476 



AGRICULTURAL REPORT. 



between the freezing point and the boiling point of ■n-ater, a graduation it is 

 greatly to be regretted not yet of universal acceptance with our countrymen.* 



Tliirty-two degrees of Fahrenheit becomes their zero, and as th(! degrees 

 below thin point or that of freezing are of no account to us in this consideration, 

 we may very properly note those only above freezing or the zero of the centi- 

 grade. "We have accordingly reduced the above Fahrenheit degrees to those' 

 of centigrade, and the series of temperatures for the respective months read as 

 follows : 



Now, if we consider the time at which the temperature of 4.5° centigrade or 

 40° Fahrenheit commences and terminates in each of these cities, and the sum 

 of the mean heat between these two limits, as shown in the above table, Ave 

 filiall find nearly the same result. At London the mean of 4.5° centigrade (40° 

 Fahrenheit) commences on the 17th of February and terminates on the 15th of 

 December. Between these two periods, we find by taking the monthly means 

 and fractious for the parts of the months named — that is, 5° centigrade for the 

 thirteen days of February, and 5° centigrade for the fifteen days of December, 

 which may be considered allowable since the heat of the latter part of February 

 and earlier part of December exceed the remaining portions, we find an aggre- 

 gate for Loudon of 115.50° centigrade. At Odessa the temperature of 4.5° 

 centigrade (40° Fahrenheit) commences later, from 2d to 3d of April, and termi- 

 nates sooner, from the 17tli to the 18th of November; but as it is warmer during 

 summer, the amount of heat determined as above is about equal to that of London, 

 being 116.39° centigrade. Hence it is apparent that a plant which would re- 

 quire 4.5° centigrade to commence vegetating with a certain activity, and in 

 order to reach a certain stage or condition would require in all an amount of 

 heat of 115° centigrade, rated upon the monthly means, might advance in a 

 northwest direction to London, and in a northeast to Odessa. If a plant should 

 require more or less than 4.5° centigrade as a minimum, or more or less than 

 115° centigrade in the whole as above calculated, the climates would no longer 

 correspond, and the limit of species would be otherwise established. Our author 

 has made use of the daily means in his calculation, and discovered that, a plant 

 commencing its growth at 4.5° centigrade, or 40° Fahrenheit, and requiring a 

 season extending to the return of the same temperature in autumn, would de- 

 mand at London 3,431° of centigrade heat, and at Odessa would receive between 

 the same minima 3,423° centigrade. The above is a much more accurate 

 method of comparison; but as we have not records of daily means for these 

 places at command, Ave have used the monthly means, Avhich, in this case, ap- 

 pear to approximate pretty nearly to the same result. It thus appears hoAv two 

 climates which difi'er, when considered as regards their respective mean monthly 

 temperature, may yet be identical under certain combinations of the tAVO causes, 

 which affect the life of the species existing therein. 



* The centigrade scale offers many facilities to calculation, and may be readily understood. 

 To convert Fahrenheit degrees, the common 'graduation, into centigrade, ob.serve the following 

 formula: x-^ Fahrenheit = (x° — 32°) | ceuiigrade, which means that to convert Fahrenheit 

 into centigrade, deduct thirty-two degrees therefrom, divide the remainder by nine, and mul- 

 tiply the quotient by five, for the amount in centigrade degrees. 



