Natural History. 207 



hay with all its natural verdure. To obtain this effect, the grass, 

 as soon as cut, is (without being allowed to fade) instantly 

 stacked. A kind of chimney, made with four rough boards, is con- 

 structed in the middle of the stack, and it appears that this channel 

 prevents the accumulation of heat from fermentation ; and that the 

 herb thus treated retains all its leaves, its colour, and its primitive 

 taste. The size of the stacks is not mentioned *. 



12. REMARKABLE PROPAGATION OF WIND. 



Whilst the bells were ringing to church, at Albany, on the 12th of 

 July, 1829, a very violent gust of wind from the south-east passed 

 over the town. This gust passed over New York, which is to the 

 south of Albany, when the service had proceeded for some time: 

 so that this south wind was rendered evident in the northern town 

 an hour nearly before it was felt at the southern position, and it 

 had been propagated from north to south in the direction exactly 

 contrary to that in which it blew. 



Franklin remarked that violent north-west winds in the United 

 States frequently had their origin in the quarter towards which they 

 passed, and was inclined to attribute them to great and sudden 

 alterations in the atmosphere of the Gulf of Mexico. To explain 

 the present instance in the same manner, a diminution in the atmos- 

 pheric pressure to the north of Albany must be considered as 

 having occurred f. 



13. THOUGHTS ON NORTH AND SOUTH WINDS. (By M. Alphome 



Blanc.) 



It has been generally admitted that winds are mostly, if not always, 

 caused by dilatations or condensations of the air due to changes of 

 temperature. In fine, quiet weather, the wind from the east in the 

 morning, often becomes south at midday, and west in the evening, 

 and may, with great appearance of reason, be attributed to the 

 dilatation of the air by the sun in the east, south, and west in 

 succession, of the place of observation. It is also known that a 

 wind often blows in one place before it blows in another place to 

 windward of the first ; and in such cases it has been supposed that 

 the effect is due to some great condensation in the air at some place 

 to leeward of the place where the wind is felt. 



Now the barometer should be affected differently according to 

 the nature of the cause of wind. If condensation occurred about 

 the pole, the air of surrounding places should flow towards it, a par- 

 tial vacuum should occur in those places, forming a south wind 

 gradually extending towards the south, and the others to which the 

 wind should reach, and the barometer should fall at those places. 

 But if expansion of the northern air occurred, a north wind should 

 commence at the north, and be propagated to the south, driving or 

 accumulating the air before it, and the barometer should rise in all 

 those places to which it reached. 



* Recueil Inclust., xv, 247. f Ann, de Chimie, xlv, 420. 



