Oti the Arabian Frontier of Egypt. 211 



had been virtually effected, would be carrying scepticism be- 

 yond reasonable bounds. Some later historians than Hero- 

 dotus certainly do seem to treat of it as not finished by Da- 

 rius ; but where we find conflicting accounts of a matter of 

 fact, we must estimate the authority of a witness according 

 to his means of information, weigh it with other facts, and 

 decide accordingly. The subsequent retiring of the sea will 

 prove the means of harmonizing the discrepancies their ac- 

 counts exhibit ; and as the sequel will shew how the mistake 

 of the ancient authors here adverted to, finds an easy and na- 

 tural explanation by this hypothesis, we may, for the present, 

 safely admit the distinct statement of Herodotus — that the 

 canal in his time was finished up to the sea — as an histori- 

 cal fact, and a fixed point to start from in the succeeding in- 

 quiry. 



We must now revert to the configuration of the district 

 along which this famous canal was led, and convince our- 

 selves, by a critical analysis of its external features, that, al- 

 though we have, on the one hand, this positive historical 

 fact, that Darius joined the Nile to the Arabian Gulf, we 

 have, on the other hand, an equally positive physical fact, 

 that to do this, without intercepting the northern half of the 

 river, would have been impossible ; — as impossible as for 

 Necho to have made his canal along the valley of Etham, 

 without first intercepting the southern half. 



Every body knows that if water runs off" down a slope to a 

 much lower level, the general level of the water will corre- 

 spond with that slope, and therefore its height, at the end 

 of its course, will be about as much less than that of the ori- 

 ginal fountain, as the amount of the incline downwards.* But 

 if, instead of being thus allowed to run off, the course of the 

 water is dammed up, then the water-line will no longer cor- 

 respond with the slope — it will rise to the level of the origi- 

 nal fountain, and become horizontal. t 



When the waters rose to 4 feet 6 inches above the bed 

 of the ancient canal, and within 3 feet 9 inches 9 lines of the 

 top of the granite block at Moukfar, during the irruption of 



* Vide I'lutft VI., diagram IJ, linfi AHB. t H/ul., lino AA. 



