1846.] 



MOTION OF GLACIERS AT DIFFERENT SEASONS. 



129 



effect of the season of the year is beautifully shown, the follow- 

 ing being the minimum and maximum values : 



Glacier des Bois, No. I., minimum in December 

 Glacier des Bois, No. I., maximum in July . 



Ratio of maximum to minimum 



Glacier des Bois, No. II., minimum in January 

 Glacier des Bois, No. II., maximum in July 



Ratio of maximum to minimum 



Glacier des Bossons, No. I., minimum in March 

 Glacier des Bossons, No. I., maximum in May 



Ratio of maximum to minimum 



Glacier des Bossons, No. II., minimum in March 

 Glacier des Bossons, No. II., maximum in June 



Ratio of maximum to minimum 



Daily motion in inches. 



3J:1 



From these observations we may deduce the annual motion 

 from November 1844 to November 1845, with considerable ex- 

 actness. Allowing for the fractional parts of a year, we obtain 

 the following results, amongst which I have included a separate 

 computation of the mean daily motion for the summer period 

 (April October), and the winter period (October April) : 



I. From this Table we deduce, in the first place, a mean 

 annual motion far greater than has hitherto been observed, or 

 perhaps suspected in any glacier, that of near 300 yards, or 



K 



