SCIENTIFIC AGRICULTURE. 

 HAIL. 



Hail is a well known meteor, which occurs most commonly 

 in spring and summer, and is often accompanied with thunder. 

 It is formed by the congelation of rain or vapor in the upper 

 regions of the atmosphere. Hail storms are of rare occurrence, 

 and seldom continue more than a quarter of an hour. Hail 

 clouds always float lower than rain clouds. Hail stones appear 

 to be composed of several spherules adhered together; those 

 of the centre being soft, sometimes nearly fluid water, and 

 those of the circumference solid and opake. 



They are also occasionally laminated or radiated. Hail 

 stones are sometimes enormously large : the largest of which 

 we have seen any account, according to Dr. Brande, measured 

 14 inches in circumference, and weighed from 5 to 13 ounces. 

 Many ingenious speculations have been made to account for 

 the formation of hail, but none of them sufficiently satisfactory 

 to be entitled to implicit belief. The most probable cause of 

 this phenomenon now is, that " hail is produced by the mixture 

 of exceedingly cold air with a body of hot and humid air." 



[Olmstead. 



Whether a cold wind comes suddenly from the regions of 

 perpetual congelation, in contact with a body of hot air charged 

 with vapor, blows suddenly into the regions of perpetual frost, 

 and thus, by condensation of the vapor, produces hail, we can- 

 not determine. It is sufficient for this theory, that hot moist 

 air meets with intensely cold air in any way whatever. 



LIGHTNING. 



" This is an electric phenomenon produced by the passage 

 of electricity between one cloud and another, or between a 

 cloud and the earth." The zigzag form of the flash, the fre- 

 quency of its repetition, and the great length, or extent of sky 

 which it embraces, are not yet well understood or accounted 

 for. 



