542 



SCIEXCE. 



[Vol. VII., No. 176 



present anomalous condition of the silver coinage, 

 but even to take any rational measures for finding 

 out what ought to be done in the case, is another 

 subject on which their views would be of interest. 

 I cannot help thinking, if they would grapple 

 with these practical difficulties, and tell us what 

 wise and good legislation they expect to get 

 through congress, they would be more effective 

 than they are in confining themselves to discus- 

 sions on which no effective issue can be joined. 



S. Newcomb. 



FLOODING THE SAHARA. 



Much misinformation has of late been spread 

 abroad respecting ' the proposed interior sea of 

 Africa,' and the public has been misled by inac- 

 curate statements in regard to the magnitude of 

 the enterprise, which, it is assumed, the French 

 people are about to undertake. For these cur- 

 rent eiToneous impressions the English and Amer- 

 ican scientific journals are largely to blame. An 

 old theory regarding the Sahara — that it was for 

 the most part below the level of the ocean — has 

 been adopted as though modern surveys had not 

 refuted it : and so the conversion of a material 

 portion of the African continent into a navigable 

 sea is being popularly considered as not only pos- 

 sible, but altogether likely to be accomplished. 



A brief consideration of the published results 

 of the recent surveys will be sufficient to convince 

 the reader that the popular estimate of the mag- 

 nitude of this enterprise is absurdly out of pro- 

 portion to the greatest possible accomplishment. 



This overestimate is not surprising when we con- 

 sider the character of the references to the scheme 

 which have been made by journals of the best 

 standing. The following paragraph from the 

 foremost among engineering journals may be 

 taken as a sample : — 



"With reference to the daring French project 

 for flooding the desert of Sahara with what would 

 be virtually a new sea, it may be well to recall the 

 opinion expressed by M. Elisee Reclus, that at one 

 period in the world's history the desert was 

 covered by a sea very similar to the Mediterranean, 

 and that this sea exercised a very great influence 

 upon the temperature of Fiance, as comparatively 

 cold — or, at any rate, cool — winds blew over it, 

 while now the winds which prevail in the great 

 expanse are of a much higher temperature, and 

 are, in fact, sometimes suffocatingly hot. The 

 appearance of the desert seems to support the 

 theory of M. Elisee Reclus. that it was at one 

 time the bed of a sea of considerable extent, of 

 which the great inland African lakes recently dis- 

 covered are possibly the remains. The present 



vast extent and configuration of the African con- 

 tinent would also appear to support the conclusion 

 that at one time it comprised a less area of land 

 than it does at present. The serious question 

 which arises, assuming that the theory of M. 

 Elisee Reclus is substantially correct, is, What 

 will be the effect of the creation of a second 

 African sea in the room of that which has disap- 

 peared ? Would the temperature of France, and 

 possibly even of England, be again reduced ? It 

 is a geological theory that in the glacial -period of 

 the world's history Great Britain was covered with 

 ice and snow very much as Greenland is at pres- 

 ent. Some great influences must clearly have 

 been brought to bear upon France and Great 

 Britain, which rolled the ice over so many hundred 

 miles northward. What was this influence ? Was 

 it the large African sea which French enterprise 

 is endeavoring to recreate? If it were, we should 

 say that whatever the French may gain in Africa 

 by the realization of a Saharan Sea would be much 

 more than counterbalanced by what they would 

 lose in France itself." 



A writer in another journal suggests that all na- 

 tions interested in the commerce of the Mediter- 

 ranean may by right protest against the execution 

 of a scheme that would produce a troublesome 

 current through the Straits of Gibraltar. And the 

 same writer, furthermore, adds, " So much water 

 drawn from the present oceans, may, by lessening 

 the depths of the harbors of the world, produce 

 serious and wide-spread inconvenience." 



That all such fears are utterly groundless is 

 abundantly shown by the results of the careful 

 surveys made within the last few years. A brief 

 resume of these results is presented below. The 

 figures are reduced from the metric measures in 

 ' Nouvelle geographie universelle,' by Reclus, and 

 the maps from ' Le genie civil.' In both cases the 

 authority quoted is the French engineer, M. Rou- 

 daire. 



Every one who, as a student, has had to draw 

 the map of Africa, can certainly recall that singu- 

 lar interruption to the otherwise regular coast-line 

 on the extreme northern boundary, where the 

 coast, for a comparatively short distance, has a 

 general north and south trend. This notch marks 

 the north-eastern terminus of the Atlas mountain 

 system. The eastern shore is the eastern bound- 

 ary of Tunis ; and on it, in ancient times, stood 

 Carthage. An indentation at the southern part 

 is called the Gulf of Gabes. 



A line extending due west from the shore of 

 this gulf crosses a barren region, of no interest 

 but for the project about which this article is writ- 

 ten. It is a region abounding in basin-shaped de- 

 pressions, containing either shallow salt-marshes* 



