A farther illustration is given in the subjoined table, showing maxima and minima of monthly evaporation, as well the totals of one (seasonal) year, in three California localities where the air-saturation is considerably below that at Berkeley, ranging in summer from 50% to 20% and even less (at Calexico in the Colorado desert): SUMMARY OF EVAPORATION-LOSSES FROM WATER-SURFACES, AT POMONA, TULARE, AND CALEXICO, CAL., FROM JULY 1, 1903, TO JULY 31, 1904. ============+=================+=================+================= | Pomona. | Tulare. | Calexico. +---------+-------+---------+-------+---------+------- | Month. |Inches.| Month. |Inches.| Month. |Inches. ------------+---------+-------+---------+-------+---------+------- Maximum |Aug. 1903| 9.07 |July 1903| 12.34 |July 1903| 14.48 Minimum |Feb. 1904| 2.57 |Jan. 1904| 1.46 |Jan. 1904| 4.39 | | ----- | | ----- | | ------ Totals for | | 66.92 | | 74.68 | | 108.23 year | | | | | | ------------+---------+-------+---------+-------+---------+------- Of these three stations, Pomona is located within reach of the ocean winds, but distant 25 to 30 miles from the shore. Tulare is situated in the upper San Joaquin valley, far in the interior; Calexico is in the southern part of the Colorado desert, with extremes of temperature ranging from 13° Fahr. in winter to 120° in summer. _Evaporation in Different Climates._—The following table conveys some general data regarding average evaporation from water-surfaces in different climates. Evaporation from the soil-surface depends largely, of course, upon the mechanical condition of the surface, the extent to which it is wetted, and the rapidity with which moisture will be supplied from the subsoil as the surface dries. A field plowed into rough furrows will evaporate more water than when harrowed, because of the larger surface exposed; and a harrowed field moderately compacted by rolling will lose less water by evaporation than when unrolled, other things being equal. On the other hand, a thoroughly compacted surface, even if suffering less loss at first than a plowed or harrowed field, will continue to lose moisture longer by withdrawing it from the substrata by its superior capillary suction; while a loose surface, once dried out, will prevent farther loss from the subsoil very effectually, as stated below.