerals from below the surface of the ground. This definition does not cover what is known as, open pit operations or quarrying but covers the

Jan 1, 1922

By J. J. Welch

The thought and practices in the field of accounting in the past two or three years are undergoing far-reaching changes, but more important than this is the changing viewpoint of business managers toward accounting reports and statistics. Accounting is no longer considered a necessary burden of business, for progressive managers and operating officials everywhere look upon it as a service. A service of supplying operating men and executives with information on their affairs which enables closer and more effective supervision, to the end that business may be conducted more satisfactorily and more profitably. This service is the real function of accounting in business management. Of the many treatises on accounting published in recent years, the great majority deal with principles and procedures, and were written purely from the accountant's point of view, thus they appeal, and are of interest, chiefly to accountants. Recently, however, the interest displayed by the operating man, be he president, general manager, superintendent, mine foreman or potential mine executive, calls upon the accounting department to serve him in furnishing him with figures showing the financial position and economic progress daily. In order to effectively render this service the necessary co-operation between management, operating and accounting -forces must exist. Satisfactory services may be developed only on a basis of close contact and pulling together between these departments. It is not a one-man job, the responsibilities necessarily rest on all. This co-operation contemplates:

Jan 1, 1932

By M .. K. Stewart

(Here follows descriptive movie.) CHAIRMAN KNOX: Thank you very much, Mr. Stewart, for this wonderful paper and picture. We are indebted to you. It certainly is the most interesting thing I have ever seen in connection with wire rope, except paying for it. I think there are a lot of questions that could be asked to bring out some points that we are not generally understanding of. Are there any questions at this time? I know Mr. Stewart will be glad to answer them. Come up to the front, Mr. Stewart. MR. STEWART: That's all right, thanks. CHAIRMAN KNOX: If there are any questions, let us have them. (No response.) Well, we will pass on to the next paper. CHAIRMAN KNOX: Our next paper will be "Self-Preservation, with Some Comments on Mechanical Loading," by Benedict Shubart and Charles Schloss.

Jan 1, 1935

By John M. Jennings

The Hiawatha pitmouth is located at the head of the middle fork of Miller creek, at an altitude of approximately 8,100 feet. The coal is lowered to the tipple down a gravity tram two miles long, in 16 car trips which carry about 60 tons net. The average running time of the trip is about nine minutes. At the bottom of the tram there are two tracks for the loads and two for the empties. The trip, after being cut off the rope, is dropped by gravity onto a feeder, where the cars are uncoupled and fed one at a. time across the pitcar scales and into the dump. The dump is of the full revolution type, friction driven. On passing out of the dump the cars are returned by a kickback onto the empty car haul. They are caught at the bottom by a brake which consists of a pair of steel squeeze blocks operated by heavy springs. The empties are elevated to the double tracks, where the trips are made up. The feeder, scales, dump and empty car haul are all built on the solid ground of the hillside instead of being incorporated in one structure with the screening plant. The coal is dumped into a small hopper with a capacity of about 15 tons, whence it is fed by a reciprocating feeder onto a scraper conveyor which takes the coal over to the screening plant, a distance of 120 feet. This conveyor is 48 inches wide and travels at 120 feet per minute. The screen itself is interesting. It is of the Marcus Horizontal type.

Jan 1, 1925

By Edward Bottomley

Mr. Chairman and Gentlemen: I tried to get Benedict Shubart to have some fellow-some big fellow with a big voice-to read this paper for me, but he said there was nothing doing; [ ] that I would have to read it myself. I will try and not take up too much of your time. It is a pretty big subject, Mechanical Loading, and it covers a good deal of ground. I have merely touched on the high spots, as it were. A great deal has been preached and written in the last year or so about mechanical loading, and I doubt if any other subject in the mining industry has been discussed so freely and as often in the last few years. It is not the intent of this paper to dwell on the merits or demerits of any [ ] particular type of loader, that is, to say what the writer thinks is the most efficient or most inefficient machine. There are several types of loaders on the market to-day that are proving very successful in many mining districts. Some of these, five or six years ago, seemed to be a miserable failure from every standpoint, mechanically

Jan 1, 1926

Jan 1, 1931

By D. Harrington

E. H. DENNY (United States Bureau of Mines, Denver, Colorado) In the absence of Mr. Harrington it is my privilege to read his paper, which is in his usual, forcible and sincere style, and it is within the province of this Institute, certainly, to go into it as it concerns safety and efficiency in mining. He brings out some points in his paper that, I think, are well worth the consideration of the Institute. The figures he uses were compiled by Mr. Adams, of the Bureau, and cover a five-year period. However, examination of similar Bureau figures for a ten-year period, or any other long period on other bases brings out similar results. The figures in this paper have been based on the million hours of exposure of accidents, and the figures based on three hundred working-man-day basis, or on tonnage, brings out similar results. This paper is entitled "Accident Record in Western Mines," and it is, in a way, an amplification of Mr. Harrington's letter which was read at the Glenwood Springs Meeting.

Jan 1, 1927

By J. H. Emrick

When I was asked to read a paper to you, I wondered what idea I could bring before you which would be interesting and which would be helpful in your work in operating coal mines. The Institute has been studying ways and means of increasing the safety and efficiency of mine operations. Almost every subject along this line has been discussed from time to time. In thinking the matter over it occurred to me that there was one thing used by practically all coal mining companies in considerably large quantities and which in many cases does not receive the attention it should. It is the cutter bit placed in the cutter chains on coal mining machines. Coal mining machines have been repeatedly improved during the last twenty-five years until their efficiency and convenience have reached a high level. The generating units making electrical power to operate them also have been developed to a similar degree. This machinery has been in- stalled at a great expense to coal mining companies and the installation made for the sole purpose of pulling coal cutter bits through coal. Why not then give these cutter bits some attention so as to see that they do their work as efficiently as their driving and propelling units? The consideration of this question easily divides itself into three principal parts-First, the kina of steel out of which to make the bit; Second, the proper form or shape to give it; and Third, the tempering of the bit. Let us discuss them in that order. There have been tried at different times' various grades of steel for cutter bit uses. The cheaper steels, having a very low carbon content (.10 to .30 per cent carbon) have proved un- satisfactory because such steel cannot be tempered so as to produce a satisfactory cutting tool. Because of the low carbon content, it cannot be hardened to retain its cutting edge. It dulls quickly, bends easily on striking any hard obstruction in the coal, and so requires constant resetting to its original form. The high priced alloy steels when properly shaped and tempered will give a bit that would make a clean, even cut in the coal if no impurities were encountered. Such a condition is rarely found. Alloy steel is quite brittle and on striking impurities, such as sulphur balls or a sand spar, is readily broken and so the loss of material through these broken bits and the high price paid for it more than offset all the other advantages which this steel has shown in cutting. Experience has shown that steel having approximately .70 per cent carbon and from .25 to .35 per cent manganese will give the most economical results. Some mines have obtained better results by using a steel of slightly higher carbon content and in some cases a grade of tool steel has been used. The disadvantage of using a steel having too much carbon is that it can easily be spoiled in the black- smith shop by overheating. Steels having a carbon content of about .70 per cent have a sufficiently wide range of temperatures at which they can be forged and hardened so that with ordinary care and attention they are not likely to be burned. Steel of this quality, therefore, has been found to be the most practicable because of its reasonable cost, ease in working and tempering and general durability. In the early days of mining machines, comparatively few bits were used because each machine required but a few bits because there were but

Jan 1, 1925

PRESIDENT BOTTOMLEY: Gentlemen, the next order of business, if you wish to discuss it is Mechanical Loading. We still have a little time left that could be devoted to that subject, and the meeting will be open now for that purpose. Where is Mr. Edge- worth? J. E. EDGEWORTH (Foreman, Union Pacific Coal Company, Rock Springs, Wyoming): Here. PRESIDENT BOTTOMLEY: Yon start the ball rolling. Tell us what you are doing in the Rock Springs District, on the mechanical loading. SECRETARY SHURART Mr. Edgeworth is the man at the face handling the coal. He never sees the light of day these late winter mornings.

Jan 1, 1927