Fuel for Smudges. 118 
interruptedly from the hillsides, whence the cooled 
air flows down into the valley underneath the smoke 
and chills the plants. Damp straw, tar, turpentine, 
old hay, anything that will result in the greatest 
amount of smoke, will serve as fuel for these fires. 
Have the fuel on the ground in advance, and start 
the fires while the temperature is several degrees 
above the danger point. 
“It is believed that decidedly better results will 
be attained if damp fuel is used, or if the fire be 
sprayed with water, for this will add vapor to the 
air which, in condensing, will assist in checking 
radiation by obscuring the sky with fog or cloud, 
and at the same time the dew-point will be raised 
to the temperature of the air. This plan should 
result in absolutely preventing injury if the tem- 
perature be much above the danger point, for the 
condensation of the vapor will continue to distribute 
heat throughout the space occupied by the mist. 
In the case of smudge fires, the fire warms and 
expands the air near it, causing it to rise. This 
establishes an upward current of warm air from 
the fire, which conducts the heat of the fire upward 
and beyond the space needing protection, and cool 
air flows in from the sides to take its place. Thus 
the heat of the fire has but little effect in dimin- 
ishing the intensity of the frost, almost the entire 
protection being gained by the blanket of smoke 
produced. By spraying the fire, on the other hand, 
a large portion of the heat of the fire is consumed 
in evaporating the water which, rising from the 
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