320 THE VALLEY OF THE THIELE. 



the years 1090 and 1106, and is therefore about 750 years old. 

 It is possible that the abbey may not have been built exactly 

 on the then edge of the lake ; but even if this were the case, 

 the gain of land will only have been 375 metres in 750 years. 

 Prof. Gillie*ron does not compare with this the whole space 

 between the convent and the Lake- dwelling, because in the 

 narrower part of the valley in which the latter is situated, 

 the gain may have been more rapid ; but if we only go to the 

 point at which the basin contracts, we shall have a distance 

 of 3,000 metres, which would upon these data indicate a mini- 

 mum antiquity of 6,750 years. This calculation assumes that 

 the shape of the bottom of the valley was originally uniform. 

 M. Morlot agrees with Prof. Gillieron in believing that 

 this was the case, and from the general configuration of the 

 valley it seems to me also to be a reasonable supposition. 

 Moreover, the soundings taken by M. Hisely in the Lake of 

 Bienne show that the variations in depth are but of slight 

 importance. These two calculations, then, appear to indi- 

 cate that 6,000 or 7,000 years ago Switzerland was already 

 inhabited by men who used polished stone implements, 

 but how long they had been there, or how many cen- 

 turies elapsed before the discovery of metal, we have as yet 

 no evidence to show. 



A still greater antiquity is obtained by Mr. Horner as the 

 result of his Egyptian researches, which were undertaken at 

 the joint expense of the Royal Society and the Egyptian 

 government. It is well known that the valley of the Nile is 

 overflowed every year, and even as long ago as the time of 

 Herodotus it was inferred that Egypt had been formerly 

 an arm of the sea, filled up gradually and converted into dry 

 land by the mud brought down from the upper country. 



In the great work on Egypt, which we owe to the French 

 philosophers who accompanied Napoleon's expedition to that 

 country, an attempt was made to estimate the secular 



