Shearer: de Morgan 5c FiLchs. 



tiyjii.f,^ 



lUfg...: .'"^ - 



&=:. 



-:> 



vll#,'^^ 





Mi/; 



H.MFdcl 



Phil lycuis. B.vot 304. PL. ^3 



UnivatniVy Press.Cambrldae 



