318 
Agriculttiral Meteorology. 
matter how rude, to procure the necessary shelter, and their 
annual maintenance, would militate against any rapid expansion 
of this branch of agricultural enterprise in Germany. While in 
the British islands stock of all kinds, save when fatting, lambing, 
or in milk, may be said to endure the ordinary vicissitudes of our 
seasons without inconvenience. 
These extremes are not limited to Germany, or what is called 
the north of Europe. France, Piedmont, and Lombardy expe- 
rience, though for a shorter time than England, over large por- 
tions of their superficies, degrees of cold equal to that which has 
been noted on this side the Channel. Their winter is brighter 
and drier than ours, and so far more favourable in some respects 
to vegetation, and, with particular constitutions, it may be, to 
bodily health. Their days are longer, between the autumnal and 
the vernal equinoxes, than ours ; but, away from the sea-coasts 
and out of the reach of the modifying influence of the maritime 
air, far greater deviations from the mean, both of heat in summer * 
and of cold in winter, are to be met and provided for. 
The average temperature, however, of each season, as measured 
by the thermometer, does not appear to be the only condition 
which determines the growth and maturity of vegetation. 
M. Gasparin endeavours ingeniously, but not with perfect 
success, to substantiate and define the theory propounded by his 
countryman, M. Boussingault, with regard to the quantum of 
caloric required by certain plants to arrive at maturity. Boussin- 
gault's position is that wheat requires 2000 degrees of atmospheric 
heat (chaleur moyenne). Centigrade, from the time when it 
resumes its growth in the spring until it is fit for the sickle. It 
is not, at first sight, easy to translate this measure of caloric into 
such a description as will render it intelligible at a glance to the 
English reader, who is accustomed to the Fahrenheit scale. It 
appears, however, to import in substance, that the mean tempera- 
ture of the period or periods elapsing between the first movement 
of the sap in spring and the ripening of its grain, when multi- 
plied into the number of days, should present such an amount of 
heat as to equal 2000 degrees of the Centigrade ; so that, sup- 
posing four months to intervene, it would require that the average 
temperature (solar and atmospheric) of each day should be 16 7° 
* At Paris the average number of frosts, according to M. Chr. Martins, 
is 56 ; in the winter of 1812 there were 91 ; in that of 1838, 74; in 18-10 
as many. The greatest cold of late years was on the 20th of January, 
1838, when the thermometer sunk to 2-2' below zero, Fahrenheit. In 
the department of the Ain it was more severe, going down to 13^ below 
zero, Fahr. : all the mulberries were killed. Even at Orange, in 1820, the 
mercury mai ked 8-6^ Fahr. on the 1 1th of January ; on the 15th a sudden 
thaw occurred, which was fatal to the olives in Provence. In the years 
1745, 1748, 1766, and 1802, with a frost of 6 8^ Fahrenheit, no ill results 
followed, where the trees had the benefit of a free current of air. 
