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By Michel T. Halbouty

South Texas, one of the world's important oil and gas-producing areas, continued to hold interest during 1939 as another scries of new fields and new producing levels was developed within its boundaries at a fairly continuous rate throughout the year. There were 1801 wells drilled in this area in 1939, compared to 1678 in 1938; of these, 1515 were drilled in established fields, or as extensions to proven areas (semi-wildcat), and 286 were drilled as rank wildcats, in search of new production. Among these rank wildcats, 22 produced oil, 7 produced distillate and gas and 257 were abandoned as dry holes (see Table 5). Of the 1515 field and cxtension wells, 1213 produced oil, or distillate and gas, 50 produced only gas and 252 were dry; 38 found new productive sand levels in proven ficlds. Jim Wells County led this district in discoveries, having had 9 new fields arid 9 new productive sands found within its border during 1939. Most activc of the 1939 discoveries were Reynold?; and Ben Bolt fields in Jim Wells County and Minnie Bock field in Nueccs County; among producing fields the most activc were: East White Point and Aransas Pass (McCampbell). Production from South Texas in 1939 totaled 55,105,506 bbl. against a total of 56,152,122 bbl. produced in 1938. South Texas should continue its present rate of developrnent and exploration and this should result in the discovery of many fields in its numerous oil-bearing zones, and should also lead to more knowledge of the possibilities of its deeper horizons, such as the Mt. Selman and Wilcox formations; with the latter holding particular interest at the present time. Tide Water Associated Oil Company's A. M. Bruni No. I, Cole-Bruni field, Webb County, the deepest well drilled along the Mirando trend, was carried to 8959 ft., where it started to blow out from a Wilcox sand topped at 8954 ft., making gas, distillate and mud under heavy pressure. After the well was killed, drill stem beeame stuck and was cemented in place in order to test a Queen City (Mt. Selman) sand logged from 5620 to 5675 ft. This and other shows found in other wells along this trend, but out of this district, have served to increase the importance of this but little explored Sparta-Wilcox trend of South Texas during the year, and more activity along it is to be expected in the near future.

Jan 1, 1940

By M. E. Wadsworth, P. H. Yu, C. K. Hansen

A study of the rate of dissc5lution of chalcopyrite (CuFeS2) in acidic solutions under oxygen overpressures was carried out by measuring the rate of formation of cupric ions in solution. Effects of temperature, oxygen partial pressure, surface area, and concentration of sulfuric acid were evaluated. A sized batch of chalcopyrite was leached in the temperature range of 125° to 175°C and in the pressure range of 75 to 400 psi of oxygen. In 0.5 N H2SO4 all products of reaction went into solution except for trace amounts of elemental sulfur. The dissolution of chalcopyrite followed linear kinetics and was essentially independent of hydrogen ion concentration for H2S04 concentrations between 0.2 and 0.5 N. The oxygen dependence indicated adsorption approaching limiting values with increasing oxygen pressure. The linear mechanism was explained in terms of steady-state adsorption of oxygen at the chalcopyrite surface followed by a surface reaction. The enthalpy of activation for adsorption of oxygen was found to be approximately 33 kcal per mole. An activation enthalpy of approximately 9 kcal per mole was observed for the surface reaction. Charge transfer reactions are not rate controlling in the process.

Jan 1, 1973

By Ross W. Smith, Nikhil Trivedi

The variation of point of zero charge (PZC) of both simple and complex oxide minerals was studied as a function of aging time in water. In most cases the PZC's of the simple oxides moved toward more basic pH values with aging time. Evidence to date suggests that this phenomenon relates to dissolution of disturbed layers on the mineral's surface accompanied by later readsorption of metal hydroxy species back onto these surfaces. The readsorption takes place after the solution becomes supersaturated with respect to some crystalline phase. The variation of PZC's of complex oxides as a function of aging time in water is apparently related to several different mechanisms. In a few cases PZC shifted toward more basic values with time. This shift could be attributed to much the same mechanism as for simple oxides. In most cases, however, PZC of complex oxides shifted toward more acid values with aging time, probably because of loss to solution of soluble cations whose oxides possess basic PZC's.

Jan 1, 1975

By Carl Lee

WITH the modern trend toward motor drive in coal mines, more careful forethought should be given to future layouts than has usually been done in the past. Both top and bottom equipment of future new mines is likely to differ radically from those of a decade ago. No one is able to predict very far ahead, but provisions can be made to allow for uncertainty. One thing stands out: the mine of the future will be laid out for long life compared to that of the small mine of the past, where an inexpensive top plant, simple equipment, a small timbered shaft, small cars, light rail, hand loading and mule haulage all contributed to a short economical life.

Jan 1, 1933

By S. G. Lasky

EVENTS during and since the war indicate that the nations of the world are trying to initiate an era of international co-operation. Definitions and objectives include social, economic, and human considerations no less than political considerations. The mineral resources of the world and the absolute and relative position of each nation enter into this situation. The possible use of armed might, the application of sanctions, the international flow of commerce, the ways in which this flow may encourage or hamper international well-being, and the influence of international and domestic well-being upon one another are all matters that must take mineral resources into account. If the United States is to act wisely and forthrightly in such matters we must be thoroughly informed as to our position with respect to mineral resources. What is the mineral position of the United States? A variety of widely conflicting opinions are held in authoritative and intelligent quarters: (1) For practical purposes our mineral resources are already exhausted.

Jan 1, 1946

By W. M. Pierce

CORRUGATED sheet zinc has been used abroad for a great many years as a roofing material. In this country it has been in use for about 10 years. From the outset it was recognized that zinc sheets required closer spacing of the supporting purlins than steel sheets. Exact data regarding safe maximum fiber stresses were not available, however, and on occasions the span used was excessive and the sheets sagged. This paper describes both service and laboratory tests to determine safe maximum fiber-stress values for various grades of zinc for use in calculating the proper purlin spacings for any gage and profile under given loading conditions. These tests consist of laboratory loading tests on full-size roof sections over extended periods of time; of actual roof installations erected in conformity with the indications of the laboratory tests and observed over a period of years; of careful determinations of the apparent elastic limit of several grades of zinc, and finally of static tests1 (so-called creep tests) to determine the rate of flow of zinc under a variety of static tensile stresses at definite temperatures. Certain of the individual tests extended over a period of more than two years.

Jan 1, 1929

By C. W. Goodale

As an appendix to the above-mentioned paper, a drawing of the vertical projection of the Knoxville mine workings is here given. In my paper it was stated that the ore-chimneys are found along a crack or plane of cleavage in the limestone ; and as this crack is not parallel with the strata, it is safe to assume that the manganese was not deposited where it is now found before the tilting-up of the strata, but rather that the crack was caused by the folding, and that tile formation of the ore was entirely subsequent to the change of position of the limestone. There are here four chimneys, which have produced, as far as explored, over 12,000 tons of ore, containing at least 7000 tons of manganese oxides, and it is very difficult to apply Prof. W. P. Blake's theory of segregation from the surrounding limestone in accounting for the origin of this ore, as cross-cuts and drifts in the countryrock, even at short distances from the ore-chimneys, have not shown manganese in appreciable quantities. It is easier to believe that, in the language of .Mr. S. F. Emmons, in speaking of Leadville ore-deposits, there was a metasomatic interchange between the minerals brought in in solution and the limestone, and not a deposition in already existing cavities. This in-

Jan 1, 1890

By R. Ward Grosz

Reasonable and timely solutions to the complicated mathematical calculations involved in the mine planning, economic evaluation and slope stability studies related to the Ruth Mine would not have been feasible without the modern digital computers. The Ruth Mine was a prosperous underground copper operation in east central Nevada from 1915 to 1948, when rising mining costs finally exceeded the value of the ore. A substantial reserve of porphyry copper remained in the ground, but until recently all economic evaluations indicated that it was at best a marginal operation and a relatively poor risk of capital. There has been a steady progress in improving all aspects of surface mining since the first steam shovel started stripping overburden; however, developments in just two rather specialized areas proved to be critical in changing the Ruth Mine from a reserve of mineralized rock to an economically attractive orebody. One involved the progress made in recent years in the science of slope stability. Applying the latest techniques in this field to mine planning resulted in reducing the stripping ratio from 6.0:l to 4. 2:l. The other major factor was the efficiency and cost performance of large capacity haulage trucks which made it feasible to go down over 1100 ft. in an open pit and recover ore with a high stripping ratio economically.

Jan 1, 1969

By John McDonald

THIS report is a continuation of an earlier one with a similar title,1 to which the reader is referred for such details of procedure as do not appear here. A brief summary will be given of the objects and methods of the research at this time. It was pointed out in the previous paper that properties of magnesium alloys, as re-ported by different workers, often differ. This was thought to be due to differences in the preparation of the specimens tested. The ideal way to compare alloys would be to prepare each of them in so many ways that reasonable assurance would exist that the best properties of each alloy had been developed. The alloys would then be com-pared on the basis of these properties. The treatment actually given the alloys of these studies is necessarily a compromise with completeness. Nevertheless, enough treatments have been given so that a con-siderable degree of assurance exists that the properties obtained are representative of the alloy as such, and not merely of the manner in which it was worked and heat-treated.

Jan 1, 1940

Victor G. Hills, Cripple Creek, Colo. (communication to the Secretary): In continuation of the subject of the perform ance of "baby machine-drills," presented by Mr. Thane, I sub mit the following records of work done with these drills in the Cripple Creek district of Colorado. Two years ago, the Anchoria-Leland mine began to use baby drills ; and, to make the experiment more complete, began by purchasing two machines, of the same size, but of different make. The little drills were first used for stoping and up raising, in which they achieved at once an unqualified success. Soon after, they began to be used for the smaller branch-drifts and prospecting cross-cuts, while the large two-man drills were still used for the main drifts. Now they have almost entirely superseded the large drills, since it has been found that they will do any ordinary work in the mine at less cost, both for labor and for powder, per ton of rock broken. The large drills, of course, make more rapid progress; but it is only where time is a specially important factor that they are now used. The Portland mine, where, until within a year, only the large machines were used, is now using some small drills for stoping, and also for drifting. Mr. Thane speaks of having two men to operate a baby-drill; but in this district the baby-machine is always worked by one man without help. Again, in Prof. Christy's postscript, the quoted extract from a letter of Mr. L. T. Seymour, the South African engineer, mentions a " 2 1/2-inch Little Giant," as though that were the smallest machine used in that region. These statements leave some doubt as to just what Mr. Thane means by a " baby-drill." To avoid any such uncertainty as to the present communication, I will say that the large or two-man drill in common use at Cripple Creek has a 3 1/8-inch cylinder; while a few mines employ a 3-inch, and a few, in running large tunnels, a 3 1/2-inch drill. What we call a baby-drill here has a

Jan 1, 1900

The following is an incomplete list of members and guests who called at Institute headquarters during the period Apr. 10, 1919, to May 10, 1919. Arthur K. Adams, Spencer, Mass. Ensign Floyd D. James, U. S. S. Fulton. W. T. Bates, New York City, N. Y. J. Harry Johns, Thorsden, Woking, A. D. Brokaw, Washington, D. C. England. E. H. Clausen, San Francisco, Calif. W. F. Jones, Rock Springs, Wyo. W. M. Corse, Mansfield, Ohio. E. L. Lasier, Washington, D. C. E. O. Daue, Philadelphia, Pa. John M. Lovejoy, New Rochelle, N. Y. G. D. Dub, Washington,, D. C. 2d Lieut. James F. Magee, Lancaster, S. B. Eaton, Dover, N. J. Pa., Sherman Eaton, Smethport, N. C. Ernest Marquardt, Casper, Wyo. J. A. Endweiss, La Jolla, Calif. Geo. B. Marshall, Abangarez, Costa Edgar W. Engle, North Chicago, Ill. Rica. 2d Lieut. Maxwell E. Erdofy, New York Benj. L. Miller, So. Bethlehem, Pa. City, N. Y. Major Desaix B. Myers, Camp Mills. Chas. A. Fellencer, Allentown, Pa. Edmund Newton, New York City, N. Y. Arthur Feust, Joplin, Mo. Seely B. Patterson, Jr., Allentown, Pa. Ensign Harold P. Ford, U. S. S. Radnor. Wm. R. Pearson, New York City, N. Y. A. D. R. Galloway, Accra, West Africa. Harold C. Price, Langeloth, Pa. R. C. Gosrow, Milwaukee, Wis. T. C. Roberts, East. Orange, N. J. C. A. Grabill, El Paso, Tex. P. H. Royster, Washington, D. C. Hobart A. Hanks, San Francisco, Calif. W. H. Staver, New York City, N. Y. John L. Henning, Lake Charles, La. N. L. Wimmler, Bangkok, Siam. 1st Lieut. J. Parke Hook, Philadelphia, Capt. Jay P. Wood, New York City, Pa. N. Y. An item in the May Bulletin made it appear that Frank W. DeWolf had just become connected with the State Geological Survey of Illinois. This was one of the inadvertences of war. Mr. De Wolf has been Director, or Chief, of the State Geological Survey for approximately ten years. Through the courtesy of the Governor of Illinois, lie was loaned to the Bureau of Mines for about seven months, after which period he resumed his former position.

Jan 6, 1919

By Michael Chender

The current outlook for financing new copper production is not very encouraging. At a time when companies are slogging through a protracted period of low prices as well as having to accept lower profits due to more stringent tax and royalty schedules, banks are beginning to require companies to take a greater equity interest in new projects. Mineral resource financing, including copper, seems to have lost much of its appeal to the lending institutions, and loans of any kind to many of the developing countries -from which over half of new copper capacity could be expected to come-are being examined much more critically than they were in the late 1960's and early 1970's.

Jan 12, 1976

By R. H. Wightman, G. H. Adams

In order to secure good results in the prevention of accidents, it is generally recognized that the desire for such accomplishment, as well as the aggressive and constructive action to achieve it, must emanate from the Top Management and permeate successively down through the "Chart of Authority" to the workmen. Several years ago, with the above as a basis and with full support of the Top Management, the Mining Department started a program of selling the foremen and bosses the idea that safety could be achieved and that it was desired and required. Using psychology, persistence and numerous other methods, the foremen and bosses were finally impressed with the idea that "It can be done" and "It will be done." With this in mind, new ideas were brought forth by the foremen and bosses regarding the caving operation and the specific jobs in the operation. These new ideas were taken up in round-table discussions and resulted in certain changes in the undercutting method and the actual drawing of the blocks. These changes resulted in increasing fragmentation of the blocks which prevented the usual hang-up areas in the blocks. With the rock smaller in size and within reasonable reach from the tapping drifts, accidents were prevented in the tapping section. At the same time, an enforced campaign of housekeeping throughout the mine was undertaken with very beneficial results. The foremen and bosses then, in turn, educated and trained the workers themselves to become safety conscious. In so doing, a constant reminder was given on all jobs assigned that the job was to be done safely as well as efficiently. No man is assigned a job who is not qualified for the type of work required. Efficiency and safety go hand in hand. Safety Rules To supplement and aid this safety conscious attitude, certain safety rules applicable to our operation, a modified block caving system of mining limestone, in addition to the established state regulations, were put into effect and enforced. The specific rules referred to above and which will be mentioned below are in most cases simply a means of applying and complying with the very adequate "Mine Safety Orders" issued by the Industrial Accident Commission of the State of California. Some of the safety rules and policies are as follows: All men are required to wear safety

Jan 1, 1950

Jan 1, 1915

By W. S. Pellini, F. N. Rhines

IN many of the otherwise well established alloy phase diagrams the solidus curves (temperatures at which liquid first appears upon melting) have not been located accurately, chiefly because the experimental techniques that have been most popular for determining solidus temperatures have been both cumbersome and subject to large errors. C. E. Homer and H. Plummer1 have described a sensitive and at the same time a very simple technique for locating the solidus curves in a number of alloys of tin. Their method consists simply in noting the temperature at which a specimen of the alloy ruptures under the influence of a light bending force. Although this method is not new, it has been little used for this purpose in the past; nevertheless, it appears so attractive in its possibilities of speed, simplicity, and precision that the investigations presently to be described were undertaken to verify its merits. The redetermination of the solidus and eutectic temperatures of the lead-antimony system was employed as a medium 0f experimentation. New values obtained in this way are believed to be sufficiently precise to warrant a revision of the currently accepted lead-antimony phase diagram (Fig. I). Determinations of the solidus of the lead-rich lead-antimony alloy series have been published by R. S. Dean2 and by E. E. Schumacher and F. C. Nix.3 Their points are represented in Fig. I. In their work the solidus was not located at antimony concentrations greater than 2 per cent; the curve was presumed to meet the eutectic horizontal at an antimony concentration of about 2.5 per cent. In the present studies the solidus has been traced to 3.5 per cent, where the eutectic horizontal is intersected (Table I and Fig. I). Within the range investigated by Dean and by Schumacher and Nix the agreement with their values is good. H. Seltz and B. De Witt,4 on the basis of activity measurements, have calculated that the intersection of the solidus and the eutectic reaction horizontal should lie at 3.86 per cent of antimony. The following determinations of the eutectic temperature have been reported: Roland-Gosselin,5 228°C.; Ewen,6 228°C.; J. E. Stead,7 247°C.; Campbell,8 228°C.; W. Gontermann,9 245° to 252°C.; R. Loebe,10 245°C.; E. Heyn and 0. Bauer,11 245°C.; H. Endo,12 250°C.; R. S. Dean,2 249° to 258°C.; E. Abel, 0. Redlich, and J. Adler,13 245°C.; W. Broniewski and L. Sliwowski,14 250° to 252°C.; H. Seltz and B. De Witt,4 250°C. A temperature of 249°C- appears to have been generally accepted in recent years; it is the value most frequently obtained by the method of cooling curves. Values below 249°C. have usually been obtained by inferior cooling-curve techniques; those above 250°C., by the method of heating

Jan 1, 1942

By F. N. Rhines, W. S. Pellini

In many of the otherwise well established alloy phase diagrams the solidus curves (temperatures at which liquid first appears upon melting) have not been located accurately, chiefly because the experimental techniques that have been most popular for determining solidus temperatures have been both cumbersome and subject to large errors. C. E. Homer and H. Plummerl have described a sensitive and at the same time a very simple technique for locating the solidus curves in a number of alloys of tin. Their method consists simply in noting the temperature at which a specimen of the alloy ruptures under the influence of a light bending force. Although this method is not new, it has been little used for this purpose in the past; nevertheless, it appears so attractive in its possibilities of speed, simplicity, and precision that the investigations presently to be described were undertaken to verify its merits. The redetermination of the solidus and eutectic temperatures of the lead-antimony system was employed as a medium of experimentation. New values obtained in this way are believcd to be sufficiently precise to warrant a revision of the currently accepted lead-antimony phase diagram (Fig. I). Determinations of the solidus of the lead-rich lead-antimony alloy series have been published by X. S. Dean2 and by E. E. Schumacher and F. C. Nix. Their points are represented in Fig. I. In their work the solidus was not located at antimony collcentrations greater than 2 per cent; the curve was presumed to meet the eutectic horizontal at an antimony concentration of about 2.5 per cent. In the present studies the solidus has been traced to 3.5 per cent, where the eutectic horizontal is intersected (Table I and Fig. I). Within the range investigated by Dean and by Schumacher and Nix the agreement with their values is good. H. Seltz and B. De Witt,4 on the basis of activity measurements, have calculated that the intersection of the solidus and the eutectic reaction horizontal should lie at 3.86 per cent of antimony. The following determinations of the eutectic temperature have been reported: Roland-Gosselin,5 228°C.; Ewen,6 228OC.; J. E. Stead,7 24g°C.; Campbell,8 228°C.; W. Gontermann,9 245' to 252°C.; R. Loebe,lo 245°C.; E. Heyn and 0. Bauer,ll 245°C.; H. Endo,12 250°C.; R. S. Dean,= 247' to 258°C.; E. Abel, O. Redlich, and J. Adier,13 245°C.; W. Broniewski and L. Sliwowski,14 250' to 252°C.; H. Seltz and B. De Witt,4 25o°C. A temperature of 247°C. appears to have been generally accepted in recent years; it is the value most frequently obtained by the method of cooling curves. Values below 247°C. have usually been obtained by inferior cooling-curve techniques; those above 250°C., by the method of heating

Jan 1, 1943

By W. S. Pellini, F. N. Rhines

In many of the otherwise well established alloy phase diagrams the solidus curves (temperatures at which liquid first appears upon melting) have not been located accurately, chiefly because the experimental techniques that have been most popular for determining solidus temperatures have been both cumbersome and subject to large errors. C. E. Homer and H. Plummerl have described a sensitive and at the same time a very simple technique for locating the solidus curves in a number of alloys of tin. Their method consists simply in noting the temperature at which a specimen of the alloy ruptures under the influence of a light bending force. Although this method is not new, it has been little used for this purpose in the past; nevertheless, it appears so attractive in its possibilities of speed, simplicity, and precision that the investigations presently to be described were undertaken to verify its merits. The redetermination of the solidus and eutectic temperatures of the lead-antimony system was employed as a medium of experimentation. New values obtained in this way are believcd to be sufficiently precise to warrant a revision of the currently accepted lead-antimony phase diagram (Fig. I). Determinations of the solidus of the lead-rich lead-antimony alloy series have been published by X. S. Dean2 and by E. E. Schumacher and F. C. Nix. Their points are represented in Fig. I. In their work the solidus was not located at antimony collcentrations greater than 2 per cent; the curve was presumed to meet the eutectic horizontal at an antimony concentration of about 2.5 per cent. In the present studies the solidus has been traced to 3.5 per cent, where the eutectic horizontal is intersected (Table I and Fig. I). Within the range investigated by Dean and by Schumacher and Nix the agreement with their values is good. H. Seltz and B. De Witt,4 on the basis of activity measurements, have calculated that the intersection of the solidus and the eutectic reaction horizontal should lie at 3.86 per cent of antimony. The following determinations of the eutectic temperature have been reported: Roland-Gosselin,5 228°C.; Ewen,6 228OC.; J. E. Stead,7 24g°C.; Campbell,8 228°C.; W. Gontermann,9 245' to 252°C.; R. Loebe,lo 245°C.; E. Heyn and 0. Bauer,ll 245°C.; H. Endo,12 250°C.; R. S. Dean,= 247' to 258°C.; E. Abel, O. Redlich, and J. Adier,13 245°C.; W. Broniewski and L. Sliwowski,14 250' to 252°C.; H. Seltz and B. De Witt,4 25o°C. A temperature of 247°C. appears to have been generally accepted in recent years; it is the value most frequently obtained by the method of cooling curves. Values below 247°C. have usually been obtained by inferior cooling-curve techniques; those above 250°C., by the method of heating

Jan 1, 1943

Jan 1, 1925

Executive Committee, Board of Directors Augustus B Kinzel, Chairman, J L Glllson, Vice-Chairman, A W Thornton, Howard C Pyle, Grover J Holt Finance Committee, Board of Directors Andrew Fletcher, Chairman, J S Vanick, Gall F Moulton Investments Gail F Moulton, '60, Chairman, Henry Krumb, '59, J Loveloy, '61, C R Dodson, ex off as Treasurer, Andrew Fletcher, ex off as Chairman, Finance Com¬mittee Endowment Andrew Fletcher, Chairman, N G Alford, H DeWitt Smith, W J Coulter, J V N Dorr, R B Gilmore, J B Haffner, O H Johnson, D H McLaughlin, J R McMillan, L F Reinartz, C E Weed, Wilfred Sykes, J R Suman Honorary Memberships H DeWitt Smith, '59, Chairman, C E Reistle, Jr, '59, Grover J Holt, '59, L F Reinartz, '59, M L Haider, '60, D H McLaughlin, '61, John M Lovejoy, '62, Augustus B Kinzel, ex off as President

Jan 1, 1958

By L. D. Frink

Those actively interested in mining are fully aware of the ever-increasing difficulty of making conditions such that efficient work can be done in underground openings, especially as higher rock temperatures are encountered in depth. This is also true where an effort is being made to cut down the burden of overhead expense by working headings 24 hr. in a day if blasting is done as often as is possible in that time. That the conditions resulting from both these causes have driven the native-born Americans from the mines and that their places have been taken by less efficient foreigners is a fact that we must all admit. The great war now being fought in Europe and the educational qualification clause written into our immigration law by the last Congress will probably limit very materially the supply of labor, such as we are now using in our mines, and will force upon mine operators the necessity of making this work appeal again to Americans. Metal tubing, with blower or exhaust fans, has long been used in supplying air to dead ends where natural ventilation is impossible, or in driving the smoke from such places, or in doing both, as the need might be. Here in Butte we have now come to use canvas tubing very extensively and find that it has many advantages not possessed by the metal. The use of flexible tubing is not new, but it has not been generally used in mining operations. Recent improvements, however, in the canvas itself and in the jointing of sections and manner of suspension have so increased its usefulness that it promises to add much to the efficiency of mining. There is now on the market a product that is impervious to air, is fireproof, and has a system of jointing which permits it to be put up or taken down in a few seconds. In this article an effort will be made to explain the manner in which canvas tubing is being used in the North Butte company's operations at Butte, Mont. The accompanying photographs will, I hope, help make clear what may be done with this material.

Jan 1, 1918