i88i.] Weather -Wisdom and the Harvest. 5 73 
be remembered, however, that the grass is fed into that part 
of the machine which receives the hot air diredlly from the 
furnace, and as it becomes drier it travels gradually on to 
the cooler parts of the machine. (See drawing.) Hence if a 
spark flies up from the burning fuel it is at once extinguished 
by the green matter with which it comes in contact, and 
which thus protects the drier portions. In practical working 
no disaster from this or any other cause has ever arisen. 
But this primary principle, the passage of the furnace 
produ( 5 ts through the hay itself, would have been very in- 
efficient without the mechanical arrangements by which the 
