THE DRIFTING OF THE CONTINENTS TERMIER 231 



Note that 2.9, or rather 3, is the density of solid and crystallized 

 basalt at the surface of the globe; the density at this same surface 

 of fluid basalt, of flowing basaltic lava, is indeed less; and the den- 

 sity of this basaltic fluid certainly varies with the pressure to an 

 extent unknown. So that the calculation of the ratio of the plunged 

 and submerged depths of sal seems a little illusory. How to admit 

 finally that in a bath of sima of such mobility, in a bath where the 

 great blocks of sal float and drift, the tides determined by solar and 

 lunar attraction may not be sufficiently energetic to break each day 

 the thin pellicle which separates the molten sima from the oceanic 

 waters? For it is indeed necessary that this pellicle be very thin, 

 otherwise it would imprison forever the continents it incloses. 



But in the matter of geological hypothesis the improbabilities do 

 not count. They do not prove that a theory may be radically 

 false; they simply show that it needs to be ameliorated, corrected, 

 accurately stated. If one does not accept the theory of Wegener, 

 it is not because there are others fully satisfactory. Thus far none 

 has been proposed which does not also show some striking im- 

 probabilities. Between these theories, which displace the enigmas 

 without solving them, we choose according to our tastes and tem- 

 peraments, some finding acceptable those which others declare 

 absurd, unless we should prefer to take refuge in a kind of scientific 

 agnosticism. In truth there are geological phenomena themselves 

 astonishing and improbable, of the existence of which one is entirely 

 certain. How, henceforth, expect to explain them? We know 

 that the lithosphere moves, that its movements have periodic returns, 

 that certain of them are oscillatory; we also know, or think we do, 

 the extent of their amplitude. That is all. Of the profound causes 

 of this mobility, of the manner in which the movements begin, 

 progress, and cease, we know nothing. 



To ameliorate Wegener's theory and render it lasting, to do away 

 with the gross improbabilities of which I have spoken, we can trust 

 to the geo-physicists. They will conceive by new hypotheses other 

 details of the "machine," as Pascal remarks, details which perhaps 

 will not be more correct than the first and which, in any case, 

 ■will not be more possible of verification. 



Some days ago, in a communication which I had the pleasure of 

 presenting to the Academy of Sciences, my excellent friend, Emile 

 Belot, with whose original and bold ideas you are acquainted and 

 ■whose cosmogonic theory has interested Henri Poincare himself, 

 recalled that, long before Wegener, he had attempted to explain in 

 :an entirely different manner the genesis of the continents and the 

 oceans; and he showed how his own theory accounted for the 

 original grouping of the continents in a single mass, a grouping 



