FIELDS OF PRESSURE AND MASS IN THE ATMOSPHERE. 



99 



Fig. 14. Field of mass, Sept. 23, 1898, represented by charts giving 

 the average specific volume (m 8 /ton) of the air in is"baric 

 sheets, or the thickness of these sheets in dyn. meters. 



Fig. 13. Field of pressure, Sept. 23, 1898, represented by topographic- 

 charts giving the height of isobaric surfaces in dyn. meters. 



