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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

The Morning Session of the Forty-Eighth Meeting of the Rocky Mountain Coal Mining Institute convened in the Little Theater of the Broadmoor Hotel, Colorado Springs, Colorado, at 9:30 a.m., June 4, 1952, Albert M. Keenan, Chairman, presiding. CHAIRMAN KEENAN: Ladies and Gentlemen, here we have our third and final clay of our program, and I wish to take this opportunity to thank all of you for your attendance, both in the past meetings and this one this morning... I am particularly delighted to see that we are all here this morning after the very enjoyable banquet last night. It is a little difficult to get people gathered up after such an occasion.

Jan 1, 1952

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 Warren C. Bracewell

At your request, am submitting to you several suggestions for the amendment of our safety code which you felt should be kept up to date. These suggestions are the individual opinions of the several members of the Committee who have expressed (heir wishes to me in the form of letters. I am particularly indebted to Mr. Daniel Harrington, Mr. Wm. Littlejohn, Mr. Warren Bracewell, Mr. James Dalrymple and Mr. Hugh McLeod. Would recommend the following amendments Section 1. Wherever practical trolley wires should be securely hung to roof or timbers at a distance of not less than five feet and not more than six and one-half feet above rail and six inches to one side. Spacing of hangers should be from 20 to 25 feet apart. (Adopted.) Section 2. 500 volts D. C. should not be allowed in any installations. Trolley wires should not carry a voltage of more than 250 D. C. nominal voltage. (Referred back.) Pumps, mining machines and other small machinery units where A. C. power is used should not carry a voltage of more than 220. Large units, such as pumps, motor generator sets and hoists, may use a volt- age of 2,200. When power cables to operate same are of armored construction, cables should be securely buried at all crossings, on haulage-ways or where men travel. (Adopted.) Section. 4. Where power lines pass through door frames or stop- pings they should be properly insulated with porcelain compound or rubber tubing. Wherever men get on or off man-trips in vicinity of trolley wires same should be secure1y guarded and should also be protected with a cut- out switch, same to be pulled before men are allowed to get on or off trips. (Adopted.)

Jan 1, 1926

By David Scrymgeour

All low cost coal has been mined. Engineers are searching for a safe and effective way to mine coal seams' deep within the earth. The most modern of these is the RL, an acronym for Robotic Labor. Mining robots are programmed to do specific jobs but can think on their own during an emergency. MR's, or mining robots, usually have a same basic shape. A torso is mounted on treads. Designers chose treads because it gives the robot a great deal of mobility. The torso has two arms. One arm is equipped with a human hand. The other has a human-like hand. Mining is done underground. A small robot goes around punching holes in the coal. A small charge is inserted in the hole. The MR ignites the charge with his laser. It explodes after three minutes. The MR returns to the station where his battery is recharged. Mobile cement barricades are moved between the blasting area and other working MR's. After the charge explodes the barricades are moved to another area. The MR returns and cuts the coal chunks into pieces. Another robot comes and loads the coal and carries it to the loading bin. From there it is taken to the surface where it is weighed and shipped. The whole process was done by robots. Humans just supervise but help in an emergency or malfunction.

Jan 1, 1987

By Joseph Harrington

It is sufficiently correct to say that domestic solid fuel is universally hand fired and it is almost as correct to state that a very large proportion of hand-fired domestic fires are extremely inefficient and smoky. This is particularly true with raw bituminous coal for the fuel. The smokeless and efficient firing of domestic coal affords one of the most difficult problems confronting the combustion engineer. This is due to the universally constricted combustion space in the domestic furnace, the complete ignorance regarding the laws of combustion on the part of the average person, and the fact that the laws of efficient combustion are almost completely nullified under these conditions. It is well to familiarize ones self with these laws. These are: 1. The gradual introduction of the fuel to the furnace. 2. The admission and mixing of the right quantity of air with the coal gases. 3. A temperature high enough to permit complete combustion, and 4. A furnace space of volume sufficient to permit of the combustion gases and the oxygen getting together within the confines of the furnace. Even a casual inspection of the domestic heater will show that none of these essential things are present in proper degree, and this is the reason why the problem of domestic firing presents such difficulties. I have analyzed these conditions in a paper published by the Black Diamond, and which has already had wide distribution, so that I will not repeat the rather lengthy discussion in this paper. A survey of the entire field indicates very clearly that a reversal of existing methods and equipment must be had before any real improvement can be expected. It is my firm belief that in this instance above all others it is necessary to build the efficiency and smokelessness into the equipment in such a manner that its performance will be entirely independent of both skill and interest on the part of the operative. To attempt to educate every man, woman and child who periodically throws coal into a domestic furnace would be literally impossible. Much can be done, however, if we could teach the householder the simple essentials of alternate firing, which I have explained at length in the above mentioned paper. This would go a long way toward making the domestic furnace problem more satisfactory, as well as efficient and smokeless. Many will argue, and with good reason, that the domestic fuel should be prepared coke and with this I agree up to the limit imposed by the practical considerations of quantity production, price and the possibility of marketing the by-products. It will be obvious that if enough raw coal should be processed to provide all of the required domestic fuel that the amount of by-products recovered during the coking process would be so great that there would be little or no market at any price which would justify the manufacture of coke. If the by-products were wasted they would not only be a tremendous economic loss, but the price charged for the coke would probably be so high that the market would be limited, and this would defeat the very idea of the whole thing. Much can be done, however, in advancing the use of coke, but I believe that much more extensive and careful experimentization should be had in order to determine the right size and quality of coke for the various domestic furnaces. If coke were to be developed for extensive domestic consumption it is more than probable that the coking process should and could be stopped at a point where the volatile content of the coke would be sufficiently high to permit of prompt ignition and combustion in low draft installations. If the volatile content were from five to ten per cent a very different kind of coke would be produced from that which is now produced with perhaps one per cent of volatile. A skillful manipulation of this feature would make coke adaptable and satis-

Jan 1, 1925

By T. H. Butler

February 22nd, 1926. Mr. Benedict Shubart, 521 Boston Building, Denver, Colorado. Dear Mr. Shubart: At your request, am submitting to you several suggestions for the amendment of our safety code which you felt should be kept up to date. As before, am advising you that these suggestions do not have the approval of the entire Safety Committee, but rather are the individual opinions of several members who have expressed their wishes in the form of letters to me. I am particularly indebted to Mr. Dan Harrington and Mr. Wm. Littlejohn for their assistance. Would recommend the following amendment a to the various sections. Section 1. Wherever possible trolley wires should be securely hung to roof or timbers at a distance of not less than five feet and not more than six and one-half feet above rail and six inches to one side. Spacing of hangers should be from 20 to 25 feet apart. Section 2. 500 volts D. C. should not be allowed in any installations. Trolley wires should not carry a voltage of more than 250 D. C. Pumps, mining machines and other small machinery units where A. C. power is used should not carry a voltage of more than 220. Large units, such as pumps, motor genera- tor set and hoists, may use a voltage of 2,200. When power cables to operate same are of armored construction, cables should be securely buried at all crossings. Section 4. Where power lines pass through door frames or stoppings they should be properly insulated with porcelain or rubber tubing. Whenever men get on or off man-trips in vicinity of trolley wires same

Jan 1, 1926

By R. S. Morton

MR. CHAIRMAN AND GENTLEMEN: To be invited to address the members of The Rocky Mountain Coal Mining Institute on a particular subject is an honor I sincerely appreciate. The subject of this paper is, ?The Advantages of Having Such Men as the Fireboss Under State, Rather Than Corporation Jurisdiction." On the fireboss, primarily, depends the safety of the mine. When all the rest of the mine workers are still comfortably sleeping in the wee small hours of the morning the fireboss steals noiselessly away, from his bed to take up his daily task, a tour of inspection. He enters the mine, he inspects alone they workings that will be filled with men whose safety is in his keeping. Loyal to his fellow men and responsibilities of his position; he seeks for danger in every place, on every road and travelingway; going over caves, through dangerous places where none of the others are expected or allowed to go alone. How many of us give a thought to these dangers and the faithful work that this guardian performs for our safety. After the fireboss has made this round of inspection, he reports all the dangerous places to the foreman and enters them in the book; he is supposed to have performed his duties; he has no authority to enforce his recommendations. He has found a number of rooms that have not been timebered as they should be for the safety of the digger; he has told the diggers to they timber, up better for their own safety; he has kicked to the foreman about these same places. These conditions. continue until there is an accident. The fireboss reports, broken crossbars or bad roof on a roadway or some other danger to the foreman, but the foreman does not have it fixed, making, excuses, as he cannot put any one on that work today; or that it will stand until some idle day, and that is the way things go until the fireboss gets so he wonders what good he really is, is it any wonder it is hard to get good men to take this position of fireboss? The remainder of the shift the fireboss is used as a general roust-about, having to do such, work as building stoppings, help the timberman or track layers, pull rails out of danger in pillars, a trapper is off and he is told to trap that day, when the mine is idle he is laid off to cut expenses. That is the way the fireboss is treated. The fireboss is not merely a merely a necessity to be lightly regarded but a factor whose authority should be unquestioned. The fireboss has made his district and knows just what conditions the workings are in, and sees lots of dangers that the foreman does not. In the morn-

Jan 1, 1921

By D. J. Griffiths

Beyond doubt it is practically impossible to eliminate all chances of accidents from falls. Mother Earth is not going to give up her treasures without some sacrificing on our part. This particular question ranks among the important subjects connected with coal-mining, and has been given less attention as a factor of life- and limb-destroyer than any other cause. The single fatalities which happen create very little attention; nevertheless, when counted up at the end of the year, they outnumber the unfortunate ones that are mowed down by the wholesale by mine explosions. Fire-damp and coal dust were often considered the greatest evils in coal-mining. All records, however, prove this conclusion to be wrong. The second annual report of the Bureau of Mines gives the loss of life caused by falls of coal and roof in 1910 as 1,310, and in 1911 as 1,321. The reports of Pennsylvania mine inspectors for a period of thirty-three years show that 59.38 per cent of all the accidents underground were caused by falls of roof and coal. Also, the Bureau of Mines shows in its last issue on fatalities that accidents from fall of roof and coal killed more men than any other two causes combined, and that they account for more than half of the deaths under- ground. It seems we are getting too accustomed, taking too many things for granted, running too many risks, trusting too much for the best, and preparing too little for the worst. We must remove the cause; then the effects will cease. However, I can see that a better day is here. The main damaging factors underground are falls of roof and sides. A bad roof is tender and lacks the adhesive qualities to sustain its own weight over comparatively small areas. A roof of any character which is frequently penetrated by well-defined slips and cleats, is characterized as a treacherous roof. The carelessness of men has been one of the main causes of most of the accidents in mining as well as in any other industries. Three Grades of Miners Miners can be classified into three distinct grades, to-wit: the experienced and careful, the experienced and reckless, and the inexperienced. The accidents which the first class usually meet with occur through the carelessness of their co-workers, as well as through accidents which are termed unforeseen, such as falling roof between timbers, and between the timbers and the face of the coal. This may have 'previously given evidence of being absolutely sound and safe, but be released by invisible slips or by sudden outburst of occluded gases in large quantities, as we term big blowers or feeders,

Jan 1, 1913

By Kirk Nobis

Develop a Risk Management Plan for Your Mine ? Why? ? Measuring ? Managing ? Conclusion

Jan 1, 2006

PRESIDENT LITTLEJOHN: Gentlemen, you have heard Mr. Dyer's paper. The meeting is now open for discussion. MR. NORMAN: I would like to ask the gentleman what is the distance between your crosscuts for the ventilation of rooms and entries in the state of Utah?

Jan 1, 1925

(The following discussion took place on this screen lecture in the dark.) MR. SHUBART: Would you give us a little .explanation as to the operation of this machine and what you are doing with it? MR. TESCHER: There is a 20- horsepower motor, rheostat, crusher, and a fan mounted on one base plate and operating on one shaft. The fan is overhung on the shaft. The only bearings you have are the bearings on each side of the crusher and the motor hearings. On one side of the ma- chine there is an opening for feeding shale. The machine is operated at 1,200 revolution per minute and as the shale is pulverized, the fan automatically exhausts fine dust from the crusher from an opening in the top of the crusher. The machine pulverizes 3,000 pounds in eight hours, reducing the materid to one hundred mesh. The last ma- chine we put in has been operating continuously fifteen hours a day for the past sixty days, without repairs of any kind. PRESIDENT LITTLEJOHN: Where is the machine in operation? MR. TESCHER. At the Royal mine. We have used ordinary mining ma- chine cable in local movements of the machines. This has enabled us to have twenty-two locations throughout the mines. The mine is highly gaesous, and the machines had to be placed on intake air. MR. SHUBSRT: What type of crusher do you use? MR. TESCHER. A No. 16 Universal, operating at 1,200 revolution per minute. M. SHURART: What material do you feed to it? MR. TESCHER: We have shale three-quarters of a mile from the mine. In the winter months we have been troubled with moisture. We build a kiln and get this shale and load it into the kiln for drying and then place it into a pit car and take it into the mine. The material must be dry. We have also used slate in the mine and have had good success. The slate at the mine is fairly hard. I presume, however, that the slate will probably carry a high silica content. MR. SHUBART: Mr. Harrington claims that silica does not do the harm, as was formerly supposed. MR. TESCHER: There is still a question as to whether it is harmful or not. PRESIDENT LITTLEJOHN: Are there any of these machines in operation closer than Aguilar? MR. TESCHER: There is one at the Alamo mine. Mr. Quealy also purchased a couple of them for use at his Wyoming mines. PRESIDENT LITTLEJOHN: Are there any other questions you would like to ask Mr. Tescher regarding his rock dusting machine while it is on the table for discussion? MR. DALRYMPLE, SR.: How many men does it take to operate it? MR. TESCHER: One man operates the machine. Sometimes we put the

Jan 1, 1925

By Parley Potter

GENTLEMEN OF THE COAL MINTING INSTITUTE: I was requested to write an article on mining a short time ago; however, the time has been so short that I have not had time to prepare an article as I would like to have presented it to this body. In writing this article it has not been my intention in making comparison of various mines, to favor one or discredit the other. I hope it will be considered in that light. The coal mining industry as I have seen it in the past, at present and in the future. In years gone by large tracts of coal land could be obtained at a very small cost, and as yet coal land may be purchased at a reasonable price in this country, but I believe the time is near at hand when the methods of mining will have to be changed greatly in this country. Many changes have taken place-in the last few years, some of them have been forced by law, others by the coal operators themselves, after being convinced that the changes made were for their own benefit. During my 20 years in the mines I have seen thousands and thousands of tons of coal lost that could have been saved if proper methods of mining had been used. The Room and Pillar system of mining coal is none. too good at its best ; a certain per cent of the coal is always lost, yet it is about the only system that can be used under certain conditions, but where the Longwall system can be used I believe it is the best system yet introduced. If the Longwall system is used' there is no coal lost. You get it all as you advance with the workings. Some coal operators object to the Longwall system for several reasons, and most of the reasons they advance are not founded on facts. For instance some of them claim it is too expensive. I will admit that the cost per ton is a little higher in Longwall than it is in Room and Pillar as a rule for the amount of coal' mined, but after the Room and Pillar mine is finished as a rule there are thousands of tons of good coal lost, for the simple reason that it cannot be mined at a profit. In many cases if the same mine had been operated on the Longwall system every ton of saleable coal could have been mined at a fair profit, and in the long run would have netted the owner much more money than it did under the Room and Pillar system. The Longwall system has been in operation many years in Europe and especially Great Britain, and is the most approved of systems in many countries at the present time. Millions of tons of coal have been saved by its use in those countries. It is claimed that the Armour Packing Company loses nothing but the squeal of the hog when it is killed, and doesn't allow it to squeal much. Why lose coal if the Longwall system of mining will save it? The Longwall mine is far more easy to ventilate than the Room and Pillar mine; the air has a much less distance to travel for the same amount of working face in Longwall than it has in the Room and Pillar.

Jan 1, 1921

By J. J. Forbes

Gentlemen : It is a pleasure to come to Glen- wood Springs to participate in this meeting of the Rocky Mountain Coal Mining Institute an organization created to handle chiefly the economic questions dealing with the coal industry of the Rocky Mountain District. I am not unmindful of the many and varied problems confronting the mining industry of this country which is so general at the present time throughout the United States. By reason of the difficulties experienced in marketing the product of your mines, there is all the more reason for greater economy and efficiency in production. No industry can be efficiently operated without giving due consideration to the safety of the employees. Safety and efficiency are inseparable for the success of any industrial enterprise. While the Bituminous coal companies of the United States are doing splendid work in the promotion of safety, yet our fatality rate is exceedingly higher compared with that of foreign countries, and with greater cooperative organized effort on the part of mine owners, mine officials, mine workers, and state and federal governmental agencies having jurisdiction, much more substantial progress can be made in the future and a greater economic saving .to the industry effected, not taking into consideration the greatest and most important phase of safety, which is the conservation of life and health of all those who are engaged in the occupation of mining. You are concerned with freight rates, marketing of coal and similar operating problems. Yet have you earnestly considered the vital question that plays so important a part toward the success of any mill-

Jan 1, 1926

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

The session opened at 9:00 a.m. Presiding- Herman E. Knight, Vice President, The Pittsburg & Midway Coal Mining Co. and Gulf Mineral Resources Co., Denver, Colorado. The first speaker was Dale A. Eastman, President, Eastman, Griggs & Associates, Salt Lake City, Utah. Subject-"Professional Staffing for Mining Operations." Mr. Eastman received his Business Degree from Shadran State College in 1971. He was Head Coach in basketball and football in Lyman, Wyoming, prior to joining Bectel. With Bectel five years in training, development and staffing. Was Director of Construction Administration for Southwest, United States, Bectel Power Division prior to entering the Executive Search Division. Currently President, Eastman, Griggs & Associates and also Vice President of E&B Investments and Managing General Partner Duffers Ltd. (See Index for printed text of Mr. Eastman's paper.) Mr. George J. Miller, Attorney, Dechert Price & Rhoads, Denver, Colorado, was the second speaker. Subject-"Rail Transportation After Staggers Act."

Jan 1, 1981

PRESIDENT LITTLEJOHN: I have every reason to know Mr. Pryde was carrying out some experiment a while ago in some of his mines. He and I had a little correspondence on the question, and I think he may have a word or two to say about it. He has not been on his feet today at all. I will ask Mr. Pryde to tell us what he has to say. MR. PRYDE: I have not very much to say about shooting coal with permissible powder as far as slack is concerned because we are not in the commercial business. All of our coal goes to the railroad and a very large part of it is crushed for use in the stokers of the locomotives. We are on a 100 per cent permissible powder basis and as far as I am able to see, I do not believe that the percentage of slack is increasing with its use. We find it hard to convince our commercial neighbors of this fact because they are naturally very much against increasing their percentage of slack on ac- count of the low price received for this grade of coal. I, personally, believe that where a change is made from black powder to permissible powder the percentage of slack will be increased for a time because the miners have been accustomed to using black powder and they are rather suspicious about going to the permissible powder and I do not believe that we can blame them very much. So the tendency with them is to use too much powder. We have gradually overcome this, although, as I said before, we have not kept close track of the production of slack. However, we try to get as large an amount of lump coal as possible. Broadly speaking, I can say from observation that in my opinion there is very little difference in the percentage of slack with the use of the permissible powder that we have today than there was with the use of black powder. I also get this information from our mine superintendents. Mr. Peterson and the other explosive men have been very helpful to us in the use of permissible powder and I confess I have to take everything back that I said several years ago. At that time I was against permissible powder, particularly on account of the cost, but, with the newer permissible powder, we have gotten the cost down very well. I know today that the cost of permissible powder in the coal mines of the Union Pacific Coal Company is less than when we were using black powder. I know this because of the fact that we kept a record of the number of tons we got with black powder, and the number of tons we get with permissible powder compares very favorably in cost. I know this, too, because of the fact that our employes, except in the first few weeks of using permissible powder, have made no demand upon us for any in- crease ill pay to offset any added cost that might accrue in the use of permissible powder and the fact that they have asked for no increase is very conclusive proof to me that it is not

Jan 1, 1925

By H. Petersen

If a coal mine producing two hundred thousand (200,000) tons of coal per year could effect a 2 per cent decrease in the percentage of slack there would be an additional 4,000 tons of prepared coal produced. Most operators will say that these prepared sizes of coal are worth about $3.00 more per ton to them than the slack or in other words an additional $12,000.00 pier year profit could be made by a decrease of 2 per cent in slack. A large tipple with all the finest modern equipment of shaker screens, conveyors, box car loaders, etc., can only produce a grade of coal dependent upon the coal delivered by the mine car at the top of the tipple. In the mine, coal-cutting machines have been doing their part for many years toward decreasing the percentage of slack. There is therefore, only one phase of production left where real effective work can be done, that is, intelligent and constant supervision of preparatory work and shooting. The quality of coal is really entirely dependent upon the kind of coal produced at the face in the mine. Our problem is therefore, at that place. The writer is thoroughly convinced that with the proper placing of holes the use of correct amount of a suitable explosive, thoroughly tamped, with the bug dust entirely removed from the mining, a decrease in slack can be effected. We will take up this problem under five headings. First-The proper placing of bore holes. Second-The proper amount of permissible powder. Third-The proper loading and stemming of the shot.-Cushing shooting. Fourth-The necessity of removing the bug dust from the mining. Fifth - The - standardization of rounds. First-The Proper Placing of Bore Holes. The most important thing and the real secret of successful blasting of coal is the proper placing of the bore hole. This results in the correct balancing of the shot and the securing of the maximum efficiency of the explo¬sive. If you are operating a mine with a 6-foot coal seam, you most likely are using a 6-foot cutter bar on the coal cutting machines. You should use three holes to properly bring down the coal. (1) A center shot in the middle of the room drilled flat, or rather parallel to the mining-the heights of this hole will depend upon the top parting. If the coal is frozen to the roof, it will be necessary to have the hole as close to the roof as possible. If there is a free parting, the hole may be placed lower but not over twelve inches from the roof. (2)

Jan 1, 1925

MR. C. M. GODDARD: Mr. Poli invented this little safety switch box. This junction box he has does improve the appearance mentioned in the underground junction boxes used in the foreign countries, where this thing is compulsory. There was some arrangement whereby the attachment could not be made with the switch in. The switch has got to be out of place before they can put the terminals into this box, which avoids all possibilities of short-circuits, except where protected on the inside of this box. In mines that are not gaseous, this is not so essential, but he has invented a very small junction box which probably. could be built for six or eight or ten dollars; if those things are necessary, for the handling of mining machines and their apparatus, takes current off the transmission line, and he has something that would meet that requirement, and I think when it is looked into it will meet the approval of the Bureau of Mines. He had this little box yesterday, and some of the members had looked it over and think, if they will look more favorably into it, they will find something to their advantage. PRESIDENT PRYDE: I think it is a good idea to bring in safety appliances and devices at this meeting. There were two more devices brought in here this morning; one a safety powder flask, and the other a carbide can. We have talked a great deal about permissible powder. It is going to take a little time to change over, and we would have to use the black powder cans. I will leave them in the window, if you care to investigate them.

Jan 1, 1924