224 



The tube which connected the bulb with the reading part above 

 ground was made capillary, so as to contain as little liquid (alcohol) 

 as possible. Notwithstanding, all the observations have been ri- 

 gorously corrected for the inequality of temperature of their stems, 

 and likewise for the expansion of the liquid above ground. The 

 observations were commenced in February 1837, and have been 

 made once every week since. After being corrected they were 

 projected in the form of Curves : and the general consistency of 

 these with one another, and the peculiarities proper to each station, 

 are such as to give considerable confidence even in the first ap- 

 proximation, which extends from February 1837 to February 1838. 



I. The general form of the curves at all the stations correspond- 

 ing to diflFerent depths agre perfectly with what has hitherto been 

 observed under similar circumstances. As we descend, the curve 

 becomes more even, and flatter, the range rapidly diminishing, and 

 the epochs of minimum, mean, and maximum temperature occur 

 later. 



II. The mean temperature of the soil appears to increase as we 

 descend (this has been observed at Brussels and elsewhere). At 

 the Experimental Garden the mean annual temperature is, at 3 feet 

 (French), 45^54 Fahr. ; at 6 feet, 46.70; at 12 feet, 46^90; at 

 24 feet, 47°.28. The Craigleith observations are ambiguous in this 

 respect. 



III. The annual ranges at the thi-ee stations and at the different 

 depths, are the following : 



3 Feet. 



C Feet. 



Now it is known by theory that the range ought to diminish in 

 geometrical progression as the depths increase arithmetically ; and 

 accordingly these results may be very closely represented by loga- 

 rithmic curves, having different Moduli at each station, depending 



was sunk along with the deepest thermometer, with a view to test the ap- 

 plicability of M. Peltier's apparatus to this object. Several observations 

 closely agreeing with the thermometer have thus been made. 



