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By Randhir Sehgal

If the primary purpose of a control system is to assure a fixed-quality product at maximum yield, the real issue involved in control of the fine coal cleaning circuit in a plant is to demonstrate that control is technically feasible and economically beneficial . This paper suggests that it is not easy to do so in most cases. Fine coal, defined here as the 28 mesh x 0 fraction of the plant feed, is generally cleaned using a combination of hydrocyclones and flotation. Both of these processes are relatively insensitive to changes in operating variables. Further, the fines fraction general 1 y forms no more than 20% of the plant feed and, at times, is as low as 10%. The instruments to measure flow rates, densities, and product qua1ity (ash, sulfur, etc.) are not sufficiently accurate to allow effective responses to changing state variables and product quality. It is sufficient to run the fine coal circuits at maximum recovery, and the control of product quality and optimization of yield should be achieved by controlling the coarse coal circuits and measuring the quality of the entire clean coal leaving the plant. This contention is made with particular reference to U.S. plants cleaning coal for the utility industry and should be viewed in this context only. It is explicitly admitted that this strategy is mathematically non-optimal in the sense that all size fractions are not necessarily cleaned at equal elementary ash, and would result in a loss of yield. However, under the conditions of conventional coal cleaning practice, this is a sensible approach.

Jan 1, 1988

By R. Worrall

The global mining industry has been proactive over the last decade in finding ways to embrace the concept of sustainability. However, legacy mine sites (which include abandoned derelict and orphan mine sites) across the world continue to present issues for the global mining community, governments, local communities and NGOs. Unfortunately there has been much less academic focus on this area of mining and sustainability. This paper seeks to address how principles of sustainable development can be used to guide the development of processes for addressing post mining landuse issues for legacy mining areas. This is being done using a case study area located near Ipswich, in southeast Queensland, Australia. This area has a 160 year history of coal mining, and was one of Queensland?s crucial early industries. Mining in the area ceased in 2003 leaving a degraded landscape covering an area in excess of two thousand hectares adjacent to one of the fastest growing urban areas in Australia. A sustainability criteria and indicators framework for post-mining landuse on legacy mined land, developed from current best practice used for measuring sustainability across a range of industries is being developed. A review of current best practice suggests the framework should: (1) consider in equal measure environmental, social and economic factors; (2) have a minimum number of indicators which should be easy to identify and measure; (3) must have indicators with a meaningful output; and overall, the framework must consider particular requirements of the site being investigated. Application of the framework to the case study area is an ongoing aspect of this research, and the results will be evaluated through the use of expert stakeholders.

Jan 1, 2007

By Charles C. Upham

Not long ago a few acres of coal-land in the Connellsville region of Pennsylvania were sold at the rate of $1500 per acre. While this was doubtless a " fancy " price, affected by some consideration other than that of the simple value of the coal in the tract. it may fairly be taken as an indication of a progressive and already perceptible diminution in the economically available coal-resources of that famous region. This piesent and prospective development emphasizes the cominercial importance of producing, from the inferior coals of other districts, coke suitable for use in the blast-furnace. Many of the bituminous coals of the United States would meet this requirement if sufficiently freed, before coking, from slate and sulphur, and, so far as the removal of slate is concerned, the problem is not specially difficult. There are many forms of trough-, jig- and gravity-washers which easily and cheaply reduce the slate from as much as 20 per cent. in the coal to as little as 8 per cent. in the coke. But to reduce the sulphur from 4 per cent. in the coal (a proportion sometimes encountered) to 1 per cent. or less in the coke (the proportion demanded by the furnace-manager) is not so easy. It may be safely assumed as familiarly known to members of the Institute interested in this subject that, of the three forms in which sulphur usually exists in coal (hydrogen sulphide, calcium sulphate and pyrite), the pyrite is the one to be removed, RS far as possible, by mechanical treatment before coking. Hydrogen sulphide, being volatile, is expelled in

Jan 1, 1899

By David A. Thomas, John F. Peck

Sam Leber (General Electric Refractory Metals Laboratory)—I think that the authors should differentiate between the curved grains obtained by swaging and the crumpled grains produced by drawing. This can be seen most easily in the transverse sections of Fig. 2d, and is also apparent in Fig. 2c. This difference in structure indicates that the mode of deformation shou1d affect the texture, since the cylindrical texture should be maintained or even increased by the curved grains developed by swaging. Drawing, on the other hand, crumples the grains. This should convert the cylindrical texture into a normal fiber texture. This has been substantiated by a comparison of tungsten wires fabricated by similar drawing and swaging schedules. Although cylindrical textures have been detected in drawn iron wires, they were weak in comparison to tungsten wires which included swaging as part of the fabrication process. It should also be noted that large curved surfaces developed by swaging are concentric with the surface. The postulated (100) surface of these crystals would be confirmed by a (100) cylindrical texture, as was observed in tungsten. The preservalion of the (100) cylindrical texture by swaging would maintain the <100> direction in the radial position required for easy flow. This might provide a partial explanation for the decreased rate of work hardening observed in the swaged wire. J. F. Peck and D. A. Thomas (authors&apos; reply) — The authors appreciate Dr. Leber&apos;s comments on the differences in textures, microstructures, and properties of swaged and drawn wires. The evidence of the prominence and persistence of the cylindrical texture in swaged bee wires seems quite consistent with our microstructural observations and interpretations. We are presently engaged in further work to correlate the development of texture and micro-structure in drawn bee metals.

Jan 1, 1962

My closest personal connection with the problems of rehabilitation comes from two years spent on a project at Weipa. At the beginning I am fairly certain that the engineers did not understand the mental processes of the ecologist they were dealing with. I am absolutely certain that the ecologist did not understand the minds of the engineers. This form of the two cultures problem is the root of some of the matters that lie behind this lecture. It is possible to establish a stabilising cover of vegetation on virtually any land surface, short of a cliff. While the biologist knows this he also knows that the physical and chemical nature of a given acre of land combines with climate to define quite sharply just what plants can be grown there. In the case of land after mining the range of plants may be quite limited. The engineer, and his masters in the accounting section, seem (in my experience) to expect that rehabilitation can be carried on with equal speed and facility in any location. This belief commonly leads to a situation where rehabilitation is not considered until mining is well under way. True, the mine must be proved as an assured profit- earner before money can be justified for the non-productive (to the miner) expense of rehabilitation. But when the miner finally starts rehabilitation he does not always get a convincing and speedy result. Furthermore, the failure may not be easy to overcome. This is even more likely to be the sequence of events if the miner wants, or is obliged, to specify the exact type of vegetation to be produced, e. g. commercial forest, pasture,&apos; or the original native vegetation.

Jan 1, 1971

By Edward H. Robie

Engineers&apos; Centennial THIS summer, in Chicago, will be celebrated the "Centennial of Engineering" and half a hundred engineering societies will have meetings of one kind or another in the two weeks following Labor Day. It is really the 100th anniversary of the founding of the American Society of Civil Engineers. Centennial of Engineering is merely a convenient label to put on the celebration of 100 years of engineering progress in this country since the ASCE was founded. Engineering, of course, is much older than is thus indicated-thousands of years older. But Americans have a penchant for dramatizing progress by celebrating assumed anniversaries. Four years ago a special 30 stamp was issued on which a Brahma chicken was prominently displayed, with the legend, "1848-1948. Centennial of the American Poultry Industry." We feel reasonably sure that the first dozen eggs was sold considerably earlier than that. Until a hundred or so years ago engineers were generally classified as either military or civil. Apparently a group of civil engineers met for the first time in Augusta, Ga. but no records were kept and the first meeting of which we have definite knowledge was at Barnum&apos;s Hotel in Baltimore, Feb. 11, 1839. Forty engineers were present and they decided to form a society. Among the aims of these engineers was "the greatest amount of useful effect at the smallest cost," which is as good a slogan for the engineer of today as it was 113 years ago. It was mentioned that the existence and prosperity of the society depended in no small degree on "the personal conduct and exertions" of the members. "Talents and respectability are preferable to numbers ... from too easy and promiscuous ad mission, unavoidable, and not infrequently incurable, inconveniences perplex most societies."

Jan 1, 1952

The reduction of titanium tetrachloride to trichloride can be achieved by employing hydrogen and electric arcs. It is possible to produce melts containing up to 50% TiCk in the eutectic mixture of LiCl/KCl by striking a D.C. arc at the surface in the presence of hydrogen and TiCl. vapour. If the electrode IS made to just penetrate the surface of the salt mixture, a hot zone results from the&apos; high resistance contact with both lower chlorides and sintered titanium may be produced. The sintered metal forms just below the melt surface while the trichloride forms at the gaslIiquid junction.The &quot;hotspot cathode&quot; appears to offer a solution to the problem of producing coherent deposits as the spong&apos;e metal can &apos;be continuously withdrawn in a similar manner to the &quot;calcium process&quot;.INTRODUCTIONConsiderable interest has been shown for some years in the possible development of a cheap electrolytic process for the extraction of titanium metal, since a method using simple materials and cheap electric power would materially reduce the cost of production. Even when cheap starting materials are used, however, there exist several general difficulties in the operation of plant which both limit the speed of production and increase the cost of the product. It happens that most of the techniques so far tried produce a powder as cathodic deposit, and when this is the case the following difficulties arise:1. The whole contents of the bath must be treated with solvent in order to extract the &apos;metal powder which may itself tend to oxidise, and thus become contaminated.2. Fine metal powders, which often contain residual entrained salts, are less easy to consolidate by arcmelting than metal sponge.

Jan 1, 1956

By W. J. Sharwood

Discussion of the paper of W. J. SHARWOOD, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 104, August, 1915, pp. 1671 to 1675. FREDERIC P. DEWEY, Washington, D. C. (communication to the Secretary*).-Even if the data given should be considered sufficient to support properly the empirical rule as stated, this rule would be of extremely limited application in miscellaneous assaying. Tile fixed conditions must include equality of gold and silver where mixed beads are concerned, owing to the wide variation in the specific gravity of gold and silver. Also, the fixed conditions must include the presence of the sane amounts of other base metals besides lead. Such an agreement is .often lacking even in the beads from two fusions of the salve ore. In practical work it is sufficiently general to be called universal that cupellation beads are not pure precious metal. An apparent loss in cupellation is an algebraic sum and in many cupellations the gains exceed the losses, especially with large beads where tile gains lie so completely in the judgment of the cupeller. For several years I have been engaged in an investigation into the conditions affecting the accuracy of gold-bullion assaying, and have just completed an examination of cupels which included the assaying of 10,000 used cupels. The grand result of the cupel work is an emphatic warning against drawing rigid conclusions regarding cupellation. It is so easy to say "If all other conditions remain the Same," but it is extremely difficult, and in practical work impossible, to maintain equal conditions. Cupel absorptions, which constitute such a large proportion of cupellation losses, and in many cases the only loss, may vary considerably in different parts of the same row of cupels, even in carefully regulated work.

Jan 12, 1915

By N. S. Kenny, A. A. Burr

THE purpose of this note is to present evidence that vacancies, which have been produced by quenching from a high temperature, alter the rate of strain-hardening of an hep single crystal. The majority of investigations of the effects of quenched-in vacancies on the yield stress of metals have been made using fee samples in the form of thin wires. However, there is an inherent disadvantage in using such wires to study the effects of vacancies on the rate of strain-hardening of metals because fee wires begin stage II slip either immediately upon yielding or very shortly thereafter. When stage II slip occurs, very rapid strain hardening also occurs, masking the effects of vacancies on the rate of hardening. In this investigation single crystals of magnesium hep were studied since magnesium has only one slip plane at low temperatures and has, therefore, an extensive easy glide region. In addition, the effect of both static and dynamic recovery on the rate of hardening were eliminated by testing in liquid nitrogen. Both forms of recovery occur in hep metals by dislocation climb, which is a diffusion controlled mechanism and is negligible at liquid nitrogen temperatures. Finally, the dependence of the strain-hardening rate on the crystal orientation was eliminated by using the equations of Schmid and Boas.&apos; Variations in the strain-hardening rate could, therefore, be attributed to the presence of vacancies. Single crystals in the form of rods approximately 5 mm in diam and 6 cm long were grown by a modified Bridgman technique from commercial high-purity magnesium (99.97 pet) supplied by the Dow Chemical

Jan 1, 1962

Discussion of the paper of COURTENAY DEKALB, presented at the New York meeting, February, 1915, and printed in Bulletin No. 98, February, 1915, pp. 331 to 337. HORACE V. WINCHELL, Minneapolis, Minn.-Mr. Dehalb summarizes the reasons which he believes are important for the revision of the mining laws, as follows: "1. The conceptions as to the characteristics of orebodies that were held at the time the statute of 1872 was enacted have since proved to be in many respects erroneous." We all appreciate the force of that suggestion. The idea of the old prospector who made rules and regulations in the early days, which were attempted to he incorporated, so far as possible, in the Mining Act of 1872, was that all of the veins in a certain district outcropped upon the surface, or approximately parallel to each other upon the surface, and maintained that parallelism beneath the surface. Therefore, it seemed perfectly proper and natural for each man to stake his claim upon an outcropping, and have the right to follow that vein in working downward, with the general expectation that his workings would always remain just as far away from those of his neighbor as the outcroppings upon the surface. This does not happen to be the case. Dr. Raymond has very ingeniously referred to the subject in one case, in words which read as follows: "If all mining properties presented this beautiful simplicity of structure (ideal location of ideal vein), and all mining locators exhibited a corresponding simplicity of purpose, the application of the law would be easy, but the naiveté of the statute fares badly between the freaks of nature and the tricks of man."

Jan 5, 1915

By R. C. Beckstrom

Russia&apos;s first "Petaletka&apos;&apos; has ended. Technically it did not succeed but practically it has been a great achievement in the petroleum industry. Out of the chaos of revolution and civil war Russia has developed her oil industry to second place in the world&apos;s production. For 1932 production of crude oil is estimated at 150,000,000 bbl. and refined products at 145,000,000 barrels. Russia has been able to give the petroleum industry every advantage that a government can extend to a fast growing industry. She has obtained all of her property by confiscation. Under government ownership, operation and control, her petroleum industry is not handicapped in any way by state rulings or by unnecessary competition in production, refining and marketing. There are no damage suits resulting from offsetting, flooding, repressuring, laying of pipe lines, building of docks or other necessary work. Russian oil fields2 have been easy to develop and operate. They lie advantageously to transportation for foreign markets. The chief disadvantages have been a lack of credit and technical cooperation, but the former is being overcome by the sacrifice of the people. They go without the comforts of life that all salable articles may be exported for the imports of modern machinery. Modern machinery is fast replacing the obsolete and worn-out equipment. Technical cooperation has been difficult because it has been necessary to train thousands of adults to do technical and mechanical work. Great quantities of pipe, tools and electrical equipment were necessary for the rapidly developing fields and refineries. The supplies have been inadequate and the quality poor. This lack of equipment, along with the untrained technical supervision, has been the cause of the proposed quota falling short. Fig. 1 shows the production for 1931 and 1932. During 1932 a large percentage of the oil was produced in the proven fields of the Caucasus.

Jan 1, 1933

Oxy-ACETYLENE system of welding and cutting is at present practised in two forms, which may be described as the high and lowpressure systems. In the high-pressure system the two gases, oxygen and acetylene, are delivered. to the blow-pipe under pressure from properly constructed trade cylinders. Oxygen cylinders are in two sizes, each containing 100 and 200 cub. ft. of gas respectively. These cylinders are charged to a pressure of 120 atmospheres, or 1800 lb. per sq. in. approximately. The acetylene cylinders are made in one size as far as the writer knows, and contain 200 cub. ft. of acetylene gas at a pressure of 10 atmospheres. Each cylinder is provided with a valve and connection for attaching a regulator to &quot;break down&quot; the high pressure in the cylinders to the necessary low working pressure of the blow-pipes, and to deliver the two gases at a constant pressure irrespective of the variable pressures in the cylinders. These regulators can be adjusted down to as low as 1 lb. and are provided with two pressure gaugesone reading the contents of the cylinder in atmospheres, and the other the working pressure in lb. per sq. in. The high-pressure, or &quot;two cylinder&quot; system is compact and can readily be transported from place to place in the works. For this purpose the two cylinders are mounted on an easy-running 4-wheeled truck, which the operator and assistant find no difficulty in manipulating. In the low-pressure system the two gases are delivered to the blow-pipe, one from the oxygen cylinder and the other from the acetylene gas generating plant, which consists of the following:Generating cylinder, half filled with water, into which the cathoide is plunged. The generated gas is passed through a filter to the gasometer, then through a water washer on to the hydraullic seal...

Jan 1, 1922

By E. D. Gardner

VICTOR G. HILLS, Denver, Colo. (communication to the Secretary*).¬If anyone advocates the abolition of the antecedent mineral discovery requirement for the purpose of making it easier to secure title to public land, I hasten to say that I am not of that number. I am in Hearty accord with all that Mr. Gardner has to say in regard to easy patenting as a handicap to small camps, and that in general it acts to retard the mining industry. And the following sentences I want to repeat in order to emphasize and endorse them, "None of the writers on this subject seem to have taken into consideration the effect amending the law pertaining to mineral discovery will have upon the Government&apos;s administration of the public land. It must be borne in mind that this land belongs absolutely to the people of the United States as a whole, and their interest must be considered. It is not a no-man&apos;s land, as some people would appear to believe." However, I believe that the discovery prerequisite should be abolished, because it fails to effect the protection for which it was designed, and I look for other provisions that will better serve the purpose. We propose to abolish the law of apex not because the theory is objectionable but because the question of physical fact gives rise to never ending litigation. Now the design of antecedent mineral discovery is good; the court rulings are unobjectionable; but when it comes to the physical fact this requirement is second only to the apex law as a healthy litigation breeder. The only circumstance that has prevented the pre-discovery lawsuits from becoming as famous and as: expensive as the apex

Jan 12, 1916

By Dae-Woo Kang, Sang-Wook Kim, Shin Lee

The Air-tubes blasting method is provided in which a series of aligned boreholes are charged with explosive s and air tubes in a predetermined blasting pattern. The air tube is composed of cylindrical flexible tubes which have a predetermined width and length to be fit with the site boreholes. Within a preferred formation, each borehole is charged with the explo sives and detonators with an air tube installed just above the explosives. Stemming materials are filled above the air tubes. At the limestone mine of Sung-Shin Cement Co., in South Korea, these blasting tests were performed by a diameter 102 millimeter and 15 m long boreholes with the charging length of explosives was 8m to 10 m by the total weight of explosive 40 to 50 kg with 3m to 6m air tube which has a 76 mm diameter, and 1m to 3m stemming cover. Blasting results showed the about 10% to 30% explosives savings available and especially, the about 20% to 50% reduction of ground vibration with the low noise measures around 2dB to 5dB by this new blasting method which was compared with the conventional blasting methods. The explosives and air tubes may be alternately charged along the boreholes. The use of air tubes which were charged above an explosive layer allow to form the quantitative air decking in every blast hole. Therefore, the Air-deck effect can be easily obtained through this blasting method, and also easy to increase the fragmentation rate resulting in the more suitable mucking procedures at the working site with the minimum usages of explosives for the better economic operations in mine quarries.

Jan 1, 2005

By M. P. Boss

Of the two methods of mechanical reduction—that of percussion and that of abrasion—it is not easy to say which was first employed by primeval man. The stone hammer and the flat or hollowed stone used for grinding are found together in the remains of prehistoric periods. But the use of the maray, or bucking-stone, developed from the hammer, was probably introduced later than that of crude millstones. Diodorus Siculus, the Roman historian of the first century B. c., mentions such millstones as used in the mines of Egypt to pulverize material which had been previously broken in a mortar. The invention of the arrastra for fine grinding is declared by some authorities to have been made by Bartolomeo de Medina, at Pachuca, Mexico, about A. D. 1557—which is quite probable. Being the first to amalgamate silver on anything like a business scale, he must have felt the necessity for oregrinding apparatus of greater capacity than the old primitive millstones; and the arrastra was thus the natural successor of the millstone. It is very unfortunate that the archives of Pachuca, which has made so much history in ore-treatment, were destroyed in some one of the many insurrections for which, also, the place is renowned. The first application of the stamp to the crushing of rock is asserted by some writers to have been the invention of a Saxon nobleman named Von Maltitz, about the year 1505. Better authenticated reference, however, is made to one Paul Gronstetter, a native of Schwarz, and called an ingenious worker, who, in the year 1519, established at Joachimsthal a process of wet stamping and sifting. Two years later, a larger plant was established at the came place. It is said that he had previously introduced the same device at Schneeberg. How much of the invention was due to Gronstetter is not certain;

Jan 1, 1902

By J Tuma

Technical measurements are an integral part of research and development of new technical devices. Now they are also an integral part of production too, especially as a part of quality control systems. More new problems started with they applications up, like storing and following preservation of big data files. Many problems are also with processing of the measurement results, especially to be up to standards of ISO 9000 normative. It includes basic data about the measurement (structured data) and measurement outputs (huge data streams). Using database systems looks as good idea, because of structured measurement data and they processing. They were developed more concepts of database measurement system support during the research project MSM 272300012. It was decided to develop specialised measurement systems, on the base of experiments and experiences with they use in operating conditions. It proved to be wrong to develop general system, because of compound operating and long response of the system. And it is not possible to use these systems for mass production systems. The problem of data storing is not as easy to be answered, because of dependence on used technical devices. During realisation the measurement system for gearbox noise measurement are data stored to the database, because used analyser system PULSE (Brnel and Kjµr Co) is open structure and can cooperate with other software systems. Anyhow the data streams are not longer (after compression) than the Memo data type, in practical use increases the data file too fast (about hundreds MB daily). Therefore we must include a special supervisory system for administration and creating data files to the system. Nevertheless the used system MS-Access supports data files up to 1 GB, for practical application is better if the file size do not exceed the capacity of CD-ROM disc.

Jan 1, 2003

By J. W. Mahar, E. J. Cording

INTRODUCTION In exploration for rock tunnels, the geology should not only be described, but its effect on excavation and support assessed. It is not an easy task to correlate exploration results with support and excavation requirements, even when the exploration program is detailed and geologic conditions are relatively well known. Many of the significant geologic features are subtle and their effect is difficult to interpret from exploration results. However, in similar geologic settings, there are specific geologic features which will cause recurring support problems. Such features should be actively sought out when exploring in a given geologic setting. In blocky and seamy rock, the primary features controlling performance are the joints, shears, and shear zones. This paper describes the effect of such features on the formation and movement of rock wedges in tunnels driven in foliated metamorphic rocks in Washington, D. C. and New York City. In both areas the foliation commonly forms a N-S striking plane of weakness along which major shear zones, shears, and joints have formed. In addition, the structural history of the two areas has been similar, so that there are similarities in the orientation and character of the other major joint sets and shear zones in the rock mass. The observations were made in tunnels ranging from 10 to 70 ft in width and excavated at depths ranging from 80 to 800 ft. Most of the tunnels described were deep enough to be located in unweathered rock, or in rock only slightly weathered along joints and shears. Variations in the planarity, filling, spacing, and attitude of joints, shears, and shear zones accounted for significant differences in the

Jan 1, 1974

By Nexhmedin Lohja

Macro management of metallurgical industries becomes an important issue in certain situations especially when some government owned metallurgical industries are on the verge or have stopped being feasible. In these cases a government lead macro management in collaboration with domestic institutions and foreign scientific and management expert companies is decisive in order to steer them to a profitable path. This process is not necessary an easy one and incorporates many unknowns and various alternatives. In this paper the macromanagement of the metallurgical industries in Albania will be described as a particular case along with a survey of its mineral deposits, metallurgical facilities and various perspectives for future development. As a country with many mineral resources, the exploration, research, exploitation and processing work of mineral ores before 1990 constituted an important activity of its economy, especially in the exportation of various products of this industry. Since 1990 this activity slowed downs considerably for various reasons and this prompted the necessity of a government lead macromanagement in collaboration with domestic institution and foreign expert companies. This process aims at improving and renewing the technologies in the metallurgical industry in order to transform it into a feasible branch of economy. This goal is being implemented among others through proper geological surveys, rehabilitating and renewing the existing facilities through domestic and foreign investments, the transformation of the ownership or the management from state-owned to local or foreign private companies, etc. Priority is given to the raising of the processing range of the traditional minerals such as chromium, copper, nickel-iron etc. as well as developing new perspective technologies to treat new mineral deposits.

Jan 1, 2006

By F. T. Lee

Directional dependence of strength and deformation properties of the Mount Waldo granite pluton in southeastern Maine is controlled by joints and microfractures whose orientations are linked to flow- induced alignment of microcline crystals. Longitudinal and cross joints which formed during cooling of the mass, as well as much younger sheeting fractures, are commonly associated with subparallel, discontinuous microfractures. The orthogonality of microfractures (open, closed; filled, unfilled; bubble planes) establishes the ease of splitting of the granite. The easiest splitting direction (rift) is subhorizontal, the second easiest direction (grain) is parallel to the cross joints, while the direction of least easy splitting (hardway) is parallel to the longitudinal joints. Static and dynamic measurements made in the field and laboratory established that structural features are responsible for the marked stiffness anisotropy of the granite. In the central part of the pluton the static Young&apos;s modulus in the north-south direction averages 31.1 GPa, and 20.9 GPa in the east-west direction; the stiffer direction being parallel to the long C-axes of microcline phenocrysts and microfractures as identified in outcrop, core samples, and thin sections. Vertical downhole sonic measurements of dynamic moduli ranging from 2.5 to 16.2 GPa appeared to be anomalously low when compared to the static horizontal values. However, the field sonic values were confirmed by laboratory sonic pulse testing of oriented cores. The field results reflected closely spaced layers of open horizontal microfractures. Those deformation and strength properties that are closely tied to bubble planes, filled microfractures, and microcline orientation could be extrapolated to greater depths with good hope of success.

Jan 1, 1984

By W. J. Taylor

FURNACE-MEN who have not taken advantage of the use of dynamite in certain blast-furnace troubles, as explained by Mr. Witherbee in his valuable papers read before the Institute some years since, cannot appreciate the quick relief and great advantage that may be derived at times from its judicious employment. Before giving my experience in the use of high explosives in blastfurnace troubles of certain kinds, I will record a method I have used with marked success in " blowing down." Had I not understood, however, the use of powder, I would have " salamandered " effectually the first time I tried it. Early in my straight-furnace experiments, last summer, at the Chester, N. J., Furnace, I wanted to blow down to within 3 or 4 feet of the tuyeres. To do this with a down-comer not lined, and without putting in any limestone to keep the gases cool enough to do no harm, was not an easy task. We could keep the bell and hopper cool by filling them with water, say 12 inches deep; but before we got the stock down 15 or 20 feet the pyrometer in the gas-flue on top mas up to 1300°, and the clowncomer was red-hot, with the heat still rising. In this emergency my assistant, Mr. N. M. Langdon, urged the trial of a plan lie had often advocated, viz., the introduction of water in some way under the bell in the proper quantity, in order that its evaporation might absorb and reduce the heat of the escaping gases to a point where it would not do any harm. He thought the bell

Jan 1, 1885