different kinds of Dry Fogs. 231 



ing considerable capital, the poor inhabitants of these coun- 

 tries are obliged to prefer the former, which was introduced 

 into Germany in the eighteenth century. The peat is burnt 

 during seven or eight years ; it is then left at rest for a 

 period of from twenty to thirty years. Every year therefore 

 a quarter of the entire surface may be burnt. In the pre- 

 sent state of the population, it is about an eighth part, or 

 thirteen square myriametres, that is burnt annually. 



In order to sow buckwheat or oats, they turn up the soil 

 in autumn that the clods of earth and the vegetables they 

 contain may have time to dry during winter ; they are set 

 on fire in May, June, or July, according to the state of dry- 

 ness of the superficial soil. The burning continues for a 

 month, sometimes for fifteen days only. At certain spots it 

 continues throughout the whole summer. The carboniza- 

 tion of this peat, which is still humid, begins in the morn- 

 ing after the disappearance of the dew, and continues till 

 night. The cultivator takes care that the combustion does 

 not proceed too rapidly ; and there arises from it an extremely 

 thick smoke which forms clouds, at first insulated, but on 

 days when the fires are general, they unite towards the 

 middle of the day and form so dense a fog that nothing can 

 be distinguished at the distance of thirty metres. This 

 smoke rises above the highest mountains of the country — 

 that is to say, it exceeds a height of 650 metres. This im- 

 mense cloud of 430 square myriametres and 600 metres in 

 thickness, is driven by the east and north winds which pre- 

 vail at this period, towards the countries situate to the south 

 or west, where it darkens the air for whole days before 

 becoming dissipated in the atmosphere. Fincke estimates 

 the total weight of the carbonaceous particles thus raised 

 into the atmosphere in the course of one summer, at 900 

 kilogrammes. 



They are not satisfied with setting fire to the peat, but 

 likewise burn the turf and noxious plants. This practice is 

 followed in the neighbourhood of Siegen in Prussia, in Eifel 

 on the banks of the Rhine, and in England. M. Egen gives 

 proofs that the smoke arising from these burnings may ex- 

 tend very far. 



