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By P Ritchie, E H. Briese, N A. Currey

Kidston Gold Mines, located in semi-arid North Queensland, Australia is currently in its closure phase. Highly innovative and comprehensive rehabilitation strategies were employed at the site, including the direct revegetation of the surface of the tailings storage; the construction of a tailings sediment entrapment pond; the construction of a spillway to drain large rainfall events from the surface of the tailings; the construction of store/release covers over the tops of the waste rock dumps; the sheeting with oxide waste rock of the waste rock dump slopes; the partial back-filling of the initial Wises Hill Pit with waste rock and thickened tailings produced from the subsequent Eldridge Pit; the partial flooding of Eldridge Pit following the end of mining; and the construction of wetland systems to treat contaminated tailings and waste rock dump seepage. These closure strategies involved the careful consideration of water management. Specific water management issues included understanding the water balance of the tailings dam; the operation of the tailings dam sediment entrapment pond and spillway; understanding the water balance of the store/release waste rock dump covers; the importance and sustainability of vegetation on the tailings, store/release waste rock dump covers, and on the sheeted waste rock dump slopes; the level and quality of water in the partially flooded Eldridge Pit; and the treatment of contaminated seepage in the constructed wetlands. The seasonal and highly variable rainfall experienced in this semi-arid climate posed a number of challenges for the management of water on the site post-closure. The paper details these challenges and highlights how they were resolved over the period leading up to and following the end of mining.

Jan 1, 2003

By Arash Maghsoudloo, Asli Can

"Abstract This paper presents a ground improvement implementation case under a raft foundation of a local hospital. The selected ground improvement method is Wet Soil Mixing (WSM) technique. Soil mixing is increasingly applied to environmental applications and ground stabilization in geotechnical projects. In this technique, weak soil is mixed with cementitious slurry to improve the characteristics of the soil. The investigated case is one of the pioneering WSM ground improvement technique implementation cases in Turkey. The soil profile is mainly consisted of low plasticity clay. The effect of ground improvement is verified by a series of laboratory tests and four in-situ pile loading tests. The results of in-situ pile load tests on constructed soilcrete columns showed an acceptable factor of safety for the bearing capacity of the WSM columns. Measured bearing capacities in all four tested columns were nearly 20% higher than calculated values. In addition, a set of samples are obtained from the constructed columns and unconfined compression tests have been conducted. The laboratory test results indicate that the selected cementitious slurry has a sufficient efficiency to form the stabilizing columns.IntroductionIn the construction industry, stabilization of the soft ground by lime or cement stabilization is a widely used technique. In ground improvement systems deep mixing method (DMM) results in the same stabilization in deep portions of the soft soil profile by mixing cementitious slurry by means of mechanical augers. The pioneering cases of modern deep mixing application can be traced back to the year 1970 that was used for the stabilization of marine soils below the water level for the construction of harbor structures (Terashi et al., 1979). Nowadays, DMM is shown to be a proper and efficient method for the foundation of the structures and embankments on land. Some recent studies also reported that reasonable settlement reduction range in the stabilized soils under the foundation of structures (Archeewa et al., 2011). In addition to reduction of the structural settlement under service loads, deep mixing methods are also utilized when there is a concern with contaminated soil and groundwater or groundwater control (Andromalos and Bahner, 2003).Although, the DMM is shown to be a successful method in numerous studies for improvement of a wide range of soil types such as organics, fine-grained, and coarse grained material, it has some limitations (Archeewa et al. 2011, Jameson et al. 2010, Jelisic and Leppanen 2004, Lambrechts and Roy 1997, Meyersohn 2007, Miki and Nozu 2004, Olsson et al. 2008, O’Rourke and McGinn 2004, Stewart et al. 2004, Yang et al. 2011). High soil density and stiffness could damage deep mixing rigs. Engineering properties of the soilcrete columns changes based on the soil type, water content and other factors such as organic content of the available soil profile, so properties of the generated soilcrete should be verified by a set of rigorous testing procedures (Puppala et al. 2004).Based on the general classifications presented in the ground improvement literature, deep soil mixing method is divided into two main types of dry or wet mixing methods. In the dry and mixing methods compressed air and water are utilized as the binder transporter medium respectively (Moseley and Krisch, 2004). In addition, DMM methods can be categorized based on the employed mixing methods during the construction. In this study, the main aim is to present and elaborate on the selected method is known as Wet Speed Soil Mixing (WSSM)."

Jan 1, 2014

By Robert G. Gibson, Joel D. Gibbons

Measurements and analyses were conducted of whole-body vibration aboard seven commercially available passenger and/or recreational vehicles: sedan; sport-utility vehicle (SUV); pickup truck; moving truck; motorcycle; all-terrain vehicle (ATV); and boat. The purpose of the testing was to measure and assess whole-body vibration exposure in a range of typical vehicle environments in order to gain understanding of typical exposure levels characteristic of activities of daily living. Vehicle models tested (and model year) were: Ford Taurus (1995); Jeep Cherokee Sport (2000); Toyota Tundra SR5 (2002); Ford F-350 (1997); Harley-Davidson Electra Glide Classic (2004); Yamaha Kodiak 400 4x4; and Steiger Craft Model 21 Montauk. All vehicles were tested with their standard factory-installed seats and were operated under a range of normal operating conditions and speeds typical of intended vehicle use. Methods The measurement, processing, analysis, and exposure assessment methods follow the guidance of generally accepted, national and international consensus standards relevant to the evaluation of whole-body vibration, including ISO 2631-1 [1] and ANSI S3.18 [2]. Seats were instrumented with low-mass triaxial accelerometers mounted in seat pads. Accelerometers used in the test are specified to have flat frequency response over the frequency range of 0.5 to 80 Hz, and all accelerometers were recently calibrated traceable to the National Institute of Standards and Technology (NIST). Seat pads were installed following guidance in the relevant standards [1, 2], with sensitive axes of the accelerometers following the standard coordinate system with respect to the seated occupant. (The x-axis represents fore-aft motion; the y-axis represents side-to-side motion; and the z-axis represents vertical motion with respect to the occupant.) Vibration data processing and analysis, including filtering, sampling, frequency-weighting, averaging, summation, and determination of basic and additional metrics followed procedures in the relevant standards [1, 2]. Digitized time series data were acquired and stored using a PC-based data acquisition system. Whole-body vibration exposure analyses were conducted via post-processing. During data processing, recorded periods of seat acceleration that were identified and verified as resulting from occupant-induced motion rather than vehicle motion were excluded prior to exposure analysis. The basic evaluation metric for whole-body vibration is the frequency-weighted root-mean-square (r.m.s.) acceleration, aw. The primary additional evaluation metric is the fourth-power

Jan 6, 2006

By Jayagopal Ucbil, M. Krishna, V. T. Vijayalakshmi

"The pitting susceptibility of aluminium metal matrix composites reinforced with garnet particles has been examined using static weight loss method by exposing the metal matrix composites (MMC) specimens to the action of IN HCI acid at laboratory temperature for different time intervals. It was found that the corrosion rate decreased with increase in weight percentage of reinforcement while the corrosion rate was a function of the matrix alloy but not of the reinforcement material. Further, it was found that the rate of corrosion was dependent on the interface region formed between the reinforcement and the matrix. A comparison of the base matrix with the corresponding composite when subjected to heat treatment for varying periods of 4, 8, and 12 hours respectively was made. The comparison revealed that corrosion resistance of the composite increased with the duration of heat treatment and this has established a considerable improvement in corrosion resistance of the composite when compared with the base matrix.IntroductionMetal matrix composites (MMCs) offer designers many added benefits, as they are particularly suited for applications requiring good strength at high temperature, good structural rigidity, dimensional stability, and light weight [1-5]. The trend is towards safe usage of the MMC parts in the automobile engine, which work particularly at high temperature and pressure environments [6-7]. Particles reinforced MMCs have been most popular over the last two decades. Among the MMCs, the most popular families are represented by aluminium reinforced with ceramic particles. Although the incorporation of the second phase into a matrix material can enhance the physical and mechanical properties of the base metal, it could also significantly change the corrosion behavior."

Jan 1, 2000

The case study has identified and characterised additional subsidence arising from longwall mining above or under existing longwall goaf. It suggests that the magnitude, mechanisms and prediction methods for such additional subsidence are different between the two mining configurations. This paper presents a proposed method to predict maximum vertical subsidence due to longwall mining under existing longwall goaf. It suggests that, unless different results from further new cases become available, the findings presented in this article, including the aforementioned prediction method, be applicable to the majority of sites in New South Wales, where multi-seam longwall mining is to take place. This article also presents an important concept of 'overburden modification' due to multi-seam mining. A causal relationship between the above-mentioned additional subsidence and 'overburden modification' has been identified as a result of the case studies. Further investigations into the physical processes that cause such overburden modification will be fundamental to the understanding and management of multi-seam subsidence.

Nov 25, 2010

By R. C. D. Phillis

Conventional stoping in hard rock mining is largely considered an operational environment. This paper suggests that stoping falls within the realm of a project management environment typified by uncertainty, variation, and large numbers of interdependencies. Stoping was then equated to a micro-project with many simultaneous activities that had to be executed accurately using finite resources within limited shift durations in order to reach specific goals. Critical chain project management (CCPM) principles were applied to the stoping activities, and the results showed that the number of blasts per panel can be significantly increased by successfully moving the distribution of work as close as possible to the start of shift. Critical chain principles also assisted in facilitating re-focusing and teamwork among stoping crews as well as between day- and night-shift crews. The main recorded success was in managing inherent protective capacities/local contingencies/fat/buffers that are found in all projects. The impact on mine health and safety (MHS) was significant as individual operators and crews became convinced that they could perform all stoping tasks (activities) without compromising accuracy or speed.

Jan 1, 2011

By M Brockman, M Cowan, A Robeson

"Sunrise Dam Gold Mine (SDGM) is located 820 km from Perth, 220 km from Kalgoorlie—Boulder and 55 km south of Laverton in Western Australia. The SDGM main pit had successfully operated since 1997 and was due to be completed during 2012. An opportunity existed to extract the high-grade crown pillar – 600 kt @ 7 g/t for 135 koz by either open pit or underground methods.The crown pillar was the 60 m (vertically) thick remaining part of the high-grade Cosmo orebody between the top of the paste filled underground mine stopes and the planned base of the final open pit shell.There were two major difficulties being considered when choosing the underground or open pit options:a major wall failure in the upper section of the main pit wall directly above the crown pillar restricting access from the base of the open pit to the top of the crown pillarimpact of a high rainfall event while the crown pillar was being mined from either surface or underground resulting in flooding of the underground mine workings.This paper will discuss the following issues:the process to identify and evaluate the risks in both options using knowledge based modelling software; this technique allowed the evaluation of a complex set of assumptions to arrive at the preferred optionremediation of the Watu failurethe selection of the preferred option and the challenges encountered before, during and after the extraction of the crown pillarthe planning and geotechnical work to ensure the safe extraction of the crown pillarsuccessful outcomes transitioning from open pit operation to a solely underground operation.Citation:Robeson, A, Cowan, M and Brockman, M, 2016. A Case Study on the Assessment, Planning and Extraction of the Crown Pillar at Sunrise Dam Gold Mine, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 115–136 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By Stefan Larsson, Sebastian Adevik, Sadek Baker, Razvan Ignat

"Abstract Uncertain strength, deformation and flow properties in dry deep mixing columns often lead to conservative choices concerning design values where the design is regularly complemented with a surcharge fill. The surcharge not only leads to increased cost but also to logistical problems where the surcharge is a physical obstacle. The deformation properties of a ground improvement were studied by means of two small embankment load tests. The settlement measurements were also used in FEM analyses, where the effect of surcharge on creep settlements was investigated. Based on the results, the effects of the surcharge were considered negligible and could safely be ignored. The project is an example how the contractor can use a field test as an effective design approach.IntroductionGround improvement of soft soils with dry deep mixing columns, or lime-cement columns, is often combined with a surcharge fill. The main reason for using a surcharge is to force the primary settlement and some of the secondary settlement that would have occurred under the final embankment height alone, to take place under the surcharge loading. Another reason is to level out uneven settlements. Strength and deformation properties in improved soil cannot be sufficiently assessed in advance, before columns have been tested on-site, and this uncertainty often lead to conservative choices concerning design values. In order to compensate for a slow forecasted consolidation process, the design is regularly complemented with a surcharge. The surcharge not only leads to increased cost but also to logistical problems where the surcharge is a physical obstacle.Extensive research undertaken by Åhnberg (2006, 2007) shows, by means of triaxial and oedometer tests, that cementation processes and a load acting on the columns during hardening, makes the improved soil to behave as a heavily over-consolidated soil due to an increase in quasi pre-consolidation pressure. The effects of using a surcharge on the time for consolidation and creep properties are thus probably small, since the stress level does not normally exceed this quasi pre-consolidation pressure. A study presented by Venda Oliveira et al. (2013) shows that the stress level within small ranges has limited effect on the creep properties.This paper presents a case study where the deformation properties of a ground improvement using dry deep mixing columns was investigated by load tests on two small test embankments. The tests were performed at the Interchange Värtan project site, which is part of the Norra länken infrastructure project in Stockholm. The tests were not performed as a research project but simple load tests performed by the contractor with the purpose of rationalizing the design delivered by the client. One purpose of the load tests was to assess the deformations when the columns are loaded temporarily by overlaying concrete works. Another purpose was to provide some input data to a study of the effects of using surcharge on creep settlements. The analysis was conducted as finite element modeling using the commercial code PLAXIS, where creep settlements can be simulated using the built-in Soft Soil Creep model."

Jan 1, 2014

By A A. Ndiaye, A Galli

In a companion paper on current hedging practices in the mining industry (Armstrong et al, 2009) we showed that contrary to popular belief, mining groups are still using financial derivatives to hedge against foreign exchange risk and interest rate risk, and more recently against adverse changes in energy prices, notably the oil price. This paper presents a case study on a hypothetical gold mine to illustrate the impact that hedging policies could have on its profitability by reducing the downside risk due to adverse changes in the exchange rate and increases in fuel prices. The characteristics of the hypothetical mine have been set to reproduce those of a real gold deposit, the Kisladag mine that is currently being exploited by open pit methods in Turkey. This mine was selected because its feasibility study was available to the public. Geostatistical simulations are used to reproduce the inherent uncertainty on the recoverable reserves û stochastic simulations are used to generate the variability of the other three key sources of uncertainty: the gold price, the cost of energy and the exchange rate. A simple strategy based on straightforward vanilla options (puts and calls) was developed for hedging the last two risks, on the assumption that the company sells its production at the prevailing spot price.

Jan 1, 2009

By Gift Chisakuta, Bravo Mbao, Nils Schwarz, Angus Feather, Anthony Mukutuma

Bwana Mkubwa is a 50 000 tons per annum copper cathode producer, owned by First Quantum Minerals and located in Ndola, on the Zambian Copperbelt. The Bwana Mkubwa solvent-extraction circuit was started up in 1997. In 2002, the plant began treating ore from First Quantum?s Lonshi mine located in the Democratic Republic of Congo. The Lonshi ore is exceptionally fine and the amount of solids in the feed solution reporting to the solvent-extraction feed solution increased dramatically. Initially, crud was filtered in a filter press, but this rapidly blinded and seldom produced anything better than a wet sludge containing large quantities of organic. In December 2003 the decision was made to install a Flottweg Z4E-3/441 Tricanter® centrifuge to recover organic from the crud. The installation was completed in June 2004 and has since led to significant improvements in plant operability and savings in organic consumption.

Jan 1, 2007

Robe River Mining manages a large open pit iron ore mine in the Pilbara region of the North-West of Australia. The mine is managed for various joint venture participants.In July 1986, Robe River Mining made various changes to its management philosophy, which were heavily publicised in the media at the time.As a result of those changes to its management philosophy, Robe River Mining has been able to dramatically increase its production output, productivity, and safety performance without having to resort to major capital outlays and without the benefit of restructuring of applicable industrial awards.

Jan 1, 1992

By Rajesh Minda

160 numbers of double bulb underreamed piles were constructed based on the safe loads specified in IS code at Tripura. The pile load tests yielded a much lower capacity. A detailed investigation work was carried out to find out the reasons for anomaly. The work included soil exploration followed by extraction of two piles bearing numbers 72 and 151. It was seen that the bulbs were not formed as per specification. Some comments on IS Code have been made at the end.

Jan 1, 1996

By Franklin M. Grynkewicz

The subject of bearing pile performance installed by vibratory hammers has been a matter of increasing study and continued controversy. A recent case study from a major bridge replacement project is discussed which provides encouraging data on the use of vibratory pile hammers as a primary means of pile installation and also presents the problems associated with its general acceptance. The bridge project case study foundations consisted of HP 14 x 89 pile sections, designed to develop capacity primarily in friction. Preliminary tip elevations were determined by traditional static analyses. Production pile installation was performed using an IHC S-70 Hydro-Hammer. Driving criteria and final production pile tip elevations were determined after preliminary indicator pile drive tests and static load test results at bridge pier cofferdam locations. Based on impact driven production pile performance, the Contractor wished to investigate vibratory driven piles as a means to accelerate construction schedule. Dynamic pile testing procedures were used as the primary measurement tool and test results were compared to the production pile drive records and prior static load tests. Field testing consisted of driving and monitoring with the PDA impact driven piles to the design tip elevation. Three vibratory driven piles were installed to the same tip elevation and immediately subjected to impact driving and dynamic testing to compare dynamic pile resistance. The results indicated that the site soil conditions were favorable for vibratory pile hammer installation. Recommendations and procedures for proceeding with vibratory hammer pile installation were presented to the Owner. These procedures included quality control in conformance with latest AASHTO recommendations. The Owner, in spite of the site specific data base and QA/QC procedures, would not accept vibratory pile hammer installation, due to the absence of precedence. It is concluded that for vibratory methods to become accepted a rational method of analysis, design and field QA/QC procedures requires development. In addition, the engineering community and Owners/Agencies must be more open to alternate methods of foundation construction. The continued development of dynamic methods of monitoring vibratory pile installation is considered to be key to the general acceptance of this installation procedure.

Jan 1, 1991

By Yongsik Jeong, Kwangmin Kim

Most tailings storage facility (TSF) failures occur in active, upstream-type TSFs, often due to extreme and unexpected weather conditions—specifically, heavy rainfall and strong winds. This case study of a TSF in southern Arizona examines the use of the optimum safe beach distance (Doptimal, the optimum distance between the crest and decant pond) as a tool for monitoring geotechnical stability and reducing catastrophic failures. A digital model of the TSF was used to determine the critical beach distance (Dcritical) under normal weather conditions, and Doptimal was then determined by adding incremental distances to account for the effects of heavy rainfall (Drainfall) and strong winds (Dwind). To overcome accessibility issues, a drone was used to map the TSF geometry and create a digital model. This model served as the basis for conducting a coupled stress-seepage, finite-element (FEM) analysis with a safety factor of 2.0 to assess geotechnical stability (Dcritical). The safe beach distance increments were determined using the PMP (probable maximum precipitation) and possible maximum wind speed. Based on this analysis, the optimal safe beach distance at the study site was identified as 202.2 m. Since the current beach distance (371 m) exceeds this value, the TSF was considered to be stable and satisfied the design safety factor of 2.0. However, this distance should be reassessed periodically to account for changes in the TSF geometry and other conditions. Furthermore, it applies only TSFs that are well-managed and feature a smooth, non-undulating beach surface with a consistent slope.

By Yongsik Jeong, Kwangmin Kim

Most tailings storage facility (TSF) failures occur in active, upstream-type TSFs, often due to extreme and unexpected weather conditions—specifically, heavy rainfall and strong winds. This case study of a TSF in southern Arizona examines the use of the optimum safe beach distance (Doptimal, the optimum distance between the crest and decant pond) as a tool for monitoring geotechnical stability and reducing catastrophic failures. A digital model of the TSF was used to determine the critical beach distance (Dcritical) under normal weather conditions, and Doptimal was then determined by adding incremental distances to account for the effects of heavy rainfall (Drainfall) and strong winds (Dwind). To overcome accessibility issues, a drone was used to map the TSF geometry and create a digital model. This model served as the basis for conducting a coupled stress-seepage, finite-element (FEM) analysis with a safety factor of 2.0 to assess geotechnical stability (Dcritical). The safe beach distance increments were determined using the PMP (probable maximum precipitation) and possible maximum wind speed. Based on this analysis, the optimal safe beach distance at the study site was identified as 202.2 m. Since the current beach distance (371 m) exceeds this value, the TSF was considered to be stable and satisfied the design safety factor of 2.0. However, this distance should be reassessed periodically to account for changes in the TSF geometry and other conditions. Furthermore, it applies only TSFs that are well-managed and feature a smooth, non-undulating beach surface with a consistent slope.

By Brenda M. Dixon

A matrix analysis of the differences between the camps and communities associated with the Britannia Mine is used to develop an analytical tool. The tool is intended to assist the mining industry as it embraces the many facets of sustainable development. A case study is used to support the identification of key factors that may predict the sustainability of a new mine town. Sustainable communities, like Britannia Beach, are discussed in the context of three pillars of sustainability: value of mining products to society; creating wealth; and, environmental integrity. A sustainable mine town may be viewed as a socio-economic asset as well as an asset to the mining industry.

May 1, 2006

By M. Sears, K. Mohamed, J. Addis, J. Wickline, G. Rashed

To better understand the load shedding and the stress transfer on coal pillars due to room-and- pillar retreat mining in deep cover panels, researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted a monitoring field study. Two sites, at overburden depths of 1,000 ft (304.8 m) and 1,500 ft (457.3 m), were selected in a room-and-pillar mine operating in Southern West Virginia. The deformation and stress changes in the roof and two adjacent pillars at each site were monitored during the retreat mining process. The monitoring results and field observations were used to calibrate large-scale FLAC3D models for each site. The calibrated models were used to assess different sizes of roof bolts installed in deep cover areas. INTRODUCTION Deep cover room-and-pillar retreat mining is an important emerging issue that will intensify in the future as shallower reserves are depleted (Mark, 2009; Chase et al., 2002). During pillar retreat mining, the likelihood of local and/or global instabilities increases due to elevated stress levels near the pillar line because of the abutment loading. In the last decade, approximately 31% of the room-and-pillar mining groundfall fatalities in the United States occurred during pillar retreat mining. Between 2013 and 2017, this proportion increased to 55%, of which 50% of these fatalities were due to falls of roof and rib that occurred during pillar recovery (MSHA, 2018). One interesting piece of information about pillar recovery fatalities was that the victim was nearly always under bolted roof. Sheared and broken #5 (5/8-in), fully grouted rebar bolt failure contributed to three of four fatal roof fall incidents that have occurred in deep cover retreat mines (NIOSH, 2010). This claim raised the following question at the study mine: Is it safe to use a 4-ft long #5 (5/8-in) rebar bolt grade 60 at a depth of cover more than 1,000 ft (304.8 m)? There was some concern about shear failure of the #5 (5/8-in) rebar bolt at a depth of cover over 1,000 ft (304.8 m). To answer the question and to reduce accidents and fatalities caused by ground falls due to room-and-pillar retreat mining in deep cover panels, the National Institute for Occupational Safety and Health (NIOSH) monitored the roof and rib deformation and the change in vertical pressure within two adjacent pillars during pillar recovery. The study was conducted at two deep cover sites in a room-and-pillar mine located in Southern West Virginia that operates in the Lower War Eagle (LWE) seam. The monitored sites were selected at 1,000 ft (304.8 m) and 1,500 ft (457.3 m) depths of cover. In this paper, site-1 represents the monitored site at 1,000 ft (304.8 m) of cover, while site-2 represents the monitored site at 1,500 ft (457.3 m) of cover. For this study, large-scale FLAC3D numerical models were calibrated based on both field observations and instrumentation results. The calibrated models were then used to compare the ground response and the induced stresses of two pillars at instrumented sites 1 and 2. The maximum lateral displacement (roof shift) obtained from the calibrated large-scale FLAC3D models was applied to a small-scale FLAC3D bolted models, the safety factor for axial stresses of the simulated roof bolts was calculated at the deep cover sites.

Jan 1, 2019

By Mostyn G. R

An important problem in rock engineering is to control the properties of artificial rock. A compaction technique for casting artificial rock specimens with controlled properties is described, i.e. using a compression-testing machine to compress the mixture. Uniform density is necessary to achieve uniformity of properties of the specimens, and uniform density can be obtained by using the specific pressing method presented. Rebound and borax content are important to the technique and have been studied as well.

Jan 1, 1992

By Da Zhao Gu

An important problem in rock engineering is to control the properties of artificial rock. A compaction technique for casting artificial rock specimens with controlled properties is described, i.e. using a compression-testing machine to compress the mixture. Uniform density is necessary to achieve uniformity of properties of the specimens, and uniform density can be obtained by using the specific pressing method presented. Rebound and borax content are important to the technique and have been studied as well.

Jan 1, 1992

By Frederick Jr. Prime

THE first catalogue of Geological Reports of the United States was prepared by Prof. O. C. Marsh, and published in the American Journal of Science and Arts for 1867, vol. xliii, second series. Since then the list has more than doubled, and it was thought that the publication of a new catalogue, brought down to date, would be useful to many of the members of the Institute of Mining Engineers. The compiler will be most thankful to have any omissions or inaccuracies in the list sent to him, to be published as a supplement in the next volume of the Transactions. Especially to have the correct title, number of pages, plates, and maps of any volume on the list to which an * is prefixed, as he has been unable to personally consult such works. A preliminary list was issued last February, which has been almost doubled by the kindness of many friends. The writer desires more especially to express the obligations he is under to the following gentlemen The Chief of Engineers, U. S. A.; Principal Dawson, Mr. G. M. Dawson, Drs. B. J. Harrington and T. Sterry Hunt, of Montreal; Mr. H. Engelmann, of La Salle, Ill.; Dr. F. V. Hayden and Prof. J. W. Powell, U. S. Department of the Interior ; Prof. E. W. Hilgard, University of California; Prof. Henry Y. Hind, Windsor, N. S.; Prof. C. H. Hitchcock, of Dartmouth College; Mr. Henry A. Holmes, State Librarian, Albany; Maj. Jed. Hotchkiss, Staunton, Va. ; Prof. W. C. Kerr, Raleigh, N. C.; Dr. J. S. Newberry, of Columbia College ; Prof. W. H. Pettee, of the University of Michigan ; Dr. Samuel H. Scudder, Prof. N. S. Shaler, and Prof. J. D. Whitney, of Harvard College ; Mr. Sanderson Smith and Prof. J. J. Stevenson, of New York ; Mr. Addison Van Name, of Yale College, and Lieut. Geo. M. Wheeler, U. S. Engineers. PHILADELPHIA, 907 Walnut Street, October 1st, 1879.

Jan 1, 1879