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Show 154 1870 1871 1872 Fart Tuma. InchM. 2.71 0.78 3: 34 3.84 1870 1871 1872 1873 Fort Mohave, Inches. 3.07 2.01 3.02 . . . . . 3.04 If the rain- fall in the neighboring ranges had been measured, the results obtained would doubtless be three to four times as high. More than once did we see extensive rains in the mountains when not a drop fell in the adjacent valley, and were surprised on three occasions by heavy rains; once falling 1.06 inches of water in four hours. Sand- storms, hot winds, and whirlwinds, the latter producing columns of sand 100 to 200 feet high, are not infrequent, while they are quite rare in the coast counties. The hot wind ( simoon) is a most disagreeable feature; it continues sometimes until late at evening, with a temperature of 108° F. The sand- storms produce certain electrical phenomena; sparks were drawn by us one night from a blanket that was covered with a stratum of sand deposited by a sand- wind. Analogous to other deserts, the climate of the Mohave Desert is in summer time generally very hot and of great dryness. In connection with the latter, stand the great daily variations of temperature. In the annexed table are placed side by side some of our observations with those of Rohlfs made at Rhademes, an oasis iu the Sahara Desert, and a comparison will show how closely both climates agree. The highest temperature Rohlfs observed at Rhademes was 43°. 9 C. = 111° P., August 11, 1865. This was next to Shimmedru in the Oasis Kauar, the hottest place he struck in his travels through Africa; and at this locality he observed on a series of afternoons 53° C. = 127° F. At Mursuk, where he remained from November, 1865, to April, 1866, he observed as the highest temperature 36°. l C. = 96°. 9 P., ( March 12,1866.) According to Humboldt, the temperature of the Llanos of Caracas seldom rises above 98°. 6 F., although these plains are situated near the equator. The highest temperature our party observed in the Mohave Desert was 116° F., on the 6th of August, at Stone's Ferry, in the valley of the Colorado River in Southern Nevada. However, the temperature reaohes sometimes still higher limits. Mr. Jennings, who lived for nearly eight years at Saint Thomas, a small settlement on the Muddy, 24 miles from the Colorado, stated that in 1871 the thermometer rose in the shade every afternoon for three weeks in succession to 123° F., and on one occasion to 127° F. A temperature of 122° F. was also repeatedly observed at Fort Mohave. The temperature at night during the summer- months sinks frequently to 70° F., but does not fall often below 90° F., particularly when the air is in motion. The hottest portions of the Mohave Desert are the Coahui la Valley, ( altitude- 100 feet,) the Lower Virgin River Valley, ( altitude + 1,300 feet.) Death Valley, ( altitude- 200 ieet,) Panamint Valley, ( altitude + 1,400 feet,) the Saline Flats of the Mohave, ( altitude + 1,200 feet,) and the Colorado River Valley up to 1,200 feet altitude. While the four months June, July, August, and September are prominent by a very high tem- Eerature, the remaining eight months have a very moderate climate, and ice and snow ave been repeatedly seen on the Saline Flats of the Mohave in January. Warm winters, however, exist on the Lower Colorado and in Coahuila Valley, in which latter wild palms form an ornament of the oasis. As regards the mean temperature of the hottest months, it was calculated for Joly, 1873, in Fort Mohave to be 100°. 9 F., but for this calculation three observations served, taken at 7 a. m., 2 p. m., and 9 p. m. It is evident that the 7 a. m. observation is not a correct element in this calculation, as the temperature shortly before sunrise is considerably lower than at 7 a. m. We arrive clearly much nearer to the truth if the lowest temperature in 24 hours be introduced into the calculations of the mean. In July, 1873, were observed as the monthly means the following figures: 7 A. M. 12 M. 9 P. M. 91°. 4 F. 100°. 2 F. 98°. 7 F. If we take as the mean of the lowest temperatures admissible in July= 75° F., and calculate then the total monthly mean, we obtain 93°. 6 F., which stilf is a very high degree. * The mean temperature of the hottest month in- Degrees C. Degrees F. Cairo, Egypt 29.9 P5.8 Madras, India 31.8 89.2 Abushar, Persian Gulf 34 93.2 Llanos of Caracas 31.5 88.7 Shimmedru, Sahara 35 to36 95to96.8 Rhademes, Sahara 32.1 89.6 Ghadames, Sahara 32.4 90.3 Fort Mohave, Colorado River, Arizona 34.2 93.6 |