by which the bed of the river or canals, was elevated, 

 the currents retarded, in consequence of the diminish- 

 ed slope, and the delta extended ; but is it not proba- 

 ble that this source existed previous to the commence- 

 ment of the twelfth century, when the average annual 

 increase of the delta was only about ten feet and a 

 half? It may be said that the cultivation of the sur- 

 rounding country, at that period, was comparatively 

 small and limited, (which by the by is much doubted) 

 but admitting this to be the case, we will assume 

 the period of four hundred years, or in other words, 

 from the end of the twelfth century, to that of the 

 sixteenth. Is it probable that the increased culti- 

 vation of the neighbouring districts was such as to cause 

 an annual average increase of twenty-five metres, or 

 twenty-seven yards, one foot and one quarter of an 

 inch, (more than eighty- seven feet) when the annual 

 average increase, previous to the twelfth century, was 

 only ten feet and a half ? 



Or is it possible that it could have been such, dur- 

 ing the last two centuries, as to give an average in- 

 crease of extension, to the delta, of seventy metres, 

 equal to seventy-six yards, one foot seven inches and 

 a half, or two hundred twenty-nine feet, seven inches 

 and a half; a difference exceeding that of the preced- 

 ing period by one hundred and forty-one feet, five 

 inches annually ? To me it seems impossible. 



On the contrary, if we examine attentively the 

 causes which I have mentioned; the nature and source 

 of the materials, and the means employed in these 



