REVIEWS — CLIMATOLOGY OF THE UNITED STATES. 33 



a moving body, usually progresses eastward at the rate of three hundred miles ia 

 twenty four hours ; and it is quite usually attended by a similar succession of 

 changes until it reaches the Atlantic coast." p. 131. 



Passing on to the west of the Eocky Mountains, we find one of the 

 leading characteristics to be that of intense aridity. In illustration 

 of this the temperature of evaporation, or that indicated by a wet 

 bulb thermoQieter, will frequently remain for several days together20'^ ■ 

 below the temperature of the air. At the driest part of the day this 

 difference will sometimes amount even to 25'^ or 30'', and will con- 

 tinue for several months without falling short of 20'^. 



A remarkable effect of this dryness is the long resistance which 

 animal substances offer to putrefaction, by which travellers are 

 enabled to carry meat for almost an unlimited time without using 

 salt or any preparative process. 



Another remarkable feature in the Pacific climate is the extraor- 

 dinary daily range of temperature, compared with that prevailing 

 elsewhere, that sometimes takes place. Officers engaged in surveying 

 have reported noon-day temperatures of 87° and 92°, followed at 

 night by a depression below the freezing point, and in one locality a 

 mean daily range during a fortnight of 55°. These ext^mes are 

 doubtless chiefly due to the extreme clearness of the atmosphere, 

 which its dryness produces, and which facilitates the absorption of 

 heat "by day and its loss by night. 



The remarks on the Pacific climate are thus summed up : 



" In review of the "distinctions of a general character belonging to the interior 

 a:nd Pacific climates, they may be briefly stated to be aridity first ; isolation of 

 districts and conditions next ; and periodicity of rains, winds, and some other lead- 

 ing phenomena in distinction from equally distributed rains, <fec., as in the Eastern 

 United States. The isolation of phenomena implies an interruption of the sym- 

 metry so characteristic of the East, and all the important differences which follow 

 in this ti-ain. Extreme contrasts, diversities, and transitions belong Tiere to place 

 or locality, and in the East to time." p. 164. 



Space will not admit of the introduction here of farther extracts ; 

 we must be content, therefore, with indicating — as portions of the 

 book peculiarly adapted to interest the general reader — the chapter 

 en winter storms, and the succeeding chapters on climate considered 

 in reference to vegetable productions, and in its sanitary relations. 

 Compelled, however, to bring this tiotice to a conclusion, we woxdd 

 regret indeed were our intercourse with the volume itself to terminate 



VOL. Ill; C 



