ANNIVERSARY ADDRESS OP THE PRESIDENT. XXXVII 



Eoyal Society, which resulted iu limiting to fifteen the number of 

 new Members to be annually elected, and in introducing very 

 important changes in the mode of election. He was also for 

 some time engaged in publishing and editing the memoirs of his 

 brother, Francis Horner. 



In April 1850 Mr. Horner communicated to this Society a 

 notice of some observations of Prof. Lepsius respecting the change 

 of level of the water of the Nile during the last 4000 years, from 

 which it appeared that the bed of the river had been lowered 

 about 28 feet during that period. Mr. Horner could not agree 

 with these conclusions, and it is probable that the difficulty of 

 explaining the phenomena described by Prof. Lepsius induced 

 him to undertake those investigations respecting the levels of the 

 Nile, which he afterwards carried out. 



In May 1854 he read a paper on some intrusive igneous rocks 

 in Cawsand Bay, near Plymouth. After describing the conditions 

 in which these porphyritic rocks occur amidst the argillaceous 

 schistose rocks and hard arenaceous red sandstones and conglo- 

 merates, he concludes with some suggestions as to the theory of 

 this association of igneous and sedimentary rocks, and thinks it 

 probable that the igneous rock was poured into a vast irregular 

 cavity, parallel to the plane of stratification, during a submarine 

 outburst. 



In the volume of the Philosophical Transactions for 1855, he 

 ptiblished an account of the recent researches near Cairo, which 

 he had caused to be undertaken with the view of throwing light 

 upon the geological history of the alluvial land of Egypt. The 

 method adopted by Mr. Horner in this investigation was to com- 

 pare the depth of sediment which had accumulated, to a consider- 

 able height, above the base of the oldest works of art near the Nile, 

 with that of 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 

 between earlier and later periods.* 



Shortly after this Mr. Horner resigned the Inspectorship of 

 Pactories, and from that time his attention was more particularly, 

 I might say exclusively, devoted to the interests of this Society. 

 The question of the arrangement of the contents of our Museum 

 had been seriously taken up by the Council, and a Committee, of 

 which Mr. Horner was the Chairman, had been appointed for the 

 purpose of carrying out their views. It is not too much to say 

 that of this Committee he was the most active Member. Very 

 elaborate catalogues of the fossils of the different formations, both 

 in the British and Poreigu Collections, were prepared by Mr. 



* Quart. Journ. Geol. Soc. vol. xii. President's Address, p. xcix. 



