FKOST PROTECTION IIT LEMON ORCHARDS. 
3 
altitude of that portion of the mesa where these studies were made is 
about 1,000 feet. The mesa is protected on the south and east by 
the Santa Ana Range of mountains, having a general altitude of about 
4,000 feet. It faces the Santa Ana River valley to the north and 
west, and has an open and unobstructed exposure in these directions. 
Table I. — Climatological record of a lemon orchard near Corona, Calif., for the months 
of December, 1912, and January and February, 1913} 
December, 1912. 
January, 1913. 
February, 1913. 
Day of 
the 
month. 
Temperatures 
(°F.). 
Rainfall 
(inches). 
Notes. 
Temperatures 
Rainfall 
(inches). 
Notes. 
Temperatures 
Rainfall 
(inches). 
Notes. 
Maxi- 
mum. 
Mini- 
TTinm. 
Maxi- 
mum. 
Mini- 
mum. 
Maxi- 
mum. 
Mini- 
mum. 
1 
65 
60 
70 
67 
57 
57 
59 
65 
% 
66 
73 
72 
70 
66 
58 
75 
78 
75 
68 
59 
61 
68 
66 
62 
63 
69 
67 
67 
66 
64 
47 
43 
34 
34 
38 
38 
33 
41 
36 
34 
32 
41 
39 
32 
38 
32 
35 
48 
44 
45 
30 
44 
36 
33 
31 
42 
41 
31 
32 
33 
33 
74 
79 
83 
59 
55 
42 
52 
59 
48 
49 
54 
59 
68 
59 
58 
55 
56 
51 
58 
(^) 
64 
56 
65 
71 
77 
78 
76 
78 
72 
73 
78 
35 
47 
53 
32 
29 
19 
25 
25 
32 
32 
29 
29 
32 
32 
31 
42 
39 
34 
40 
35 
27 
30 
44 
44 
39 
40 
43 
40 
38 
47 
64 
66 
64 
64 
63 
70 
60 
59 
69 
69 
64 
71 
78 
73 
80 
76 
72 
65 
57 
57 
53 
55 
52 
54 
54 
54 
58 
63 
39 
41 
34 
34 
42 
47 
50 
% 
40 
39 
3S 
36 
39 
46 
41 
42 
40 
36 
29 
39 
38 
30 
33 
45 
35 
37 
32 
2 
3 
4 
e) 
e) 
(^) 
0) 
(3) 
(?) 
5 ... 
Trace. 
0.38 
.25 
.65 
6 
7 
8 
9 
10 
11 
12 
13 
14 
is:::::: 
0.05 
0.88 
.33 
.14 
16 
17 
18 
19 ... 
.28 
20 
(^) 
Trace. 
(5) 
21 
.... 
.32 
.50 
.15 
1.06 
.98 
.04 
.03 
22 
23 
24 
25 
26 ... 
27 

28 
29 
30 
31 
1 Records secured by Thos. C. Sias, weather ob- 
server for the Corona district. 
2^^^litef^ost. 
3 Violent north wind. 
* Violent north wind; minimum temperature on 
road alongside orchard at3a. m.,17'^ temperature 
did not reach 32° until 11 a. m. 
6 Missing. 
6 No damage, owing to clouds and high humidity. 
METHOD OF ORCHARD HEATING. 
Many of the lemon orchards in the Corona district were provided 
with orchard heaters for the protection of the trees and fruits during 
the low temperatures of December, 1912, and January, 1913. These 
heaters, for the most part, were oil burners of simple construction. 
The type of heater in most common use is shown in figure 2. The 
fuel used was a low grade of distillate. The heaters varied greatly 
in size, the smaller ones holding from 1 to 3 gallons of fuel each, while 
the larger ones each had a capacity of 7 to 9 gallons of oil. Some 
experimental heaters, having a much larger capacity and arranged 
