Practical Geometry in Egi/pt. 339 



was then only that the Greeks could profit by the advances 

 which the Egyptians had made ; and that Thales and Pytha- 

 goras, and perhaps several other sages whose names have not 

 been preserved, went to be instructed in the school of the 

 priests. 



To judge of what the Greeks must have gained by this com- 

 munication, it is necessary to know what was at this period the 

 state of knowledge in Egypt. Let us, in the first place, look to 

 the mathematical sciences. 



It is certain that the Egyptians had a knowledge of hydrau- 

 lics, as they were expert in the art of digging canals ; that they 

 had ideas of mechanics, since, without very powerful machines, 

 it would have been impossible for them to erect obelisks, and to 

 raise the enormous blocks which some of their monuments pre- 

 sent. It is certain that they had tolerably perfect modes of 

 procedure in stereometry, of which a proof is given in the cut- 

 ting of the stones of their buildings. We know, further, that 

 they were good surveyors. All this would lead us to believe 

 that they were pretty well advanced in the mathematical theo- 

 ries. But, on the other hand, if it be true that it was only 

 after his travels that Pythagoras discovered the theorem of the 

 square of the hypothenuse, it must be admitted that the geo- 

 metry of the Egyptians was still in its infancy, or, at least, that 

 it was purely practical. 



At the period when the first migrations were made to Greece, 

 astronomy was very little advanced in Egypt, as the lunar year 

 alone was known. But as this science, as we have said, was 

 very necessary to the Egyptians, they devoted themselves to it 

 with great application, and made rapid progress in it ; so that, 

 when a communication was re-established with the Greeks, in 

 the reign of Psammeticus, they had already adopted the solar 

 year of 365 complete days. Soon after, they made the addition 

 of a fourth of a day, and thus came much nearer the true dura- 

 tion. This reformed solar year was employed for civil uses. 

 As to the religious year, having been regulated at an earlier 

 periotl, it remained with its 365 complete days, without its 

 being allowed to change it. It happened, in consequence, that 

 the festivals were gradually displaced — that they no longer cor- 



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