318 



Mr. Hinds on Climate in connexion 



a further compensation ; when the temperature is sufficiently 

 depressed the insensible moisture is precipitated, and the 

 caloric necessary to its existence as an aeriform body is given 

 out and becomes sensible. 



The relative proportion of moisture in the atmosphere varies 

 with circumstances ; temperature has a powerful influence over 

 the quantity suspended, and a change in the amount occurs 

 as the temperature alters through the seasons. Alterations 

 of temperature in small intervals of time have but a trifling 

 effect, and it is rather the mean heat of a reasonable portion 

 that it follows. Between the conditions of the vapour of the 

 atmosphere and the circumstances of evaporation there are 

 such points of resemblance, that an estimate of one puts us in 

 possession of the chief features of the other. The mean tem- 

 peratures have been seen to advance as the latitude is dimi- 

 nished, or as the equator is approached, and the activity of 

 evaporation and the quantity of suspended vapour proportion- 

 ately increase from the poles to the equator. The higher the 

 mean temperature, other things being the same, the greater is 

 the force of evaporation, and necessarily the quantity of 

 moisture suspended in the air. 



Not many data have hitherto been obtained as to the 

 amount of evaporation in different latitudes, or under a variety 

 of mean temperatures. To supply this deficiency a table has 

 been calculated for the rate of evaporation for every 5° from 

 the equator to the pole ; it has been constructed on the ad- 

 mission that the deposition of moisture takes place in England 

 at 6° below the mean temperature. It is not improbable that 

 the mean point of deposition below the mean temperature 

 varies very little in different latitudes, and that a depression 

 of 6° below the mean will be nearly as correct for the tropics 

 as for our own climate. 



Latitude. 



Mean 

 Temp. 



Evaporation in 

 inches. 



Difference in 

 the Yearly 

 Evaporation. 



Latitude. 



Mean 

 Temp. 



Evaporation in 

 inches. 



Difference in 

 the Yearly 

 Evaporation. 



Daily. 



Yearly. 





Daily. 



Yearly. 







o 

 85 



•18938 



69-10 





50 



o 



53-3 



•07312 



26-71 



4-18 



5 



84-6 



•18717 



68 32 



•78 



55 



48-8 



06327 



23-09 



3-62 



10 



83-4 



•18085 



66-01 



2-31 



60 



44-5 



■05517 



20-14 



2-95 



15 



81-4 



•17073 



62-32 



3-69 



65 



40-6 



•04860 



17-74 



2-40 



'20 



78-7 



•15786 



57-62 



4-70 



70 



37-3 



•04362 



15-92 



1-82 



25 



75-4 



.14133 



52-32 



5-30 



75 



34-6 



•03990 



1456 



1-36 



30 



71*5 



•12769 



46 61 



5-71 



80' 



32-6 



•03732 



12-62 



•94 



35 



67-2 



•11222 



40-96 



5-65 



85 



31-4 



•03584 



13-09 



•53 



40 



62-7 



•09785 



35*72 



5-24 



90 



31 



•03537 



12-91 



•18 



45 



58 



•08463 



30-89 



4-83 













This table is theoretical, and constructed on the foundation 



