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Frank 11. Probert, Neudorf, Anhalt, Germany (communication to the Secretary): I have read with much pleasure Mr. Collier's valuable paper. But the system of timbering which he describes as used in the levels, stopes, etc., though it must be admitted to be very strong and safe, seems to me somewhat extravagant. The amount of timber required every month for such a system must be enormous; and only where suitable material could be cheaply obtained would such a plan be economically practicable. The first point which strikes me is the unusually great diameter of the timber employed. In the mines of Pfaffenberg and Meiseberg, which are under my supervision, the country-rock consists of argillaceous slates, traversed by innumerable small fissures or joints, dipping at all angles and striking to all points of the compass. Undoubtedly, this net-work has been caused by the upheaval of granite masses in the vicinity. Each fissure is accompanied by a more or less well-c1efinc.d gouge or fluccan, caused by the rubbing together of the slates at or after the original disturbance. In such

Jan 1, 1900

By Thomas D. E.

Discussion at the Manchester Geological and Mining Society' general meeting held in Manchester, March 14th , 1916, with Leonard R. Fletcher, President, in the Chair, of a paper published in Trans. Instn. Min. Engrs., 1916, vol. L., page 482, comprised the author's written response to suggestions made in previous discussion

Dec 1, 1916

John Birkinbine, Philadelphia, Pa.: We have in the Institute two Dudleys—Dr. Charles B. Dudley, who has so thoroughly studied the chemical composition and physical behavior of rail-steel, and Dr. P. H. Dudley, whose investigations and

Jan 1, 1900

Discussion at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 8th April 1916, on the paper published in Trans. I.Min.E., vol.LI, 1916, p.61-71, consisted of a written comment by Wood P.L. that a larger battery would be the only way to secure reliability

Dec 1, 1916

By Hirsch H. H.

Further discussion at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 3rd June 1916, on the paper published in Trans. I.Min.E., vol.LI, 1916, p.61-71, comprised the author's written reply to comments at the April meeting

Dec 1, 1916

Discussion at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 8th April 1916, on the paper published in Trans. I.Min.E., vol.LI, 1916, p.72-90, included written contributions on size and gauge standardisation by Lupton A., Peck W.R., Dean S., Mayer R.W. and Ashworth J., with the author's written response, and by Bulman H.F. and Brown M.

Dec 1, 1916

By Gibson J.

Further discussion at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 3rd June 1916, on the paper published in Trans. I.Min.E., vol.LI, 1916, p.72-84, included a written contribution by Parfitt I.C. and the author's written replies to this and previous discussion

Dec 1, 1916

H. H. Stoek, Scranton, Pa. (communication to the Secretary): Mr. Rothwell's condemnation of my paper on the International Correspondence Schools as not giving an impartial view of the whole field of such enterprises, because it was confined to the description of a single one, might be legitimate if I had undertaken or professed to do anything else than that which I was requested by the Secretary of the Institute to do—namely, to give an account of this particular institution. This is a sufficient answer to all his direct or implied criticisms upon my omission to mention either persons or organizations outside of the special limits set for me. Recognizing fully that personalities have no place whatever in the Transactions, I regret the necessity of making the following statement in answer to Mr. Rothwell's charge that I omitted to give due credit to Mr. Ewald, a former principal of the International Correspondence Schools. The Colliery Engineer School of Mines was started in 1891, and its first student was enrolled October 16, 1891. During the fall of the same year the mine-mechanical course was laid out along the same general line that had already been followed in the mining course. This mine-mechanical course was the foundation from which sprung the later developments of the several mechanical courses. The latest circulars of information of the International Correspondence Schools give the following as their distinctive features: (1) courses of instruction for particular occupations,

Jan 1, 1900

By Mavor S.

Further discussion at the Mining Institute of Scotland's general meeting held in Edinburgh, 12 February 1916, with D.W. Mowat, president, in the chair, of a paper published in Trans. Inst. Min. Engrs., 1915, vol. L, p.625 and discussed vol. L, pp.92, 433, 468, and 704 included comments by Mowat D.W. and the author's reply

Dec 1, 1916

By S a m u e l D e a n

The author's written response to previous discussion was presented at the North of England Institute of Mining and Mechanical Engineers general meeting held in Newcastle-upon-Tyne, 8 April 1916, followed by further comments by Hare S. in support of his view that the conditions in English mines were the reason for less satisfactory results being obtained with heading machines and brief comments by Greener T.Y., President

Dec 1, 1916

By Dean S.

Further discussion at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 12th February 1916, with Mr. T.Y. Greener, President, in the chair, of the paper published in Trans. I.Min.E. vol.L, 1915, p.179 and 388. Written contributions to discussion included Mr. Dean's reply to earlier discussion (p.35-44), further written contributions by Tate S. (p.44-54) and Brown E.O.F. (p.54-56), and oral comments by Hare S., Merivale J.H., Greener T.Y. and Tate S. Particularly debated were the causes of the difference in output between American and British coal miners

Dec 1, 1916

Jan 1, 1900

J. Lainson Wills, Ottawa, Can. (Communication to the Secretary) : The localities of the Quebec and Ontario apatite deposits, and the nature of their occurrence haye been often described in the Transactions and in other publications that are readily available, and I do not, therefore, intend to discuss the many details advanced in Mr. Small's paper beyond the following two points:

Jan 1, 1893

PRESIDENT PRYDE: I think that the overcutting machine undoubtedly presents a great many benefits, especially where the roof is frail. I have found a good substitute for the Arcwall, getting a lighter machine by equipping a machine with a turret truck, you get a much lighter weight, and while the cutter is not movable vertically, you cut not on top of the seam, but about the middle of it. MR. SC'HLOSS: I would like to ask Mr. Pryde the advantages of cut- ting with this turret-mounted Shortwall machine. PRESIDENT PRYDE: It is better for development work in narrow places. In development work you have a lot of narrow places. MR. LITTLEJOHN: Mr. Chairman, we were compelled at Winter- quarters, one time, to introduce them for reason of sand rolls'. We have in that mine a condition-we have sand rolls from twelve inches to two and a half feet, sometimes higher than that-usually twelve inches to two and a half feet, and we had to get some of the C. E. 7's on the turret there and used them for advance work not only in the entries, but in rooms; not only in that particular district, but in fact all the districts in the mine-we have abandoned the power trucks. You can cut without unloading, and that is one of the principal advantages, and when the sand rolls come in it enables you to cut over the top of the sand roll, but the particular objection, we were working a nine-foot wall, and some of the coal was twelve feet thick, so that the miners have raised a little objection to the drilling.

Jan 1, 1924

PRESIDENT MARKS: This is a matter, I think, in which we are all very much interested, and I know We will have considerable discussion on the subject. MR. GIBSON: Wouldn't it be a fact, Mr. Trick, if a mine was laid off on the block system, it would require less ventilation, less cubic feet of air per minute, and therefore you would have that much better ventilation by

Jan 1, 1926

Henry D. Hibbard, High Bridge, N. J. (Communication to the Secretary): There is one chemical factor which has not been considered in the author's tabulation of tests, but which is none the . less important because it cannot be practically estimated, and that is the element oxygen. This element has been, and probably will continue for some time to be, one of the great causes of the continual discrepancies between the chemical and physical properties of steel. Probably oxygen occurs, in important proportions, only in soft steel, such as that which we are now considering. In this steel its physical effect is to diminish tensile strength and elongation. The percentage of oxygen in the steel, under working-conditions that are as uniform as possible, is likely to vary inversely as that of the manganese, or perhaps, and more probably, it may bear even an inverse geometrical ratio to the manganese-content. At all events, to follow the author's plan, the line representing the loss of strength due to oxygen is probably a curve. Plotted by itself, the line would probably be straight; that is, the decrease in strength would be proportional to the increase in oxygen, but if the results were superposed on the percentages of manganese, they would give a curve, because the percentages of oxygen increase faster than those of manganese decrease. Were the oxygen-line to be developed and added to the diagram, it would seem that the manganese-line should then be straight. Due allowance for the effect of oxygen, therefore, would modify two features of the paper. It would increase the figure for the strength of pure iron from 38,000 to about 45;000 pounds per square inch, and it would straighten out the manganese-curve. The manganese-line in the paper is curved between 0.50 and 0.20 per cent. Above 0.50 per cent. it is straight, which may be ascribed

Jan 1, 1893

By N. B. Strydom

I have read with interest all the papers dealing with heat transfer and the setting of heat stress limits that have appeared during the past two decades. Scientifically speaking, most of them can be rated as being of a high standard, and some of them have been acclaimed internationally as masterpieces of logical and calculated reasoning. Weathering of ore minerals A short course on 'The Weathering of Ore Minerals and the Textural Evaluation of Base Metal Gossans' is to be given by Dr I.M. Reynolds in Grahamstown from 4th to 6th October, 1982.

Jan 1, 1982

Operating Characteristics of Centrifugal Fans and Use of Fan Performance Curve Discussion of paper by. Louis W. HUBER, presented at the New York Meeting, 1926, .and issued, as Pamphlet No. 1542-A, with MINING AND METALLURGY, February, 1926. G. BRIGHT, Pittsburgh, Pa.-Apparently from the pressure curves for a forward-curved-blade fan, in Mr. Huber's paper, practically all ventilation-might be stopped with increased resistance. In order, to discuss the characteristics of a fan we need, some better way to measure the characteristics of a mine. You all know that. the average anemometer is not very-reliable. Sometimes two anemometers, supposed to be recently calibrated, will differ 50 per cent. Either this or some other committee should standardize measuring methods. The characteristic curves of fans, given by Mr. Huber, would indicate that the forward-curved-blade fan would cause trouble in attempting parallel operation, because two machines will not parallel unless they have dropping pressure characteristics. On the other hand, it is indicated that with the backward-curved blade, they could easily be paralleled. But few mines use more than one fan. Mr. Huber said that if the resistance of the mine was considerably more than contemplated, the quantity of air might be such that the efficiency of the backward-curved fan would be seriously affected, dropping say from 70 to 55 or 50 per cent. In such event, could a difference of speed be selected for the fan that would give the quantity desired at a higher efficiency? L. W. HUBER, Pittsburgh, Pa.-The backward-curved-blade fan responds to change in speed the same as any other fan; if' the speed is doubled, the quantity of air is doubled, the pressure is increased four times and the horsepower eight times. One point not mentioned in the paper is that the backward-curved fan is more efficient than the forward-curved or any other type. If the latter were more efficient, it would pay to install that type and keep the resistance of the mine constant, which is hard to do but it can be done with care. But the total mechanical efficiency of a fan with backward-curved blades is from 10 to 20 per cent. higher.

Jan 1, 1927

By K. J. Ma, L. Ma, J. Stankus

The paper’s intent is to evaluate pumpable foamed cementitious mine seal material by determining the shear strength of a generic foamed cement in the laboratory. The tests were conducted on three scales: small-size specimens, consisting of cylinders 4 in. in diameter or 3-in. prisms; double shear medium- size specimens, measuring 13 in. by 10 in.; and large-size specimens, measuring 6 ft by 4 ft by 4 ft. The small-specimen shear tests resulted in average peak and residual shear strengths of 128 psi and 56 psi, respectively. These values are fairly consistent with published shear strengths of foamed cementitious material. However, the other two types of shear tests did not achieve the shear strength of a typical pumpable foamed cementitous mine seal material. Based on the test results, the paper concluded that the structural analysis of cement foam seals should be based on their residual shear strengths, approximately 20 psi, determined from small laboratory-scale tests of the cement foam/concrete or rock interface, and not be based on their peak strengths.

Jan 1, 2015

By R. W. Smith, K. H. Lee Discussion by Fred C. Bond

Fred C. Bond (Tucson, Ariz.) — This is a valuable paper presenting much well directed research testing. It describes a practical method by which the long and relatively accurate Bond closed-circuit grindability can be adapted to a known ore so that results of comparable accuracy can be obtained on the same ore from much shorter batch grinding tests. This can be very useful in control work. In large mills a routine batch grinding test on the head sample can be made each day, or even each shift, to check grinding performance by comparison of the work index from each mill grinding section with that obtained from testing. However, it would be well to re-standardize the batch test against a Bond test, perhaps once a week at

Jan 1, 1969