28 BAROMETRICAL REGISTER KEPT AT ECCLES MANSE. 



The greatest elevation of the barometer was 30.1 inches, which it 

 attained several times, but more especially on the 1 0th February and 

 21st and 22nd September. 



The range of the barometer for 1832 is thus found to be one inch 

 and a half. The lowest boihng point of water was therefore 209°. 32 

 Fahrenheit, and tlie highest 212°. 17 ; the mean for the whole year 

 211°. 08, the range of boiling point being 2°. 85. 



2. A fall of lou was frequently attended with a shower, or even 

 heavy rain. A subsidence of rgo was very speedily followed by the 

 same consequences, as on the 14th and 15th August 1832. This result 

 forms a striking contrast with observations made between the tropics, 

 where we find, in similar circumstances, a more decided fall of the 

 mercury, seldom less than iV previous to the occurrence of rain, which 

 is about double the subsidence as obtained by this register. 



3. When frost occurred, the barometer generally rose from j-gg to 

 half an inch. Snow most commonly depressed the mercurial column, 

 while a thaw elevated it. 



4. The mean height of the barometer for the two years 1832 and 

 1833 is, after correction for temperature, (29.523 -f 29.257)^-2 = 

 29.390 ; from which we may calculate the elevation of Eccles above 

 the level of the sea. 



By the formula 45 (9 — g), appHed to the diminution of temperature 

 by the rarefaction of air, reckoning the density of the air in the same 

 latitude at the sea 1, and assuming 29.82 as the standard barometer 

 pressure for Britain, we have 29.82 : 29.39 : : 1 : .985 = density of air 

 at Eccles. Then 1 -^ 985 =^ 1.015. By substitution the formida 

 becomes 45(1.015—985) = 45 X 030 = 1.35 = difference of tempera- 

 ture between the two stations. 



Assume the law of equable progression, 1 : 270 : : 1.35 : 364^ = 

 feet above the level of the sea, shewing a gentle ascent of 315^ feet to 

 Stitchell, which is about five miles distant, and 680 feet above the sea, 

 according to Mr Blackadder, and 533A^ to Hume Castle, which, by the 

 same authority, has an elevation of 898 feet. 



We arrive at the mean temperature, by comparing the mean tempera- 

 tures of stations well established. The mean temperature of Glasgow, 

 which is situated in 55° 31' 32" north latitude, is 47° 75', and that of 

 London 50°, St Pauls being situated in 51*^ 30' 49" north latitude; 

 from which it appears that the temperature of the atmosphere dimin- 

 ishes 0.53 Fahrenheit, for every additional degree of latitude. Eccles 

 is situated in about 75° 40' north latitude, or 11^ miles south of 

 Glasgow, with a difference of + vo" temperature. Hence we have for 

 Eccles a mean temperature of 47*^ 85'. By deducting the difference of 

 temperature of the two stations, as obtained by the formula, from the 

 standard temperature 48° 66' — 1°.35 = 47° 31' = the mean tempera- 

 ture, which is, however, probably less than the true number by a 

 considerable sum. 



