Se eT ee ee ey ee ey a Oe eee ee ee 
Se ee 
LO ee ne aS ee Cee eT 
Sa ee See ee er ey ee ee ee ree cide it er a i si 
relative to the Earth’s Surface. 41 
31. Since the atmosphere is depressed in the middle of cy- 
clones, they must sensibly affect the barometer; and this is the 
true cause of all the great barometrical oscillations, as was first 
suggested by Redfield.* As the cyclone approaches, there is 
generally a very slight rise of the barometrical column, which is 
at its maximum at the greatest accumulation near the external 
: ‘ 6 
