'4te Naiural-Pkiiosopkical Collections. 



two springs observed at difFerent periods gave +6" 2. From other observations 

 the mean temperature of the earth at Casan may be taken at +5°. 



Mean Temperature of the Air at Zlatooust, lat. 55° 8', long. 57° ; height 

 above the level of the sea 370 metres. 



The observations made by M. Eversmann, from 1817 to 1820, in the morning, 

 and at 2 p.m. gave for the mean result, 



And for the mean of all the months of these two years, +0,6 



Temperature of the Earth at Kisriekejvaf to the east of the Ural. — Lat. 64* 

 fi', long. 60° ; 300 metres above the level of the sea. At 25 metres beneath the sur- 

 face, in a disused gallery, the water of a pool was + 3° 5 R. 



Temperature of the Mines at Bogoslovsk, lat. 60° long. 60°, height 2t|0 

 metres — In the mines of Tousjensk ? to the east of Bogoslovsk, the temperature 

 of drains, at 112 metres depth, was +5°. In those of Frolow? at 66 metres, 

 +3° 2 ; a spring at 56 metres, +2° T. 



On dividing the sum of the differences of depth by that of the differences of 

 temperature, we find an increase of depth of 24 m. 4 for each degree of the oc- 

 togesimal thermometer. 



On comparing the results with those of other observers, we obtain, for the 

 mean result, 25 m. 25 for every octogesimal degree. 



We commit an error by deducing the temperature of the earth from that .of 

 springs, unless they be very deep, — perhaps at least 25 metres. 



Temperature (\f the Earth at Nijne'i-Taghilsk, lat. 58°, and at WerkbotoimCf 

 a t. 59°. 



These two places are on the eastern acclivity of the Ural, at nearly 200 metres 

 devation. At the mines of Nijnei-Taghilsk, the water at 65° had a temperature 

 of + 3° 9 R., which gives, on deducting 25 m. of depth, 2° 3. A pit of 5 m. 

 gave + 2° 6. At Verkhotourie a spring gave + 2° 1, from which deducting 

 + 0,2, we have + 1° 9. 



The observations of Wahlenberg, Humboldt and de Buch have proved that, in 

 high latitudes, the temperature of springs is greater than the mean temperature 

 of the air, and that the contrary is the case in low latitudes. M. Kuppfer has 

 collected, in a table, the results of the most exact observations, in addition to 

 those which he has himself made ; and it results that the temperature of the 

 earth changes also with the longitude. 



On distributing the observations under four meridians, reducing them to the 

 level of the sea, and adding 2-5th° R. for every hundred metres of elevation, we 

 find, taking the extreme results. 



At the 1st meridian of 0° long, for 15° and 60° lat., 19° 6 and 7° 0. 



At the 2d meridian, 60° long, east of Paris, for 30° and 60° lat., 18° and 3*. 



At the 3d meridian, 60° long, east of Paris, for 54° 4', and 60° lat., 4° 7, and 

 2° 3. 



And at the 4th meridian, 80° long, west, for 10° and 40' lat., 2.{f 6 and 

 10° 2. 



From which we may deduce the following results : 



1st. That the <^emperature of the earth is not equal throughout the same pa- 

 rdlel : drawing lines through all the points of equal temperature, we have curves 

 which M. Kuppfer calls isogeothermal lines, whose inflexions resemble those 

 of the isothermal lines, without being confounded with them. 



2d. The temperature of the earth decreases regularly from the equator to the 

 pole, which explains why the temperature of the earth, in low latitudes, is inferi- 



