24 On the Heat of Springs, [July, 



180S. Temperature. 

 16 October 44-06° 



13 November 44*06 



14 December 44*24 



These, and all the following observations, were made with the 

 same thermometer, each degree of which was 0-0S48 English inch 

 in length.* Hence the tenth part of a degree could be easily 

 observed on it. I thought it most accurate to graduate this thermo- 

 meter myself; and to determine its highest fundamental point by 

 means of the heat of the body. When we put the bulb of the 

 thermometer under the tongue after seven or eight hours' sleep in 

 the morning, and shut the mouth ; if we observe tbe height of the 

 mercury by means of a concave mirror, we shall find tbat after an 

 interval of a quarter of an hour it will stand at 98-366°. This 

 experiment was frequently repeated, and the height of the thermo- 

 meter never varied more than one or two fifths of a degree. If it 

 he made in the same way about an hour after dinner, the mercury 

 will stand at 99*32°, and this is the highest degree which it reaches. 

 In the evening, after a little rest, it rises only to 97"52*; and this 

 is tbe lowest point. However, by means of warm food, the ther- 

 mometer may be raised for an instant as high as 100 - 22°; and by 

 means of cold food it may be prevented for a short time from rising 

 higher than 9716°. After I had graduated my thermometer in 

 this manner, 1 found it to agree very well with a thermometer of 

 Dollond, with which Baron Hermelin had presented me in the year 

 180/, for my expedhiun to Lapland. 1 fixed the tube to a scale of 

 hard fir, and to be able to determine correctly the height of the 

 mercury, a slip of waxed j'Sper, graduated on both sides, was pasted 

 over one half of the tube : and below it was a black mark which 

 could be moved, and placed over against the place at which the 

 mercury stood. f 



I surrounded the bulb, which is 0*4712 English inch in diameter, 

 with a triple fold of cloth, and left it in that state for an hour in the 

 spring : as I had previously ascertained that it acquired the tempe- 

 rature of the liquid in which it was placed in three quarters of an 

 hour. 



From these experiments we mav conclude that the temperature 

 of the Brennerei spring at Upsala, during a year and a half, was 

 constantly 44*06°, and therefore that this is the true temperature of 

 the earth at Upsala. 



Two other springs, well suited for such observations, on account 

 of their strength and position, gave tire following results : — 



* The thermometer was of Celsius; so that each degree was equal to 1*8 

 degree of Fahrenheit. — T. 



Mure recently, in the year 18)0, Dr. Wahlenberg attached an ivo*v scale to 

 hi- thi i meter ; bence in r is later observations there isa difference of one or two 

 tenths of a degree from his former ones. — Von Budu 



