114 The Principles of Fruit-growing. 
fire, is quickly condensed as it comes in contact 
with the surrounding air. The heat of condensation 
thus becomes manifest in the lower air. The heat 
of the fire is thus in a measure trapped and dis- 
tributed throughout the lower stratum of the air, 
and greatly aids in protecting the plants. Every 
quart of water thus evaporated and again con- 
densed in the surrounding air would be sufficient 
to raise the temperature ten degrees throughout a 
space eighty feet square and deep.” 
Smudges have long been used in the vineyards 
of parts of Europe. <A sketch of some of the 
practices may add to the interest of this discussion.* 
“Protection from frost is often secured by the use 
of smudges, namely, piles or bundles of such stuff 
as will produce a great smoke while burning. They 
are placed around the field and lghted at the ap- 
proach of frost, and the smoke which arises from 
trees hanging over the fields, will, after the man- 
ner of clouds, tend to keep the escaping heat near 
the earth. Pliny is said to have recommended the 
practice, and as early as the sixteenth century it 
was advised by the great French agriculturist, Olivier 
de Serres, who wrote: ‘Frost is repelled from the 
vine if, foreseeing it, you produce in various parts 
of your vineyard thick smokes by means of wet 
straw or half-rotten manures. These sunder the air 
and dissolve the nuisance. * * * * Prepare 
them in good season by building here and there in 
your fields little piles of the above mentioned matters, 
* Prepared by my student, W.S. Andrews, B. A. 
