TERRESTRIAL REFRACTION". 13 



REMARKS ON THE RESULTS. 



1st. The most remarkable fact, which calls for 

 our attention, in the results of the present experi- 

 ments, is the almost invariable coincidence of the in- 

 crease of refraction with that of moisture; which will 

 appear still more forcibly, if we consider the results 

 of the following eight observations, all taken between 

 10 and 12 o'clock, P.M. on different nights, when I 

 was engaged in observing the eastern elongation of 

 the polar star; the depression of the S. extremity of 

 the line being taken by means of a referring lamp. 



Mean refraction 1' V S8. 



On comparing the hygromiCters, as they stood at 

 the time of these observations, with their position 

 when last noticed in the day time, it was found that 

 they had revolved, on a mean, 240" in the direction of 

 moisture. Now, the mean refraction of 55 observa- 

 tions, noticed in the tables, is 29" 74 ; and we have 

 seen that of the 8 observations taken at night (which, 

 from the stillness of the air, may be deemed to balance 

 a superior number) to be 1' 1" 38. Hence, it will 

 appear, that the latter is something more than double 

 the former. 



2d. We shall next advert to the comparative quan- 



