34 CULTURE OF THE SUGAR BEET. 



course, of importance to note whether the temperature is sufficiently 

 high to insure the development of the plant, and, after this, note must 

 be taken of the rainfall with which the section is favored during each 

 month. It is not sufficient to know that the quantity is equal to or 

 above a certain average, but that it be regularly supplied, and also that 

 the temperature is not sufficiently high to evaporate it before it can be 

 made use of by the plant. In this study, therefore, it is desirable that 

 we take into consideration as factors the average temperature, rainfall, 

 humidity, and number of rainy days for each month during the growing 

 season. 



Upon consulting the map of the European states showing the location 

 of beet-root culture, we find it generally concentrated toward the north. 

 But, in the study of the meteorological conditions, we find that the quan- 

 tity of rainfall during the year is greater in the south than in the north, 

 and yet in the former section vegetation seems to suffer more from want 

 of moisture than in the latter. Marie Davy justly explains this by re- 

 ferring it to the evaporation due to a higher temperature, more direct 

 sunlight, and a less number of days upon which rain falls. Thus he 

 says : * 



Generally, raine are less numerous, more abundant, and less disseminated in the 

 south thau in the north. It rains longer and more frequently in the neighborhood of the 

 coasts than in the interior; and, finally, mountains are a cause of increase in the to- 

 tal annual rainfall, especially upon sides exposed to -winds from the sea. The sovith 

 of France, therefore, receives more of water in rains than the north, but the rains are 

 less frequent. The temperature being higher, the atmosphere contains more of aque - 

 •ous vapor, with equal degrees of the hygrometer, and, when the condensation of moist- 

 ure takes place, it furnishes a larger quantity. But the condensations are more rare, 

 and, as the evaporation is very active, the periods of drought are long and sometimes 

 very intense. Sections bordering on the ocean and the channel are more frequently 

 rainy than the interior. * * * The French coast of the Mediterranean forms an 

 ■exception to this rule. Here the annual rainfall is but 0.60 meter (23.6 inches) not- 

 withstanding their southern position. This is because the rainy winds of the center of 

 France reach the basin of the Mediterranean only after passing the Cevennes Mount- 

 .ains, where they lose the greater portion of their water. 



Concerning evaporation the same writer says:t 



It is the reverse of rainfall. This phenomenon varies widely according to times and 



places. If we consider first the annual average by regions, we obtain the results 



summed up below: 



Inches. 



Plains of the north of France - 24.4 



Plains of the west of France 26.7 



Plateau of the central region . 34.25 



Southern France 8T.79 



Whether these relations be the sole influence tending to confine the 

 beet culture of France to the limits mentioned above or not, it will be of 

 interest to see what are the conditions most suitable to the culture as de- 

 termined by observation, and what are the conditions recorded for the 



* Meteorologie et Physique agricoles, Paris, 1675, p. 190. tlbid, p. 193. 



