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By Jr. Allan

"Although the advantages of large-capacity air receivers for underground mines are plainly evident from published information about various installations in the United States and abroad, details of their construction are not generally known in this country., Ordinary present-day air-compressor installations servicing mining machines are designed to supply air at a specified pressure in sufficient quantity to meet the peak demand of the mine,2/ although this demand may exist for only a few minutes out of 24 hours and, as usually happens, eventually exceeds the capacity of the compressor. Most of the receivers provided with these compressors (to a certain degree of standardi¬zation) are capable of storing a volume of air approximately equal to that compressed in 1 minute by the machine.3, 4/ As a result, during peak-load periods the compressor operates at full load capacity without maintaining kick-off pressure. At other periods of the work cycle, production of compressed air is intermittent.At least one large mine5/ has adopted large-capacity receivers to reduce wear on its air-compressing system caused by the sudden demand of peak loads. Under the old system, the compressors jumped suddenly from half speed to full speed; boilers furnishing steam to the compressors were taxed heavily to provide the increased requirements of power; and machines using the air, among which were four large hoists, were required to operate at 65 pounds per square inch rather than at the 90 pounds per square inch for which the compressors were regulated. Operation of air machines, especially drills, at pressures lower than those for which they were designed decreases their efficiency and increases maintenance costs. In addition, air that comes directly from the compressors has had little opportunity to cool and dry enroute.6./ As a result, quantities of compressor lubricant and water are carried into the machines that use the air. When expansion occurs in the cylinder or turbine of such engines, the temperature of the air drops, and this oil and water is precipitated. The water washes away lubricating oils in the machine, causing poor performance and high cost of maintenance; the compressor oil, in addition to being a poor lubricant for compresed-air engines, exerts a corrosive action on gaskets and rubber hoses.7/Reduction of peak demands on air compressors by large receivers lowers power costs by establishing more nearly constant load factors,8/ and in some cases by permitting the use of smaller compressor capacity.8,9/Load factor is the ratio of average demand to maximum demand; a low load factor costs money.10/Elimination of high-peak demands raises the load factor by making the average and the maximum demand more nearly equal. Further savings may be made possible by large receivers where their use permits charging to be done at night in regions having lower power rates during that period.11/Where ordinary receivers are used, compressor breakdowns cause immediate work stoppages in the mine owing to lack of air. Similarly, the capacity of a large receiver has been known to permit uninterrupted work in the mine until the compressors have been returned to service.9/Large-capacity receivers, either steel-tank or underground rock-chamber, offer a practical solution of many existing problems by providing a sufficient reserve of compressed air within the pressure range required for efficient operation of machines to level off peak demands on the compressor. The com¬pressors operate when the demand has reduced the pressure in the receiver below the regulating pressure and until all air used from the receiver has been replaced. It has been found possible in at least two mines,8.9/ one of which the author has visited, to entirely eliminate one compressor and to obtain more efficient performance from the remaining one by the construction of an underground coal-chamber receiver.8/"

Jan 1, 1950

By Maria I. De Rosa, Charles D. Litton

The National Institute for Occupational Safety and Health (NIOSH/PRL) conducted a series of large-scale experiments to evaluate the effectiveness of optical flame detectors, photoelectric smoke detectors, and combined ionization and photo­electric smoke detectors for rapidly detecting mining equipment cab fires. The detec­tor alarm times were then used to trigger the discharge of a fire inerting system inside the cab to suppress cab material fires. This paper discusses the types of fire detectors tested, the experiments that Were conducted, and the results that were obtained. Con-" elusions are that rapid detection of equipment cab fires can be achieved to trigger the discharge of a fire inerting system inside the cab to protect the operator in the cab.

By Frank E. Cash, Roy G. Stott

This circular describes four modern change houses of the Lake Superior iron - ore district , all conceived and constructed since 1937. The oldest change house described herein was constructed and occupied in 1938 , yet it embodies the modern improvement of air - conditioning . The purpose of this report is to describe and illustrate improvements with regard to health and safety features combined in the construction , arrangement , ventilation , heating ,lighting , and other features , with the aid of photographs , sketches , and diagrams . The modern change house is a fire - resistant structure in which intermingling of men in mine clothes and men in street clothes , hazardous dust , heat and humidity , crowding , poor lighting , slippery and muddy floors , and inadequate facilities for clothes and for bathing have been largely eliminated . The miner coming off shift at a modern mine no longer faces the elements when he gets off the cage . He travels through a tunnel to the change house , where he is cooled gradually by room temperatures as he passes from the mineclothes section and shower room to the street - clothes room . He is assured of dry clothes when he is ready for them . No longer is he sent out of the change house into a muddy yard to drive away as best he can . The modern change house has an improved parking lot and graveled or concreted walkways from it to the change house entrances .

Jan 1, 1949

By J. C. Edwards, C. C. Hwang

In ventilated tunnel fires, smoke and hot combustion products may form a layer near the ceiling and flow in the direction opposite to the ventilation stream. The existence of this reverse stratified flow has an important bearing on fire fighting and evacuation of underground mine roadways, tunnels and building corridors. In the present study, conducted by the National Institute for Occupational Safety and Health, a CFD program (fire dynamics simulator) based on large eddy simulations (LES) is used to model floor-level fires in a ventilated tunnel. Specifically, the critical ventilation velocity that is just sufficient to prevent the formation of a reverse stratified layer is simulated for two tunnels of different size. The computer code is verified by checking the computed velocity profile against experimental measurements. The CFD results show the leveling-off of the critical ventilation velocity as the heat release rate surpasses a certain value. At this critical ventilation, the ceiling temperature above the fire reaches a maximum for both tunnels. The velocity leveling-off can be explained from this observation. An extended correlation of Newman (Combust. Flame 57 (1984) 33) is applied to the temperature profiles obtained by CFD. At the critical ventilation, temperature stratification exists downstream from the fire. The computed critical ventilation velocity shows fair agreement with available experimental data taken from both horizontal and inclined fire tunnels. The CFD simulations indicate that the Froude modeling is an approximation for tunnel fires. The Froude-scaling law does not apply to two geometrically similar fire tunnels. The CFD results are compared with two simple theories of critical ventilation by Kennedy et al. (ASHRAE Trans. Res. 102(2) (1996) 40) and Kunsch

By Edward P. Barrett

The production of sponge iron is one of the earliest arts in the metal¬lurgy of iron and steel. The idea of producing iron direct from ore at temperatures lower than the melting point of, the iron has persisted throughout the centuries. The purpose of this paper is to present a general picture of the methods, proposed or tried within the past 100 years, for producing sponge iron by treating hot ore with heated reducing gases. The abundant literature has been abstracted, and quoted freely. Publications concerning more detailed information on the various methods are referred to in the footnotes and in the bibliography.

Jan 1, 1949

By Carl R. Peterson

This report describes the development and testing of a prototype tunneling machine. Principal efforts were aimed at testing of the fragmentation subsystem of a continuous drill and blast hard rock excavation machine suitable for use in underground mining and tunneling applications. The concept utilizes a unique self -shielding spiral blasting pattern that permits efficient performance with relatively small single shots, while at the same time directing major blast fragments at right angles to the tunnel axis. A major accomplishement was the development of a remote controlled, loading and initiation system in which explosive slurry and a detonator are Simultaneously placed (pumped) into the blasthole via a loading hose. The special electric long-delay detonator is inductively ignited upon emplacement, and the machine remains at the face during the blast.

Jan 1, 1976

By David R. Wilburn

The U.S. Bureau of Mines investigated the resources, costs, capacities, market relationships, and short-and long-term supply of bauxite, alumina, and aluminum. The 45 evaluated mines and deposits in 14 market economy countries (MEC's) have a demonstrated resource of 8.4 billion mt of bauxite and an aluminum content of approximately 2.1 billion mt. Developed world bauxite resources and existing primary aluminum smelting and refining capacity are sufficient to satisfy demand through at least 1995, when additional properties (with higher cost levels) would need to be developed to satisfy future demand levels. It is anticipated that new alumina or aluminum production most likely would occur in developing regions with large bauxite potential, low-cost energy sources, and a close proximity to refining and/or smelting capacity. An increase in aluminum recycling capacity would help meet future demand increases. A series of network model supply analyses was performed for the period 1988 through 2000. Based on announced future production levels and assuming demand grows at the level outlined in the analyses, model results indicate there is sufficient material available to meet demand until 1998, where-upon an aluminum shortfall is projected. Additional analyses investigated the effect of a reduced growth rate of demand and regional production variations in Venezuela on the international aluminum industry.

Jan 1, 1993

By Joseph J. Wallace, William H. Tavenner, D. A. Reynolds, John M. Provost, James J. Dowd, R. F. Abemethy

"CONCLUSIONSThe investigation shows that there are 5 coal beds of major importance in Wyoming County from the standpoint of present production - Pocahontas No. 3, No. 2 Gas, Sewell, Beckley, and Eagle - and 5 beds of minor importance - Pocahontas No. 6, Cedar Grove, Winifrede, Douglas, and Chilton. The Pocahontas No. 3 bed contains the largest remaining known reserves.Known measured and indicated reserves in all beds, based on a minimum thick¬ness of 14 inches and on 1,800 tons per acre-foot of coal in place, are estimated at 2,665 million short tons as of January 1, 1951. Of this total, 2,121 million short tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.Recoverable reserves of coal have been estimated in beds 28 inches and more thick. This thickness is about the minimum now being mined by hand loading onto conveyors in the Appalachian region. The weighted average recovery for all beds in Wyoming County, as determined by this investigation, is 55.0 percent. This percent¬age is based on the total thickness of coal (less partings 3/8 inch or more thick) in the bed rather than on the thickness of the coal mined. The known recoverable reserves are estimated to be 1,167 million tons as of January 1, 1951.4. Since most of the Wyoming coals are medium- and low-volatile bituminous in rank and expand during carbonization in modern ovens, they are blended with high-volatile contracting coals."

Apr 1, 1953

By Walter D. Holland

This is one of a series of instruction guides developed to help instructors present health and safety training courses to workers in the coal mining industry. This course is intended for training those, usually the safety officers, who perform surveys fur inhalation contaminants in above ground work areas. The handbook entitled ?Handbook for Surveys of Inhalation Contaminants in Above Ground Coal Mining and Processing Work Areas? (NTIS #PB-243-35";) is used as a manual for the course and as a prime reference when performing the actual surveys or interpreting the sampling results. There are six experiments for the students to perform during the course to familiarize them with the sampling devices routinely used during the surveys.

Jan 1, 1976

By Keith G. Wallace

Coal mine ventilation systems are often subject to high leakage rates. As a result, changes in airflow resistance will strongly affect the efficiency with which air is delivered to the working place. One major source of airflow resistance is the line brattice used to direct air from the last open crosscut to the working face. Because it is a great distance from the fan, the resistance of the line brattice can result in more overall leakage than an equivalent resistance closer to the fan. Substituting auxiliary fans for brattice eliminates this source of resistance, with improvements in system efficiency and cost. Also, in some mines, the leakage that leads to spontaneous combustion can be reduced. The benefits obtained by several different brattice and fan substitutions have been studied by Mine Ventilation Services, Inc., Lafayette, CA, under contract to the U.S. Bureau of Mines. Changes in main fan duty were compared with additional costs associated with auxiliary fans. Results indicate that in some circumstances, considerable leakage reductions and cost savings are possible.

Jan 1, 1990

By T. W. Johnson

The United States Bureau of Mines, in cooperation with the Natural Gas Department of the American Gas Association, has been studying actively for the past several years the flow of natural gas through high-pressure pipe lines. This report deals with that part of the study involving the design off pipe-line systems consisting of lines laid parallel to each other. The lines are referred to as the original line and the parallel line. The paralleling line may or may not extend the entire length of the original line; however, the parallel line is connected at its two ends to the original line. As a result of the large expansion of the natural-gas industry almost all markets within economic distance from the developed gas fields have at least one pipe line supplying them with natural gas. Small increases in the consumers' demand for natural gas can be met usually by increasing operating pressures, but any marked increase in demand necessitates paralleling sections of the existing systems. It is believed that to a large extent future

Jan 1, 1934

By Parry. V. F., John B. Goodman

"INTRODUCTION The Denver region coal field, covering an area of approximately 7,640 square miles, extends from the Wyoming State line to the middle of El Paso County, Colo. The coal in this region is subbituminous in rank. Much of it is used as domestic fuel. During the last decade the production of coal in this field has remained fairly constant at an average of 2,600,000 tons per year. This production has come from 50 to 60 mines, 88 to 90 percent of the production being from the section of the field north of Denver.According to the Standard Specifications for Classification of Coal by Bank of the American Society for Testing Materials 4/ the coals in this region are classified in the Subbituminous B and C group. On the as—mined basis, they contain about 22 percent moisture and average 9,600 B.t.u. per pound. They are noncoking and slack to a variable extent when exposed to the weather. This is characteristic of subbituminous coals."

Aug 1, 1939

By G. L. Oldright

The first Report of Investigations of the present series (No. 4562) was on the fundamental properties of lead compounds, and the manner in which they set limits to the richness of lead products treated in the usual sintering-blast furnace units. These properties of the compounds were emphasized, as' it was desired, also, to learn the limitations of smelting the same compounds in present ore hearth practice; the hearth has a competitor in these "usual" units, even with the rich lead feeds best adapted for the hearths. Operating conditions that were followed in older metallurgical processes, when rich products, were treated, were outlined. The second report of the series (R. I. 4563) was on the development of the ore hearths of the types now used in the Tri-State from the viewpoint of the features, functions, and dimensions of the earlier hearths that had been most changed. Experimental data, for both well and poorly desulfurized charges being considered, were given to show the relative changes in the sizes and compositions of the charges after they were added to the ore (Scotch) hearths. A general picture was given of the charge column and of the conditions prevailing there when the operation was satisfactory. In this third paper, the composition of the gases prevailing in the charge column at various elevations will be correlated with what has been learned of the nature of the charge column in order to trace the steps of operation by which lead sulfide is converted into metallic lead. The metallurgical factors that govern operation and the lines along which improvements may be made will be noted.

Jan 1, 1949

By R. Hogg, T. H. Dumm

"The mathematical treatments used in the evaluation of particle size distribution from pipet-withdrawal centrifuge data are reviewed. An error in the published procedure for multiple-sample withdrawal systems is pointed out and a corrected formulation is presented. An alternative treatment, based on a piece-wise linearization of the size distribution is described. Computer simulations of the analytical and data evaluation procedures indicate that the errors in the original formulation are not generally serious and that the corrected and alternative procedures lead to very similar estimates. Except for some cases involving very narrow size distributions, the alternative approach appears to give slightly closer estimates of the size distribution. Comparisons based on actual experimental data are also described.1 IntroductionSedimentation methods are widely used for the determination of particle size distributions. The procedures are relatively simple to use and the results are essentially absolute, requiring no external calibration. Gravity sedimentation is typically applicable to particles in the size range of about I to 50 pm and generally involves measurement of the relative concentration of particles as a function of depth and time in a dilute suspension. Particle size is calculated using Stokes, law:"

Mar 1, 1989

By John P. Powell

The increasing demands for petroleum and its products and the steadily increasing cost of discovering and developing new oil fields are factors that emphasize the importance of increasing the recovery of oil from known petroleum reserves. Water flooding is a valuable conservation measure, not only preventing premature abandonment of stripper leases but also reviving interest in many areas previously abandoned. The use of water flooding as a means for recovering additional oil from partly depleted oil-bearing formations was first tried in Oklahoma in 1931. Early water-flooding operations were confined to the area of shallow Bartlesville-sand formations in Nowata and Rogers Counties, where many of the projects were outstandingly successful. The results of these operations stimulated activities in other pools in Oklahoma, and by the end of 1949 water flooding had been tried in 25 of the 49 oil-producing counties in the State (fig. 1). Approximately 33 million barrels of oil, or 1,806 barrels per acre, had been recovered by December 31, 1949, from 18,221 productive acres included in the 162 active and abandoned projects in Oklahoma by injection of approximately 449 million barrels of water.

Jan 1, 1952

By R. A. Cattell

With the activities of the Petroleum and Natural Gas Division geared chiefly to problems directly connected with the war effort , the emphasis of the work under oil and gas development and production was to make engineering studies of selected reservoirs for the Petroleum Administration for War , to determine the extractable quantities of components in them, and to study the characteristics of these components for use in the manufacture of aviation gasoline and other products . The needs of the Petroleum Administration for War and the operators for specific data from gas - condensate fields were fulfilled , and , in addition , engineering data along lines of a forward - looking program of research on reservoir behavior were collected , which should be of great value in the postwar period . It is planned to publish many of these data as soon as conditions permit . The work of the Secondary Recovery Section had as its objectives in- . creasing the rate of production of crude petroleum and , which is more important , preventing the premature abandonment of wells in " stripper " and marginal According to the National Survey of Stripper Wells by the National Stripper Well Association in cooperation with the Interstate Oil Compact Commission , a total of 67,460 stripper wells was abandoned from January 1 , 1935 , to July 1 , 1942 , inclusive , with an estimated loss in proved reserves of approximately 216 million barrels . This survey also indicates that over 1.2 billion barrels of oil would be recovered by primary production from more than 290,000 stripper wells then in operation , and an additional 2.5 billion barrels of oil could be recovered from them by secondary production methods . The work of the Chemistry and Refining Section was oriented towards the optimum utilization of crude oils in the manufacture of aviation fuels for spark-ignition and jet - propulsion engines . The work involved intensive studies of superfractionation , hydrocarbon analysis , and the engine testing of fuels . Particular attention was given to the effect of sulfur compounds in the crude oils and in the fuels made from them . The research on thermodynamics is concerned with the experimental determination of precise and accurate values of the fundamental thermodynamic constants of pure hydrocarbons and related compounds . The data obtained in these investigations will be utilized for devising and improving chemical processes in which petroleum hydrocarbons are the raw materials . Without such data , much time and expensive material and equipment may be wasted in attempts to obtain reactions under conditions that the laws of thermodynamics rule out of consideration . Thermodynamic data are useful and required in the petroleum industry for calculations of heat balances in the design of furnaces , fractionating towers , and heat- transfer equipment . It is of utmost importance , also , to know the heat requirements of cracking and other chemical reactions so that heat may be supplied or dissipated in the proper proportions . These needs for thermodynamic data are being recognized more and more by petroleum -refining engineers . The responsibility for the production of helium for the Navy , the Army , other governmental agencies and non-Federal users is vested in the Bureau of Mines by an Act of Congress ( 50 Stat . 885 ; 50 U.S.c. 161-166 ) . The Helium Subdivision of the Petroleum and Natural Gas Division continued to meet all demands for helium .

Jun 1, 1949

By Jerry E. Olson

In 1986, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied part of the 20,071-acre South Fork Wilderness Study Area (OR-005-033) and part of the 8,791-acre Sand Hollow Wilderness Study Area (OR-005-034) in order to evaluate their identified mineral resources. The study areas are located in Crook County, OR, about 58 air miles east from Bend. The areas studied are underlain by Tertiary- and Quaternary-age volcanic and tuffaceous sedimentary rocks. No mineral resources were identified in or adjacent to the study area. Except for common opal and agate occurrences along the northern boundary of the study areas, no mines, prospects, or mineralized zones occur within the study areas. Bentonite is periodically mined less than 1 mi southwest of the Sand Hollow study area boundary. Neither of the study areas has geothermal leases, but both areas are under lease for oil and gas.

Jan 1, 1987

By Halagowder Devaraj, Mostafa Sheykhnazari, Veer P. Bhavanandan

"A sensitive colorimetric assay for detecting mucins and glycoproteins rich in 0-glycosidically linked saccharides is reported. The method combines the susceptibility of N-acetylgalactosamine terminating 0-glyco idically linked saccharides to P-elimination with the Morgan-Elson reaction for N-acetylhexosamines with free reducing ends. All mucin and mucin-type glycoproteins but none of the serum-type glycoproteins tested resulted in characteristic color production. All mucins tested gave linear responses in the range 5 to 200 ""g and the assay was also adapted to the microscale involving the use of 96-well microtiter plates. The microassay in which the volumes of samples and reagents are scaled down 2.5-fold was particularly useful in monitoring of mucins, in the presence of other glycoconjugates, in large numbers of samples obtained during fractionation procedures. Cesium chloride, cesium bromide, potassium thiocyanate, and various detergents do not interfere with the colorimetric determination. Guanidine hydrochloride, cesium triftuoroacetate, and B-mercap- . toethanol decreased color by 30 to 45%; however, the interference was not serious to prevent the use of the method for detection of mucins in their presence. The use of the method for the specific detection of mucin during fractionation by gel filtration and density gradient centrifugation of cystic fibrosis sputum samples is demonstrated. Mucins are an important class of biomacromolecules whose structure-function relationship is poorly understood (1,2). The investigations of mucins are hampered by difficulties in purifying these very large size molecules which appear to avidly bind other components of the mucus (3,4). One of the problems during purification is the specific detection of mucins. For example, during the various purification steps, the fractions containing mucins are typically detected by assaying for neutral sugars (hexoses) (5,6), for sialic acids (7), or for periodate oxidizable saccharide units (8). However, these methods are not entirely satisfactory because neutral sugars, sialic acids, and periodate-oxidizable saccharides are also components of other glycoconjugates. In addition, the neutral sugar and sialic acid measurements are also subject to interference from high levels of proteins and nucleic acids."

Jan 1, 1990

By Paul Zinner

Efforts to win an enriched manganiferous product from the Missouri Valley deposits of South Dakota have included an application of most known ore-dressing devices and have been largely unsuccessful. At least two methods showed some promise of success and were the subjects of detailed Investigation by the Bureau of Mines during the period from July 1945 to August 1947. A series of mining and beneficiation tests were undertaken to determine conditions under which the most feasible concentration methods could be employed and to define the limits of such applications in terms of the character of the final beneficiated product. In the absence of a significant current market for any conceivable product of beneficiation, the extent to which applied methods might be considered successful was measured in terms of ratios of recoveries to grade, regardless of the adaptability of such beneficiated products to further metallurgical or direct usage. The results of all investigations show that production of a shale-free, concretionary, manganese-bearing product by any known method requires great sacrifices in manganese recovery. Products of beneficiation, with specifications permitting some inclusion of shale, can probably be most effectively produced by methods employing specialized jigging equipment as the principal functional unit of a process.

Jan 1, 1949

By Aner W. Erickson

"Preliminary examination of tungsten deposits on the Mountain View property near Hyder, Alaska, was made by Neal M. Muir, an engineer of the Bureau of Mines daring the summer of 1942. Fifteen samples were cut, rough esti¬mates of ore reserves were made, and it was proposed to extend the drift on scheelite-bearing vein 300 feet in a northwesterly direction.From May 22 to October 24, 1944, an exploratory project was conducted on the property by the Bureau. In the course of this work, the camp buildings were rehabilitated; the dam, hydraulic line, and machinery were repaired; 226 feet of drift was driven; 80 groove samples aggregating 3.9 tons in weight were cut; a 6,000-foot surface and underground traverse was run; and the area was mapped in detail.In its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to the national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director.Special acknowledgment is doe Neal W. Muir, project engineer, and Robert S. Sanford, acting chief, Alaska Division, Mining Branch, for their supervision of the field work and revision of the report.Acknowledgment is also made to Silbak Premier, Ltd., for rendering valuable assistance in the repair of equipment and for extending various courtesies to Bureau of Mines personnel during the conduct of this project.The Mountain View property is located at latitude 55° 59' north, and longitude 130° 03' west in the Salmon River mining district of southeastern Alaska, about 5 miles in a northwesterly direction from the town of Hyder, which lies at the head of Portland Canal, as shown in figures 1 and 2. Vein outcrops and surface workings are at an elevation of 950 feet and occupy the west flank of a low ridge between Skookum and Fish Creeks, as shown in figure 3. The portal of the long adit exposing the vein at depth is on Skookum Creek about 550 feet north of the confluence of Skookum and Fish Creeks.Access to the property is over a 4-foot wide trail built and maintained by the United States Forest Service. This trail is suitable for pack animals and is adequate for transportation of supplies and material for exploratory work. During the periods of camp construction and past exploratory operations a 4,000-foot, single-cable, aerial tramway, now in disrepair, served for transportation of materials and all machinery from the Salmon River Highway to the property. The cost of such hauling was high, amounting to $12 a ton. Topography is suitable for construction of a ""cat road"" 2 miles in length, connecting the property with the Salmon River Highway. It is estimated that such a road could be built for $5,000 a mile, and supplies, machinery, and concentrates could be haled over it at a cost of less than $2.50 a ton."

Sep 1, 1946