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adit Agoa Quente auriferous auriferous deposits auriferous Jacotinga beds Berezovsk Brazil British Association calcareous Canga Caradon Carvoeira Chafiarcillo Channel Islands Chili chloritic clay-slate coal-measures copper-ore Cornwall Geol cross-veins deep deposits containing detrital detrital gold different depths dips displacements heaves Eardiston elevation extent and produce fathoms feet felspathic fins following columns Geology of Cornwall gold obtained gold-mines Gongo Soco granite Henwood hornblendic hornblendic rocks Ibid intersected iron-glance iron-ores iron-pyrites July Lake Superior large stream limestone Liskeard lodes Mean depth Mean ratios Mean temp mean temperature Menheniot metalliferous deposits metals micaceous miners Morro Velho native copper Phil precipitation of copper produce and profits Progress of Mining proportion of tin-ore proportions of gold proportions of silver pumped pyrites quantities quartz quartz-rocks ritic rocks rocks and lodes Sandstone schistose shaft silver-ores subterranean temperature surface Table XIV Table XXII Tables VII talcose temperatures increase temperatures observed thermomètre Trans vein-stone veins Wheal widths xxiv
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 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 42 fathoms, giving a ratio between the stations of 1° increase in 10-5 fathoms ; and in another level the temperature was actually 2° to 2°'5 less than in 1822, although 42 fathoms deeper than the mine was then.
Pagina 777 - ... must, of course, depend, in some measure, on the nature of the surface.* The following columns set forth the means of observations, at the surface, as -well as at depths of three, " The observations from which the following table has been deduced were made at Alverton, near Truro, in 1852 — 3. * * * Four pits, about two feet deep and two feet wide, were dug in good healthy garden loam. [The first] was filled with yellow clay frem the clay-slate ; [the second] with pure white sand, from the...
Pagina 721 - The reasons for this preference are ; — that the temperature of the air in mines is affected, not only by the presence of the workmen, the combustion of candles, and the explosion of gunpowder, but also by the warm or cold air which is brought to the same spot by the varying directions of the currents underground, which are more or less influenced by the changes of wind at the surface; that the rocks, forming the sides of the shafts and levels, must, to a certain extent, partake of the temperature...
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 768 - Le thermomètre a été placé à i pied dans le sol , dans une salle basse de la maison du surintendant des mines. La température moyenne de celte maison déduite d'une année d'observations est de 20°,5.
Pagina 769 - Les observations que je viens de rapporter établissent, ce me semble, d'une manière certaine que la température moyenne d'un lieu abrité situé entre les tropiques, est donnée par la température du sol prise à 1 pied de profondeur. . Une fois que j'eus reconnu la possibilité* d'obtenir, par un moyen aussi prompt que facile, la température moyenne d'un lieu , j'emportais dans mes voyages un fleuret de mineur, à l'aide duquel je pratiquais aisément dans le sol...
Pagina 721 - After most careful consideration of the subject, and consultation with others who have also been engaged in this enquiry, it has been thought best to confine the observations, as much as possible to the temperature of the streams of water immediately issuing from the unbroken portions of the rocks and veins. The reasons for this preference are ;—that the temperature of the air in...
Pagina 738 - The Bearhaven mines are opened in rocks, of the * " Thermometers were placed, in August 1843, in the deepest part of Knockmahon 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