358 W. Ferrel—Relation between the Barometric Gradient 
ght be: no: 
was there a solitary instance in the pg 1830 in sa: bee 
an the 4-5 o’clock da 
larity of these oscillations in the torrid zone: “This regularity 
is such that, in day time especially, we may infer the hour 
from the height of the column of mercury without being in 
error, on an average, more than 15 or 17 minutes. In the tor- 
this ebb and flow of the aerial ocean undisturbed either by 
storm, tempest, rain, or earthquake, both on the coasts, and at 
elevations of nearly 13,000 English feet above the level of the 
* Phil. Trans., 1835, p. 167. 
