1022 
large number of wood fires, which, 
though somewhat clumsier to handle, 
were none the less effective in obtain- 
ing the desired results, namely, saving 
the crops from damage. 
Types of Orchard Heaters 
In a commercial way, the types of 
pots used are the Fresno, Bolton and 
Hamilton. The Ideal coal pot was in use 
during the 1910 and 1911 frost periods. 
It is not the object of this article to dis- 
cuss the relative merits of the different 
types of pots. The writer, however, has 
contended that the simplest type, which 
of course, will be the least expensive, is 
the one which will grow in favor with 
the fruit growers. A lard pail type is 
just as efficient as the Fresno pot with 
its row of holes near the upper rim. The 
Bolton pot has one disadvantage with 
respect to the arrester, or partial cover, 
which is placed over the mouth of the 
pot. No doubt in burning 28-degree test 
distillate this type of pot will work very 
nicely, but with crude oil or slop distil- 
late the heavy coating of soot will tend 
to clog the openings and, in the course 
of a night’s use, will have a marked ef- 
fect in reducing the efficiency of the pot. 
It may even clog so much as to put out 
the flame. However, this pot, used open 
and without arrester, may be equal to 
the Fresno or lard pail type, and has 
proven so in actual test, since, burned 
Fig. 1. Hamilton Reservoir Type of Orchard 
Heater. 
that way, it is practically the same as 
the other two types. The Hamilton 
heater is so arranged as to increase or 
decrease the burning surface so as to 
regulate the amount of heat. ‘This pot, 
which is made in the form of a rectan- 
gular trough, is not so saving of fuel as 
might be supposed, since there is often 
a tendency for the flame to burn back of 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
the apron which hangs downward from 
the sliding cover, and which regulates, 
or is supposed to regulate, the amount 
of fuel burned. The Ideal coal heater is 
designed to hold 25 to 30 pounds of coal, 
and is very satisfactory so far as heat- 
ing is concerned, but the fact that a 
great deal of time is required to lay the 
fires, or prepare the heaters, is some- 
what against their use. There are a 
Fig. 2. Oil Stove Type. 
large number of heaters on the market, 
each one with its particular claim for 
efficiency; but as yet; with the fuels we 
have, it is a question as to what superi- 
ority one type may have over another. 
So far there has been no real efficiency 
test made in any part of the country 
where heaters have been used side by side 
under absolutely like conditions. It is 
the young orchard, which covers only a 
small part of the ground and traps lit- 
tle heat, with the fruiting area very 
low down near the ground, that is diffi- 
cult to protect from frost injury. A test 
in such an orchard would really be 
worth while. 
Fuels 
The fuels used are crude oil, 28-degree 
test distillate, coal, wood (old rails and 
cordwood), straw, sawdust and manure, 
the latter being mainly used to produce 
a dense smudge. One of the greatest 
difficulties in the use of crude oil and 
