33 



ana- 



Mr HOPKINS, ON RESEARCHES IN PHYSICAL GEOLOGY, 

 previous Article will no longer be accurately true; but since the v 

 tion of p as a function of y will be very slow, I may still, for a first 

 approximation, be considered constant from y = o to y = a considerable 

 value. Consequently both the equations (1) and (2) of Art. 25 mav in 

 our present case be considered as approximately true. 



27. The case at which we have last arrived is exactlv similar u 

 ABGH of the lamina, bounded by a line HMG. similar to EQF, 



may be considered as being retained in its actual position, by the ten 

 szons actmg parallel to AU and BK at every point of ^G, exactly in' 



enter' TT " '^"' '" ""^"'^ "^ ^""^ ^"PP-^'i ^^e lamina repre- 

 sented m the figure m p. 31, to be kept in its position by forces act^nc' 

 at each poxnt of HG in that figure. Also it has been shewn (Irt 2" ) 

 that the curvature of any such line as IJQF, varies very slowly with 

 Its distance from AB. Consequently the variation of „ the radius of 

 curvature at Q, is extremely small, considered as a function y (AE) 

 This bemg the case, it is manifest likewise (assuming the original system 

 of tensions parallel to AB, to have been uniform)* that T (the tensio"! 

 of EF) will vary very slowly with AE ; and that therefore 1' as a 



function of y, may approximately be considered constant. Consequently 

 we shall navp in fViic ^r.^^ ^ ■' 



^' = — . y, nearly. 



Vol. VI. 



• This .8 not essential to the truth of our general conclusions. 

 Paet I. E 



