468 Best Way with Freezes. 
tective measures fail when the temperature falls a few degrees 
below 28° or when such freezing temperature is continued sev- 
eral hours. During the last few years, at Riverside, systematic 
invention and trial of frost prevention has proceeded, and the 
most satisfactory results are thus described by E. W. Holmes :— 
Satisfactory results have been gained by the use of soft coal, burned 
in wire baskets suspended under or between the trees. When twenty 
to forty of these to the acre were used, we occasionally raised the tem- 
perature from three to five degrees. More has been claimed; but this 
is all that I am sure has been achieved. However, in a section where 
the temperature would not go below twenty-five or twenty-six degrees. 
for a few hours, this method was ample. The outfit costs about ten 
cents a basket, or four dollars an acre if forty baskets are used, and the 
coal about two and one-half dollars an acre per night. The objection 
is the labor of replenishing the baskets in case of their being used the 
second night, because even if kerosene is poured upon the kindling, it is 
no easy task to light four hundred fires with a torch. Four.men will 
be required to do this in proper time. Still. this is the system more 
generally approved here, and because definite and certain results have 
been achieved through it. 
This refers to the protection of citrus fruits, the value of 
which as the crop is maturing will warrant the cost. With de- 
ciduous fruits thus far only smoke and steam clouds from burn- 
ing piles of damp rubbish have been employed, except in irn- 
gated regions where, if the frost threatens while the ground is 
dry, the limited efficacy of running water is resorted to. There 
is ample field for farther experiment in all lines of frost pre- 
vention. 
Where there is trouble from early activity of deciduous trees 
the trees may be kept dormant for a limited time by winter 
spraying with whitewash, which reflects heat and thus prevents 
» -activity. Experiment has shown that heat upon the aerial parts 
of the tree start the growth; it does not come from the root as 
was formerly supposed. 
