The "iron blow" at the Linda goldfield

From 1875 to 1877 Mr. Thureau held a position as Lecturer at the Bendigo (Victoria) School of Mines, of "Geology as applied to Mining," Mineralogy; also practical Mining, the Administrative Council of that institution arranged during each winter for a series of public lectures on Popular Science, and at such he elaborated a series of lectures upon the hydrothermal origin of the famous Bendigo Quartz Reefs. He was subsequently elected, upon unsolicited nominations and recommendations, as a Fellow of the Geological Society of London, which honourable position he still holds and treasures. The discovery of silver in the ash or mud, adds, for the first time, this metal to the list of elementary substances observed in the materials ejected from volcanoes, and the addition derived some special interest from the fact of this ash having come from the greatest volcanic (active) vents of that great "argentiferous" zone of the Andes. Small as would be the proportion of silver, it must represent a very large quantity of that metal ejected during the eruption, in view of the vast masses of volcanic ash, etc., distributed over the large area which is indicated by the fall of argentiferous ashes at a distance of 102 miles from the central crater to Bahia de Caraguez. Mr. Thureau states that, if silver, lead, iron, manganese, titanium, chlorium, mercury and other less important metals occur in volcanic ash or mud shown by frequent analyses, as derived, inter alia from the immensely rich argentiferous formations which that gigantic "vent" cotopaxi protrudes; a similar occurrence here on a smaller scale, within a well-known "auriferous zone" is not only feasible, but can be, or is now, demonstrated to be a fact. The only, and to us most valuable difference, is, that the South America ejecta expelled the silver in its ashes, whilst, with our "Iron Blow" the ash or "mud" is still retained within the "dead" vent or closed fissure, and happily for the colony at large, it is comeatable, and it can be extracted by future systematic mining operations, followed by skilful treatment for the rich gold it is reported same contains

Remarks on tin ore deposits at Mount Bischoff, Tasmania

Baron Von Groddeck, Chief Mining Councillor of the Hartz Mining Districts and Director of the Royal Prussian Academy of mines at Clausthal, Germany. Translated by G. Thureau, F.G.S., Govornment Geologist and Inspector of Mines, from the Special Imprint of the Journal of the German Geological Society of 1884. The Royal Academy of Mines at Clausthal was some time ago placed in possession of a very fine collection of Australian ores. That collection was presented to our Academy by M. Wagenknecht, of Aachen (a Fellow of the Royal Society of Tasmania). Amongst the samples were found a number of specimens. of Tin Ore, together with the rocks and the minerals said to be associated with same, from Mt. Bischoff, Tasmania. The series interested me, particularly on account of a piece of supposed Quartz-Porphyry, which rock, it was represented, is associated (according to the description of S. H. Wintle* and Geo. H. P. Ulrich) with those Tin Ores, and also because of some peculiar, dense, greyish-blue coloured masses of mineral which most frequently are found to enclose those Tin Ores. * S. H. Wintle ; Stanniferous Deposits of Tasmania. Trans. Royal Society of New South Wales, 1875, vol. ix., page 87. Geo. H. F. Ulrich. Written communication ; New York Book for Mineralogy, etc., 1877, page 494

GI2T/REGAIN spectro-interferometry with a new infrared beam combiner

We have built an infrared beam combiner for the GI2T/REGAIN interferometer of the Observatoire de la Cote d'Azur. The beam combiner allows us to record spectrally dispersed Michelson interference fringes in the near-infrared J-, H- or K-bands. The beam combiner has the advantage that Michelson interferograms can simultaneously be recorded in about 128 different spectral channels. The tilt of the spectrally dispersed fringes is a measure of the instantaneous optical path difference. We present the optical design of the beam combiner and GI2T/REGAIN observations of the Mira star R Cas with this beam combiner in the spectral range of 2.00 micron - 2.18 micron (observations on 22 and 25 August 1999; variability phase 0.08; V-magnitude approx. 6; seven baselines between 12m and 24m; reference stars Vega and Beta Peg). The spectrograph of the beam combiner consists of an anamorphotic cylindrical lens system, an image plane slit, and a grism. A system of digital signal processors calculates the ensemble average power spectrum of the spectrally dispersed Michelson interferograms and the instantaneous optical path difference error in real time. From the observed R Cas visibilities at baselines 12.0m, 13.8m and 13.9m, a 2.1 micron uniform-disk diameter of 25.3mas +/-3.3mas was derived. The unusually high visibility values at baselines >16m show that the stellar surface of R Cas is more complex than previously assumed. The visibility values at baselines >16m can be explained by high-contrast surface structure on the stellar surface of R Cas or other types of unexpected center-to-limb variations. The R Cas observations were compared with theoretical Mira star models yielding a linear Rosseland radius of 276Rsun +/-66Rsun and an effective temperature of 2685K+/-238K for R Cas at phase 0.08.Comment: 10 pages, 6 figures, see also http://www.mpifr-bonn.mpg.de/div/speckle, SPIE conf 4006 "Interferometry in Optical Astronomy", in pres

Plan of the Mount Lyell Gold Workings & Geological Sketch Plan of the Linda Gold Field

1 copy, part coloured on paper, slight tear on right crease. Left side - Mt Lyell, in four separate drawings detailing cross and longitudinal sections and indicating the location of various ores and rock types. Right side - Linda Gold Field indicating geographical and geological features. Drawn October 1886. Scale: 20 chains to an inch. Size: 70 x 64 cm. Drawn by G. Thureau F.G.S

Imaging the Algol Triple System in H Band with the CHARA Interferometer

Algol (Beta Per) is an extensively studied hierarchical triple system whose inner pair is a prototype semi-detached binary with mass transfer occurring from the sub-giant secondary to the main-sequence primary. We present here the results of our Algol observations made between 2006 and 2010 at the CHARA interferometer with the Michigan Infrared Combiner in the H band. The use of four telescopes with long baselines allows us to achieve better than 0.5 mas resolution and to unambiguously resolve the three stars. The inner and outer orbital elements, as well as the angular sizes and mass ratios for the three components are determined independently from previous studies. We report a significantly improved orbit for the inner stellar pair with the consequence of a 15% change in the primary mass compared to previous studies. We also determine the mutual inclination of the orbits to be much closer to perpendicularity than previously established. State-of-the-art image reconstruction algorithms are used to image the full triple system. In particular an image sequence of 55 distinct phases of the inner pair orbit is reconstructed, clearly showing the Roche-lobe-filling secondary revolving around the primary, with several epochs corresponding to the primary and secondary eclipses

Resolving Vega and the inclination controversy with CHARA/MIRC

Optical and infrared interferometers definitively established that the photometric standard Vega (alpha Lyrae) is a rapidly rotating star viewed nearly pole-on. Recent independent spectroscopic analyses could not reconcile the inferred inclination angle with the observed line profiles, preferring a larger inclination. In order to resolve this controversy, we observed Vega using the six-beam Michigan Infrared Combiner on the Center for High Angular Resolution Astronomy Array. With our greater angular resolution and dense (u,v)-coverage, we find Vega is rotating less rapidly and with a smaller gravity darkening coefficient than previous interferometric results. Our models are compatible with low photospheric macroturbulence and also consistent with the possible rotational period of ~0.71 days recently reported based on magnetic field observations. Our updated evolutionary analysis explicitly incorporates rapid rotation, finding Vega to have a mass of 2.15+0.10_-0.15 Msun and an age 700-75+150 Myrs, substantially older than previous estimates with errors dominated by lingering metallicity uncertainties (Z=0.006+0.003-0.002).Comment: Accepted for publication in ApJ Letter

Toward Direct Detection of Hot Jupiters with Precision Closure Phase: Calibration Studies and First Results from the CHARA Array

Direct detection of thermal emission from nearby hot Jupiters has greatly advanced our knowledge of extrasolar planets in recent years. Since hot Jupiter systems can be regarded as analogs of high contrast binaries, ground-based infrared long baseline interferometers have the potential to resolve them and detect their thermal emission with precision closure phase - a method that is immune to the systematic errors induced by the Earth's atmosphere. In this work, we present closure phase studies toward direct detection of nearby hot Jupiters using the CHARA interferometer array outfitted with the MIRC instrument. We carry out closure phase simulations and conduct a large number of observations for the best candidate {\upsion} And. Our experiments suggest the method is feasible with highly stable and precise closure phases. However, we also find much larger systematic errors than expected in the observations, most likely caused by dispersion across different wavelengths. We find that using higher spectral resolution modes (e.g., R=150) can significantly reduce the systematics. By combining all calibrators in an observing run together, we are able to roughly recalibrate the lower spectral resolution data, allowing us to obtain upper limits of the star-planet contrast ratios of {\upsion} And b across the H band. The data also allow us to get a refined stellar radius of 1.625\pm0.011 R\odot. Our best upper limit corresponds to a contrast ratio of 2.1\times10^3:1 with 90% confidence level at 1.52{\mu}m, suggesting that we are starting to have the capability of constraining atmospheric models of hot Jupiters with interferometry. With recent and upcoming improvements of CHARA/MIRC, the prospect of detecting emission from hot Jupiters with closure phases is promising.Comment: 30 pages, including 9 figures and 4 tables. Published in PASP in August 201

Last technology and results from the IOTA interferometer

The infrared optical telescope array (IOTA), one of the most productive interferometers in term of science and new technologies was decommissioned in summer 2006. We discuss the testing of a low-resolution spectrograph coupled with the IOTA-3T integrated-optics beam combiner and some of the scientific results obtained from this instrument