METEOROLOGY OF THE LIBYAN DESERT.—A second volume of Gerhard Rohlfs' great expedition into the Libyan desert has been recently published at Cassel, under the editorship of Dr. W. Jordan of Karlsruhe, giving the detailed results of the researches of the expedition into the physical, geography and meteorology of this region during the winter of 1873—74. Though the observations extended only over a comparatively brief period, yet from their evidently high quality, the ability with which they have been discussed, and the physical characteristics of the region, the results thereby obtained form au exceedingly valuable contribution to meteorology. The results of the two-hourly observations show, as regards the daily maxima and minima of atmospheric pressure that the forenoon maximum and afternoon minimum are very greatly in excess of the others, and that the difference between them indicates an amplitude of range in accordance with that given for this region in Buchan's recently published charts of diurnal barometric range. The temperature has a daily range of 24°·5, the maximum occurring about 3 P.M., and the minimum a little before 6A.M. The lowest observed temperature was 23° in the earlier part of February. The minimum of vapour tension occurs about 6 A.M., and the maximum about 11 A.M. While the mean relative humidity at Cairo in winter is 65, it is only 51 in the desert, falling to 35, the minimum at 2 P.M., the dryness of the climate being thus very great. A humidity of only 17 was observed at Sandheim on February 12, at 2 P.M. Rain fell from February 1 to 4, thunder was heard on the second, and during next night 0.48 inch of rain fell, soaking the sand of the desert to a depth of about five inches—an amount of rain of rare occurrence in the district. The prevailing winds are north-westerly, those having the highest percentages being W. 16, N.W. 34, and N. 27, or 77 per cent. Warm springs occur in several of the oases, the highest observed being at Dachel, the temperature of which ranged from 92°·3 to 96°·8, or about 15° above the annual mean temperature of the locality. The magnetic declination was observed on January 1, at ten places variously situated between 25° 11′, and 29° 12′ lat. N., and 25° 31′ and 32° 34′ long. E. of Greenwich, the results of which, when compared with the observations of declination made in 1819–20 by Cailliaud indicates an annual variation of 6′·4, being closely approximate to that of Central Europe.