ANNIVERSARY ADDRESS OF THE PRESIDENT. XCIX 



tolerable uniformity of character, we should be justified in holding 

 that the portion of change that had taken place within the historical 

 period would afford a measure of the time occupied in the production 

 of the antecedent part of the same change. Egypt appears to Mr. 

 Horner to be the only land of all parts of the world as yet known to 

 us that offers an instance of a great geological change that has been 

 in progress throughout the whole of the historical period down to 

 the present day, and which we have reasonable grounds for believing 

 had been going on with the same uniformity for ages prior to the 

 period when our reckoning of historical time begins. This is owing to 

 the annual inundation of the Nile, and the sediment that falls from its 

 waters on the surface of the land it overflows. The historical monu- 

 ments of Egypt are the oldest in the world, and afford the most ac- 

 curate records of the earliest period of the human race in which any 

 trace of civilization has been discovered, combined with records scarcely 

 less accurate of geological changes contemporaneous with history, 

 and having such a degree of uniformity as to warrant us in carrying 

 back the dates of changes of a like nature beyond that of the earliest 

 historical documents. 



With these views Mr. Homer determined to endeavour to in- 

 vestigate the formation of the alluvial land in the valley of the Nile 

 in Upper and Lower Egypt, comparing the depth of sediment which 

 has accumulated to a considerable height above the base of the 

 oldest works of art near the Nile with the sediment deposited below 

 the base of these same monuments on the rock forming the bottom of 

 the channel. If, he observes, the depth of sediment above the base 

 of these works of art be divided by the number of centuries that have 

 elapsed since the date of their erection, we may obtain a measure of 

 the secular increase of the sediment ; requiring, however, a correction 

 for causes that might make a difference in the rate of increase be- 

 tween earlier and later periods. 



Having thus fully stated his object, Mr. Horner commences his 

 inquiry with an account of the physical geography and geological 

 structure of Egypt, an account of the inundations of the Nile, and 

 of the solid matter conveyed by the Nile to form its sedimentary de- 

 posits, and then proceeds to describe the recent researches undertaken 

 at his suggestion. These embrace an account of the excavations at 

 Heliopolis, descriptions and analyses of the soils, descriptions of the 

 several pits and shafts sunk, and a synopsis of the soils passed through 

 in the excavations. But these excavations are not yet completed, 

 and Mr. Horner defers all inferences as to the secular increase of the 

 alluvial deposits until he shall have had an opportunity of describing 

 the later and more extensive researches and excavations. 



Trusting that Mr. Horner may be successful in arriving at a satis- 

 factory result from this spirited and difficult undertaking, I will only 

 observe, that we must not be too sanguine that these inquiries can 

 lead to any sound or certain conclusions on the subject. The greater 

 velocity of the water in the ante-historical period, in consequence of 

 the greater inclination of the valley before it was filled up by the 

 present sediment, can never be fully ascertained, or its effects cal- 



