CHAP. 9. AND PRESSURE. 245 



sinks and rises alternately, by Showers ; and 

 when greater or more sudden depressions take 

 place, Storms are generally the consequence. 

 These observations are, generally speaking, 

 true ; though, perhaps, with occasional and rare 

 exceptions ; for sometimes the Barometer shall 

 sink, and even the clouds present all the appear- 

 ances of Rain, and yet the rainy symptoms shall 

 subside, and clearness return without any fall. 

 But there appear to me to be some other re- 

 markable connexions between the state of the 

 Barometer, and other phaenomena, which do 

 not appear to have been noticed. 



Sudden changes in the barometrical pressure 

 of the air produce certain corresponding effects 

 on the nervous system : thus a rapid rise in 

 the Barometer will generally cause a peculiar 

 sensation in the ears of many persons amounting 

 to a degree of temporary deafness ; and what 

 renders it more strikingly apparent, that the 

 increase of atmospherical pressure is the cause 

 of the sensation is, that a sudden descent from 

 high mountains has often the same effect, as I 

 experienced myself after coming down from 

 Cader Idris, Aug. 14, 1814, and again after 

 descending from Skiddaw, May 19, 1816. I 

 perceived it also in a less degree during the 



