June 5, 1908] 



SCIENCE 



899 



an innovation in meteorological text-books, 

 dealing -with the importance of weather condi- 

 tions in practical life. Professor Kassner has 

 collected and classified a considerable number 

 of illustrations of the relation of weather con- 

 ditions to man's life, activities and health. 

 Many of these examples are not new to those 

 who have worked along the same lines, but the 

 collection of such illustrations will make them 

 ■widely useful. Professor Kassner has given 

 us a book which occupies a unique field. The 

 low price of the volume (1 Mark, 50 pf.) 

 brings it within reach of a large number of 

 persons. 



LAKE CHAD — ITS DESICCATION 



In a recent address entitled " From the 

 Niger to the Nile " (Scot. Geogr. Mag., Jan., 

 1908), Lieut. Boyd-Alexander noted the sup- 

 posed decrease in the area of Lake Chad. It 

 is his opinion that the lake does not alter 

 much in size, and that the supposed greater 

 original area is due partly to inaccurate 

 surveying and partly to the fact that certain 

 villages are several miles distant from the 

 lake, giving the impression that they were 

 formerly on the lake shore. The position of 

 these villages, Lieut. Boyd- Alexander believes, 

 is due to the danger of flooding during the 

 blowing of the Harmattan, which causes the 

 water to flow 600 yards over the land with an 

 ordinary wind, and drives it as far as two 

 miles when the wind is strong. Where there 

 are good banks, and where the water is not 

 influenced by the prevailing winds, there are 

 many villages close to the lake. A chain of 

 islands, once separate and now more or less 

 joined by a marsh, has also given the im- 

 pression of increasing aridity, but this change 

 may very likely be due to the silting of mud 

 and sand against the obstruction of the islands 

 by the opposing influences of the To and the 

 Shari, the two rivers that feed the lake. 



A EAILWAY WIND GAUGE 



Since September, 1903, a wind-gauge has 

 been set up near Ulverston, in England, to 

 protect trains from risk in crossing a very 

 exposed viaduct. The apparatus is flxed at 

 the west end of the Levens viaduct. Its 



actuating part consists of two boards, kept in 

 a vertical position by springs, and the move- 

 ments of which are shown on a chart by 

 means of the customary pen and clockwork 

 appliances. A pen is operated by either 

 board according to the direction of the wind, 

 and for gi-eater exactitude of time, the chart- 

 paper, over sixty-five feet long, is perforated, 

 the holes in the paper corresponding with 

 studs in the clockwork wheel. When the wind 

 pressure reaches 32 pounds to the square 

 foot the spring-boards referred to are adjusted 

 to make an electrical contact, ringing bells 

 in the signal cabins on either side of the 

 viaduct. When this occurs, all trains are de- 

 tained until the force of the wind moderates. 

 Any such interruption is telegraphed to the 

 superintendent of the line. In February, 

 1907, a velocity calculated as equivalent to 

 65 miles an hour was recorded. 



THE MOON AND CLOUDS 



J. E. Sutton, meteorologist of the De Beers 

 Consolidated Mines, at Kimberley, South 

 Africa, writes " On the Lunar Cloud-Period " 

 in the Trans. So. Afr. Philos. Soc, Vol. 

 XVIIL, Part 3, Dec, 1907. The cloud 

 observations at Kimberley have been worked 

 up for eighty-seven lunations, from January 

 1, 1900, to January 13, 1907. The inference 

 which the author thinks may fairly be drawn 

 from his results seems to be that if the 

 results " do not go far enough to prove that 

 there is a lunar influence over the clouds, they 

 do not prove that there is not. There are, at 

 any rate, a number of interesting coincidences 

 which seem to be worth elucidation." 



mountain SICKNESS 



In a recent paper on " Mountain Sickness 

 and its Probable Causes," by T. G. Longstaff 

 (Spottiswoode and Co.), the author gives ab- 

 stracts from the accounts of high mountain- 

 climbing expeditions, and includes the experi- 

 ences of aeronauts during high balloon 

 ascents, the results of experiments in pneu- 

 matic chambers, and his own observations. 

 He believes that mountain sickness is pro- 

 duced by (1) mountain lassitude, due to im- 

 perfect oxygenation, and (2) by excessive 

 fatigue and exhaustion. 



