104 



KIICORD AND REDUCTION 



DicK.NAL Variation op Atmospheric Pbessdhe at Post Ki:>m dt. 

 Latitude 72°.0 N. 



45 

 40 

 35 

 30 



20 

 15 



10 

 05 



.895 

 .890 



Mi.lu't 2 



10 Noon 



10 Midn't 



These curves have in common a maximum at about 7h P. M., and a minimum 

 at about 4 J A. M.; the hour of maximum at Van Rensselaer Harbor was 10 P. M., 

 whereas a minimum at 4 A. M. is hardly perceptible at this place. A secondary 

 maximum is plainly indicated at Port Kennedy about noon, and a secondary mini- 

 mum about 22 P. M., which secondary minimum seems to correspond with the 

 principal minimum at Van Rensselaer Harbor at li P.M. 



The range of the diurnal fluctuation of the barometer is as follows: — 



1. Iu Baffin Bay 



2. At Fort Kennedy . 



3. At Van Rensselaer Harbor 



0.028 inches. 

 0.048 " 

 0.010 " 



Hence, between latitudes 72°. 2 and 78°. G, there is a diminution in range of 0.028 

 inches; at this rate, the diurnal fluctuation would become insensible (be less than 

 0.001) in about 81° north latitude. 



The following table of observed bi-hourly means is added for convenience of 

 reference and for comparison : — 



Hour. 



2 



4 



6 



8 



10 



Noon 



2 



4 



6 



8 



10 



Midn't 



Mean . 



Baffin Bay. 

 Lat. 72 .S. 



29.733 

 .730 

 .726 

 .731 



.750 

 .713 

 .745 

 .753 

 .756 

 .756 

 .753 

 .713 



29.743 





29.925 



29.765 



Annual Variation of (he Atmospheric Pressure. 



The mean monthly height of the barometer is obtained directly from the pre- 

 ceding tables, -bowing the diurnal fluctuation, by applying to the monthly mean 





