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Abridged adit argentiferous auriferous auriferous deposit auriferous Jacotinga beds Brazil British Association calcareous-spar Canga Caradon Carvoeira Catta Preta Channel Islands Chili chloritic clay-slate copper-mining copper-ore copper-pyrites Cornwall and Devon Cornwall Geol cross-veins detrital detrital gold different depths Eardiston elevation felspathic fins following columns Geological Geology of Cornwall gold-mines Gongo Soco granite Henwood hornblendic Ibid iron-ore iron-pyrites Itabirite Jacotinga July Lake Superior large stream lead-ore limestone Liskeard lode Longitudinal Section Magnetic declination Marke Valley Mean depth Mean ratios Mean temp mean temperature Menheniot metalliferous deposits metals micaceous midi miners Morro Velho native copper Phil pied Progress of Mining proportion of tin-ore proportions of silver pumped Quarterly Journal quartz quartz Itabirite quartz-rocks rocks and lodes Royal Saint Sandstone schistose silver-ore slate small depths subterranean temperature Table XIV Table XXII talcose température moyenne temperatures increase temperatures observed thermometers thermomètre Trans Transverse Section vein-stone veins Webb & Geach whilst
Pagina 766 - L'instrument était muni d'un cordon qui permettait de le retirer pour le consulter. Lorsque le thermomètre était en expérience, on bouchait l'orifice du trou avec un morceau de carton sur' lequel on appliquait une grosse pierre. La température moyenne du village de Zupia avait été fixée à 2l°,5 par de nombreuses séries d'observations' thermométriques faites en 1825, 1826 et 1829- Zupia est élevé au dessus de la mer de 1225 mètres.
Pagina 765 - On the changes of temperature which take place — at the same, and at different, times, — on the surface and at depths of three, six, and nine feet in the Canga, at Agoa Quente in Brazil The following observations were made with a view to ascertaining the rate at which solar heat penetrates the earth. The high granitic ridge of the Cara^a,* situate in Long. 43° 10- W., Lat 19° 50...
Pagina 738 - ... to 12-5 fathoms] high. If therefore we should * * * consider the sea level as the surface, we shall have a depth of [116-6 fathoms] corresponding to [7°-343 or l°=15-8 fathoms]. " It seems to be fully established * * * that there was a gradual though a slight diminution of temperature as the observations proceeded. Thus the temperatures were during the first half i of the period I , ' „ the second half ) of the period ( - , in air 57-613 .. in the rock 57-718 . . in the lode 58-000 56-697..
Pagina 763 - Dolcoath in 1821 — 2 and 1827, it appears that the temperature was increased only 4° in one level with an increased depth of...
Pagina 740 - ... 52-3.§ The mean annual temperature at the Bearhaven mines, therefore, is probably much the same. The temperatures observed at different depths have been, — * Jukes & Kinahan, Explanation to accompany Sheets 197 and 198 of the Geological Survey of Ireland, pp. 13, 20. Ante, p. 602, Table XX. t Smyth, Explanations to accompany Sheets 197 and 198 of the Geological Survey of Ireland, pp. 30 —3. Ante, pp. 603—8, Table XX.
Pagina 742 - Reprinted with revisions and corrections up to 1851. ENGLAND (Continued) 484. WEBB, — , and GEACH, — . History and progress -of mining in the Caradon and Liskeard district. Not available to the author*. WEEKS, JOSEPH D. See No. 1372. 485. WEST, HE Cornish tin mining.
Pagina 723 - Long. 43° 50' W., Lat 19° 58- 20" S. Mine of Morro Velho* Elevation of the surface about 3,250 feet above the sea. Wrought in clay-slate. " If, in the absence of observations at midnight, and at 3 am, we assume the mean temperatures at those hours to have been 45°, which at this season cannot be wide of the truth ; we have an average of about 48°' 6 during the twentyfour hours.
Pagina 761 - Бeреги of the British Astociation, for 1864, Part II. p. 70. (Abridged) * " Numerous observations show that, whilst the conditions of the works on mines are unchanged, the temperatures at considerable depths are constant ; but it seems not to have been ascertained whether the temperature of any spot —after other openings were extended beneath it — remained the same as it had been when it was the bottom of the mine. To invite enquiry on this subject, I venture to offer the following comparisons....
Pagina 738 - Copper Mine ; * # * one being sunk three feet into the rock, and another into the lode at a depth of [129 fathoms] from the surface. A thermometer * * * was hung in the gallery or level where these were placed. • * * " These mines are in lat. 52° 8
Pagina 721 - ... deep — mine, by placing the thermometers in holes which had sometime before been purposely bored in the several limestones ; * all others were determined in streams of water immediately as they issued J from the various rocks and veins. * Postea, p. 725. t " It is in the solid rock that the best observations, and those most suited to the purpose of philosophical reasoning, are to be obtained.