OF TIIE OBSERVATIONS FOR ATMOSPHERIC PRESSURE. K)l 



The results show conclusively that the hourly and bi-hourly series give the 

 same mean, and that the mean, deduced from six observations a day, does not 

 materially differ from either; no correction need therefore be applied to daily 

 means derived from readings at intervals of two and four hours. 



Diurnal Variation of the Atmospheric Pressure, 



The diurnal variation, which is almost vanishing in the higher latitudes of the 

 Arctic regions, can only be satisfactorily traced by means of a combination of a 

 great number of observations ; it is also frequently masked by the great irregular 

 fluctuations in the atmospheric pressure. The observations were, therefore, grouped, 



