GEOGRAPHICAL DISTRIBUTION — CLIMATOLOGY. 



103 



95 



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X 



z 

 a: 



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90 



85 



80 



75 



70 



65 



60 



55 



50 



45 



40 



35 



30 



25 



35 



2b 



20 



15 



10 



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the Centigrade ; it is now geiierall.\- 

 in use on the Continent and almost 

 universally in scientific investigations. 

 On Fahrenheit's thermometer, the in- 

 strument in common use in this country, 

 the freezing point is marked 32^ on 

 an old assumption that the greatest 

 terrestrial cold was zero, an assumption 

 that has long since heen proved in 

 various ways and places to be fallacious; 

 the boiling point is 212°, the interval 

 between the two being 180°, so that 5^ 

 Centigrade is equal to 9° Fahrenheit. 

 The annexed diagram shows the com- 

 parative value of the degi"ee in each 

 scale. 



The division of the interval between 

 the two invariable points into 100 parts 

 is itself so suggestive and simple both 



in theory and practice as to require 



no justification. On the other hand, 



as ah-eady shown, the placing of the 



freezing point at 32° is quite arbitrary, 



and the division of the interval between 



the freezing and boiling points into 



180 units is equally arbitrary, and so 



far as the number itself is concerned, 



is supported by no data derivable from 



ascertained thermal laws. Practically 



the Fahrenheit degi'ee is too small to 



be appreciated by the most attentive 



of orchid cultivators, but to whom 



the Centigrade degree becomes an 



appreciable quantity', and consequently 



5°, 10°, 15° C, etc., are recognisable 



conditions of temperature apparent to 



the senses. But such temperatures as are expressed by 10', 50°, 60° F., 



etc., are complex notions rendered so by the circumstance that they 



do not themselves represent the number of units above an invariable 



point, but must be reduced to it by deducting the arbitrary number 



32. 



d L 



