1865.] President's Address. 497 



PROFESSOR MILLER, 



M. Chasles being prevented from being present in person to receive the 

 Medal which has been awarded to him, I have to request you as our Foreign 

 Secretary to receive it for him, and to transmit it into his hands. It will 

 assure him of the very high estimation in which his labours, in a branch 

 of mathematical research which for more than a century has been little 

 followed and little encouraged, are held in this country. 



The Council has awarded a Royal Medal to Joseph Prestwich, Esq., 

 F.R.S., for his numerous and valuable Contributions to Geological Science, 

 and more especially for his papers published in the Philosophical Transac- 

 tions, on the general question of the Excavation of River Valleys ; and on 

 the Superficial Deposits in France and England, in which the Works of Man 

 are associated with the Remains of Extinct Animals. 



It is now not less than sixteen years since the Geological Society awarded 

 to Mr. Prestwich the "Wollaston Medal, the highest honour in their gift, 

 for the researches and discoveries he had then made ; and it may be said 

 without disparagement to the services he had then rendered to geology, 

 that the works he has since completed and published greatly outweigh in 

 amount and value what he had achieved in 1849. 



Before that time his writings comprised memoirs both on the palaeozoic 

 and tertiary strata : one on the Old Red Sandstone strata containing 

 ichthyolites, and on some beds of the glacial period at Gamrie; and 

 another, a very elaborate one, on the coal strata of Coalbrook Dale, in 

 which he explained in detail the structure of that coal-field, and the 

 arrangement and distribution of the fossils throughout a long succession 

 of the carboniferous strata. In the tertiary formations he introduced a 

 considerable reform in the classification of the English series by proving, 

 amongst other points, that the central division of the Bagshot Sands 

 coincided in date with the "calcaire grossier" of the Paris Basin, instead 

 of occupying, as was before supposed, a much higher place in the series. 



After 1849, continuing his researches on the English tertiary formations, 

 he made two other important steps in the advance of our knowledge, viz., 

 1st, by showing that the clays of the Island of Sheppey, those of Barton, 

 and those of Bracklesham, in Hampshire, instead of being all three 

 contemporaneous, according to the then received opinions, were each due to 

 a separate period, an important rectification of the chronological order of 

 the British tertiary formations ; and, 2nd, by pointing out that beneath the 

 fluviatile beds of Woolwich, or that series commonly called the plastic clay 

 and sands, there existed an older marine formation, for which he proposed 

 the name of the Thanet Sands a subdivision now generally recognized 

 and adopted. By establishing the true position of this subdivision, a 

 decided step was made towards filling up the wide gap which still divides 

 the lowest of our Eocene strata from the Maastricht beds or upper part of 

 the chalk. 



