SCOTLAND. Division XVIII.-NORTH-WESTERN COUNTIES (continued). 5:41 3:05 '74 2.95 4'77 1939 5.85 2.38 2:06 2:29 4:32 6.55 2:05 2.85 1°51 4:25 3:05 3:29 10'40 3.81 3.60 1'52 6.41 4:28 4'05 1'40 2'05 4'00 11.04 2'97 1'74 1.82 5'24 3'05 6:43 3.70 6.12 4'77 1:30 2:25 3176 3'59 3'75 3:45 3.78 2'94 5.65 4735 4:35 4'19 *28 1'77 2'04 3.48 2:30 4:32 1.56 2:37 2:45 61 10 43 13 1693 16.89 38.89 35 24 10115 4073 3082 26.96 51.66 35:35 25 31 23:34 2:05 1'02 2.33 6.95 7.60 3'33 4'30 1'24 3770 2°25 1.60 *99 1'59 .86 6.30 in. 3.88 4'08 5'00 '44 1.32 1'20 2:47 1'00 -83 1.31 1.92 2.61 3.70 3:00 1.86 1'00 1'51 1°51 3.10 5'30 *99 2'11 1.90 '90 I'12 1.81 •80 1'00 1.67 1'45 3.20 1.30 1.90 2.64 2'00 3.60 1.80 2.20 1'90 2.50 2175 2'94 2'40 6.90 3:46 2.78 3.70 1.90 2.91 2.68 2.50 2.20 5:00 2.68 4'40 7'40 3°56 2.60 2:30 2.10 3:05 2.85 4'60 2.20 4.86 2.86 3.05 3:09 4.20 2.80 2:27 2.12 3°70 2.20 4:10 3176 3'01 3.61 2.50 3'50 2:85 4:16 3'50 4'10 4'00 4:05 2.84 1'91 2.20 2.30 3'04 1953 3'20 2.10 3'44 3936 1874. 1875. 1874. 1875. in. in. in. in. in. 1874. 1875. 1874. 1875. in. in. 5.60 3'98 5'02 5.80 6.50 3°43 515 I.20 1939 1999 2.70 '50 3:46 1.50 3:00 4.20 5.60 2°33 2°27 2.92 1'01 2.20 2'10 2:25 1'44 Totals 30 35 4086 35.80 39'74 5443 54:18 37 77 46-86 35.50 33 19 32-83 35:57 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. September 3972 515 3°20 1978 2.65 1.38 2:49 1'91 3'47 75 179 3.89 1.28 3758 77 4'16 1'40 3°51 2.96 2:42 3.90 3.20 377 3'40 2.64 146 1972 2:46 429 472 2.63 3.87 5.68 2:00 3.40 4:26 4'17 3'01 Totals 3154 36 21 46.80 33.70 45'56 35.50 32 15 36.65 4506 50 47 29.66 32:35 3.66 3'93 4:58 3°29 3755 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. 3390 3647 29:02 3140 2852 29.84 31:48 41 39 26 29 32 18 46 34 38.84 5184 32.66 4.63 2.84 2.89 1874 1875 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. 1874. 1875. in. in. in. in. 1'71 4'29 1.98 1976 1949 261 2.85 147 2:05 2.62 in. in. in. in. in. in. 1.88 4'44 2.51 5.82 3.63 3.85 2'07 4'02 4'05 4:20 3°42 1'32 2:50 1.06 2°32 1.26 170 1.50 1932 1.28 1'27 2:44 *96 1969 1'00 2°39 193 2.80 2.81 155 1'40 '51 139 $29 2:48 *56 1'97 1'02 1'41 3.83 I'10 3°05 2774 2017 3°35 293 3°13 4.88 2.82 287 3.18 2.64 2:39 1.64 3.70 1'64 3:47 2.22 3.98 6:00 5'55 4'48 3.92 5'20 4'47 5.70 3'50 4:33 4'40 4:00 6.20 4'97 3.82 3'94 4933 4'99 4:35 4.80 3:19 4'10 4:25 3.61 5°19 2.68 4.84 4'98 7:05 4'47 5.86 3975 2.16 3:40 2'14 4:63 2757 5:10 3'20 4:28 2:50 4.62 3.89 4.86 3:02 4'95 5'41 7:06 3003 3363 3478 3198 4029 35 30 4485 36.10 35.50 3480 4571 38.96 44'40 4109 Ninth Report of the Committee, consisting of Prof. EVERETT, Sir W. THOMSON, F.R.S., Prof. J. CLERK MAXWELL, F.R.S., G. J. SYMONS, F.M.S., Prof. RAMSAY, F.R.S., Prof. A. GEIKIE, F.R.S., JAMES GLAISHER, F.R.S., GEORGE MAW, F.G.S., W. PENGELLY, F.R.S., Prof. HULL, F.R.S., Prof. ANSTED, F.R.S., Prof. PRESTWICH, F.R.S., Dr. C. LE NEVE FOSTER, Prof. A. S. HERSCHEL, G. A. LEBOUR, F.G.S., and A. B. WYNNE, appointed for the purpose of investigating the Rate of Increase of Underground Temperature downwards in various Localities of Dry Land and under Water. Drawn up by Prof. EVERETT, Secretary. A REMARKABLE series of observations have recently been taken in a boring at Sperenberg, near Berlin. The bore was carried to the depth of 4052 Rhenish (or 4172 English) feet, and was entirely in rock-salt, with the exception of the first 283 feet, which were in gypsum with some anhydrite. The observations were taken under the direction of Herr Eduard Dunker, of Halle an der Saale, and are described by him in a paper occupying thirtytwo closely printed quarto pages (206-238) of the Zeitschrift für Berg-, Hütten- und Salinen-Wesen' (xx. Band, 2 and 3 Lieferung: Berlin, 1872). The instrument employed for measuring the temperatures was the earththermometer of Magnus, which gives its indications by the overflowing of mercury, which takes place when the instrument is exposed to a higher temperature than that at which it was set. To take the reading, it is immersed in water a little colder than the temperature to be measured; the temperature of this water is noted by means of a normal thermometer, and at the same time the number of degrees that are empty in the earth-thermometer is noted. From these data the maximum temperature to which the instrument has been exposed can be deduced, subject to a correction for pressure, which is not very large, because the same pressure acts upon the interior as upon the exterior of the thermometer. In the following résumé (as in the original paper) temperatures are expressed in the Réaumur scale, and depths in Rhenish feet, the Rhenish foot being 1.029722 English foot. Observations were first taken, at intervals not exceeding 100 feet, from the depth of 100 feet to that of 4042 feet, the temperature observed at the former depth being 11°, and at the latter 38°.5; but all these observations, though forming in themselves a smooth series, were afterwards rejected, on the ground that they were vitiated by circulation of water and consequent convection of heat. It has often been supposed that though this source of error may affect the middle and upper parts of a bore, it cannot affect the bottom; but the Sperenberg observations seem to prove that no such exemption exists. When the bore had attained a depth of nearly 3390 feet, with a diameter of 12 inches 2 lines at the bottom, an advance-bore of only 6 inches diameter was driven 17 feet further. A thermometer was then lowered halfway down this advance-bore, and a plug was driven into the mouth of the advance-bore so as to isolate the water contained in it from the rest of the water above. After twenty-eight hours the plug was drawn and the thermometer showed a temperature of 36°.6. On the following day the temperature was observed at the same depth without a plug, and found to be 33°-6. Another observation with the plug was then taken, the thermometer (a fresh instrument) being left twenty-four hours in its position. It registered 36°.5, and again, without plugging, it gave on the same day 33°9. It thus appears that the effect of convection was to render the temperature in the advance-bore 3° R. too low. Apparatus was then employed for isolating any portion of a bore by means of two plugs at a suitable distance apart, with the thermometer between them. This operation was found much more difficult than that above described; but in several instances it gave results which were deemed quite satisfactory; while in other instances the apparatus broke, or the plugging was found imperfect. The deepest of the successful observations by this method was at 2100 feet, and the shallowest was at 700 feet. The first 444 feet of the bore were lined with iron tubes, between which the water had the opportunity of circulating even when the innermost tube was plugged; hence the observations taken in this part were rejected. All the successful observations are given in the third column of the following Table, subject to a correction for pressure; and, for the sake of showing the error due to convection in the ordinary mode of observing, the temperatures observed at the same depths when no plugs were used are given in the second column : These temperatures are not corrected for pressure, but they are corrected for rise of zero in the normal thermometer; and this last circumstance explains the difference of 0.4 between the temperature 36°15 here given and 36-55, which is the mean of the above-mentioned observations at the depth of 3390 feet. Another proof of the injurious effect of convection was obtained by comparing the observed temperatures (without plugging) in the first 400 feet of the great bore, designated Bore I., with the temperatures observed at the same depths during the sinking of another bore, designated Bore II., near it, the observations in this latter being always taken at the bottom. The following were the results : The temperature at the depth of 100 feet in the great bore thus appears to have been raised about 2° R. by convection. The following is a Table of the successful observations, corrected for pressure: |
