Geological Society. 



571 



In a similar manner can be shown that (22) holds for odd 

 values of k. 



It follows from (21) that A, is formed in the same way as 



Qt+\?i-i-2t (if it existed). 

 Hence 



L"-^] 



L — 2 — J /ft + f-ix"- 1 " 2 '-^ 



/ -+/8+t _i\ 



i 



-2^-26- a-l 



and 



D^l 



B,= 2 (-lyi'f,'.! 2 (-l)V 



j3 = ^ ' a=0 



w /a4/3 + £-l\ 



X( £ + £_! )™n-2t-2?- 



\~n-2-2tl 



L 2 J , R > t \n-2-2t-2fl 



b 2 f-iyiAPj 1 ) X (-l) c 



/3=0 \ l I <x=0 





(29) 



2-2«-2/3-a? 



A/^j + B^ being the numerator of the fraction whose 

 denominator is (x 2 +aoc- ) rby~ t . 



University of Pennsylvania, 

 Philadelphia, Pa. ? U.S.A. 



LXVIII. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



[Continued from p. 496.] 



February 23rd, 1916.— Dr. Alfred Harker, F.E.S., President, 

 in the Chair. 



rpHE following communication was read : — 



'On the Origin of some River-Gorges in Cornwall and Devon.' 

 By Henry Dewey. F.G-.S. 



In North Cornwall, near Tintagel, there is an area of peculiar 

 topography characterized by the presence of an upland plain or 



