For a better personal appreciation of the rate of evaporation, as well as for the purpose of comparison, I arranged an apparatus to tell the water-loss from a free water-surface. It was also desirable to determine the relative evaporation of the day and night. As employed, the apparatus consisted of a flat tin dish, with parallel sides, 10 cm. in diameter. To the side was attached, by means of a rubber stopper, a bent glass tube of small diameter. The water-loss was read on this tube. Observations were made at Laghouat and at Ghardaia. Following is a summary of the results obtained at Ghardaia: For a period of 7 days, after November 10, the daily water-loss between 7 a.m. and 7 p.m. was as follows: 5, 8, 8.5, 10.5, 13, 9, and 7.5 mm. The evaporation between 7 p.m. and 7 a.m. was so slight, 1 mm. more or less, that it could not be well determined by the apparatus used. A good idea of the intensely arid character of the Algerian climate, taken as a whole, is to be obtained by a study of the relation between the total rainfall and the total evaporation, based on the official climatic reports. In tables 6 and 7 the report for the year 1908 is used. The figures represent the ratio (_e_/_r_) between evaporation and rainfall, in which the amount of evaporation is used as the numerator and the amount of precipitation as the denominator. In the monthly evaporation-rainfall table (table 6), in all cases where no rainfall was reported for the month it was called 1 mm. In table 7, however, which gives the seasonal evaporation-rainfall ratio, the actual figures of the government report were in all cases employed, since there was no season during the year 1908, even in southern Algeria, when no precipitation occurred.[6] TABLE 6.—_Evaporation-rainfall ratio, monthly_, 1908.