284 



Progress in Science. 



[April, 



of Chili, Puerto Moult, Valdiera, and Conception ;" the second on Central 

 Chili, Santiago, and Valparaiso. 



We have already spoken of the contrast, as regards climate, between the eastern 

 and western extremities of the Straits of Magellan ; differences quite as remarkable 

 as these exist between the meteorological conditions of Patagonia and those of 

 Central Chili. On the southern part of the coast the glaciers, even in 46^° S., 

 come down to the sea, and the snow-line between 41 and 43 is at the level 

 of 6000 feet above the sea. Ten degrees further to the north the snow-line 

 rises to the level of 14,500 or 15,000 feet. Southern Chili and Patagonia are 

 among the wettest districts of the globe, while Central Chili is rainless for 

 seven months in the year, and its soil is at times a desert, unless where 

 irrigated. The Isotherm of 50 cuts the west coast of South America in about 

 the same latitude (south), as the corresponding Isotherm cuts the East Coast 

 of Asia and America in the Northern Hemisphere. The summer is on the 

 whole about io° or 15 cooler than that of corresponding places at the 

 other side of the equator, and the climate is, therefore, pre-eminently insular. 

 For Central Chili Dr. Hann gives us observations for Santiago and Valparaiso, 

 and bases his remarks chiefly on the accounts furnished by Gillis in the Report 

 of the United States Exploring Expedition. The climate is, on the whole, 

 subtropical, but excessively dry, excepting during the rainy season. Thunder- 

 storms are very rare and excite no less astonishment than earthquakes. The 

 range of temperature is moderate, much more so than in corresponding 

 latitudes in the Northern Hemisphere. The average temperature of Santiago 

 is 13 lower than that of Beirat. The low summer temperature on the coast 

 is due to the proximity of the cold water of the Humboldt current. 



Another paper is on " The Climate of Mesopotamia," based principally on 

 the observations of Dr. Schlafli and Lieut. Collingwood. This region is one 

 of the hottest in the world, as although it is in latitude 35 N. the Isotherm of 

 g5° passes over it in July. In summer, life in Bagdad is entirely regulated by 

 the temperature, for from 10 a.m. to 5 p.m. the heat above ground is unen- 

 durable, and the whole population descends into cellars called " surdabs." 

 On emerging from these in the evening the rooms and bazaars are still too hot 

 to be habitable, having been exposed to the sun all day long ; supper is 

 accordingly taken on the flat roofs of the houses, where everyone sleeps, in the 

 open air, without fear of injury, owing to the non-existence of dew. 



Raulin's paper on "The Rainfall of Algeria," which appeared in the " Comptes 

 Rendus," is also reproduced in abstract. 



Dr. Hann gives a notice of the remarkable phenomenon of increase of 

 temperature with the height, so well known in the Alps. He traces out the 

 actual fact very carefully, but does not attempt to assign a cause for it. 



Dr. Wojeikoff gives a most interesting note on " The Ice and the Water 

 Level of the Volga, in Relation to the Clearing of the Country," based on the 

 observations taken at Astrachan, for the years 1830-67. The following table 

 shows the means for the four nearly equal divisions of that period : — 



1830-37 



1838-47 

 1848-57 

 1858-67 



Froze. 



(») 

 Dec. 18 



» 14 

 ,, 22 

 „ 10 



Thawed. 



(b) 

 Mar. 22 

 » 23 



„ 26 



„ 29 



Flood 

 began. 



(c) 



Ap. 30 



,, 28 



» 29 



„ 22 



Highest 

 level. 



(d) 



June 16 



» 18 



,, 14 



>, 13 



Flood 

 ended. 



Greatest 

 depth of 

 water. 



Difference 

 in days. 



(/) Eng. ins. a-b b-c b-d c-f 



Aug. 17 104 94 3g 86 109 



,,31 90 g9 36 87 125 



Sept. 12 114 95 33 79 136 



Oct. 31 118 108 24 76 192 



Average 16 



25 



26 



15 Sept. 16 106 99 30 78 143 



The duration of the ice has somewhat increased, the river freezing earlier and 

 thawing later, but these changes are immaterial. The alteration in the time, 

 extent, and, above all, duration of the floods, is most striking. The fact that 

 the flood comes down eight days earlier is attributable to the great clearing of 

 the forests on the banks of the Volga itself, which has the effect of allowing 

 the snow to thaw sooner. The highest flood is noticed when the northern 



