146 Cambridge Philosophical Society. 



to have escaped the author's attention : in speaking of the Swiss 

 Alps, at p. 295 it is stated, that " the Oxfordian group are repre- 

 sented by the ' Neocomian ' limestones, a series of strata abounding 

 in fossils of the gault and upper greensand." According to Sir R. 

 Murchison, Von Buch, and other geologists, the occurrence of the 

 Oxfordian group with its characteristic shells is distinctly traced in 

 the French and Swiss Alps, and forms the base of all the outer edges 

 of the Savoy Alps, overlaid by the Neocomian limestones, which are 

 again surmounted in the Savoy Alps by a dark-coloured limestone, 

 which, from its contained fossils, fairly represents the gault and 

 upper greensand. 



The concluding part of the work is devoted to general principles, 

 in which we find the theories of organic life discussed, especially as 

 bearing on the development hypothesis, — the causes of extinction 

 of the various forms of animated life which have successively tenanted 

 our globe, — the analogical order of moral and physical progression, 

 — as well as a chapter on the Mosaic account of creation as recon- 

 cilable with geological discoveries ; want of space prevents us from 

 extracting the many valuable and eloquent passages contained in 

 this portion, involving points of the highest interest. 



To those who have not hitherto investigated the varied and mul- 

 tiform changes, both organic and inorganic, to which the superficial 

 crust of our globe has been subjected, or have regarded geology as 

 an unprofitable and uninviting study, and to the geologist himself 

 occupied merely with the laborious task of collecting the dry statical 

 details connected with his science, we cordially recommend the per- 

 usal of this volume, as unfolding in the plainest manner the beauty, 

 harmony and beneficence of Creative power that has reigned through- 

 out all past time, and by which the present surface of our earth has 

 been elaborated, modified, and adapted to the wants of an intellectual 

 and moral being, pointing out to us at the same time, that as an 

 inquiry " into the records of Creation, geology has disclosed views, 

 and elicited discoveries, of the works of the Divine Architect of the 

 world which the religious inquirer will as cordially embrace, as ig- 

 norance can overlook or misapprehend." 



XVI. Proceedings of Learned Societies. 



CAMRRIDGE PHILOSOPHICAL SOCIETY. 



[Continued from p. 69.] 

 Feb. 25, /^|N the Symbols of Logic, the theory of the Syllogism, 

 1850. ^-? and in particular of the Copula, and the application 

 of the Theory of Probabilities to some questions of evidence. By 

 Professor De Morgan. 



This paper, which is in continuation of the one published in 

 vol. viii. part 3 (read Nov. 9, 1846), and of subsequent additions 

 contained in the author's work on Formal Logic, is divided into six 

 sections. 



Section I. On the approximation of logical and algebraical modes 

 of thought. — The subjects of this section are, — 1st, some development 

 of the idea that the oppositions of logic have affinities which may 



