Notices respecting New Books. 65 



tions of the same whole, each amounting to three-fourths (or to 

 over one-half) must have a common part, — a truth so obvious that 

 few persons would think it necessary to state it, but which never- 

 theless is taught by arithmetic, not by logic." If the science of 

 Logic must hand over so simple a matter as this to Arithmetic, it 

 cannot be surprising to any one that every book on Logic devotes 

 several pages to discussing the time-honoured question of the utility 

 of what it has to offer to the reader. But Prof. Monck is perhaps 

 not aware that if he hands over the proof of this piece of reasoning 

 about the killed Prussians to the algebraist, he hands over along 

 with it the proof of every syllogistic mood. This was shown by 

 De Morgan ; but the proof has been given in a more complete form 

 in Macfarlane's ' Algebra of Logic,' where the validity of each mood 

 is proved from the principle which suffices to prove the above piece 

 of reasoning, and the necessary reductions required to bring a given 

 mood under that principle are shown to correspond to the Aristo- 

 telian process of Reduction. 



In one of his advanced chapters Prof. Monck deals very effec- 

 tively with Analytical and Synthetical judgments ; and at page 134 

 we have some remarks on the difference in function of the subject 

 and the predicate which are worthy of the attention of symbolic 

 logicians. 



Six Lectures on Physical Geography. By the Rev. S. Haughton, 

 F.R.S., M.D. Dull., D.C.L. Oxon. Dublin : Hodges, Poster, and 

 Co. London : Longmans and Co. 1880. 



Physical Geography comprises so great a variety of subjects, that 

 it is somewhat difficult to compress in a moderate compass the 

 leading facts and principles of the science. Being generally taught 

 in schools and colleges, and forming one of the subjects of science 

 examinations, many text-books have been prepared, varying in size 

 and character according to the views entertained by the different 

 authors as to the extent and bearing of Physical Geography. To 

 these may now be added the above treatise by Prof. Haughton ; 

 although recently published, it is chiefly based on a short course 

 of lectures given five years ago, the substance of which, carefully 

 revised and considerably enlarged, with numerous notes, maps, and 

 diagrams, forms the present volume. 



The first two lectures treat of the past history (including the 

 nebular hypothesis of Laplace) and future prospects of the Earth 

 as inferred from the phases which the Moon, Mars, and Venus 

 have undergone or are now passing through, — and also of the 

 origin, form, and distribution of continents, oceans, and mountain- 

 chains, as well as the phenomena exhibited by volcanos as connected 

 with the contraction of the earth's crust due to secular cooling. 



In the third lecture, besides the law of atmospheric and oceanic 

 circulation, the author treats of the scale of geological time during 

 the Azoic, Palaeozoic, and Neozoic periods, and shows, from calcu- 

 lations given (pp. 90-92), that by comparing the percentages of 

 the maximum thicknesses of the stratified rocks with the per- 



Pldl Mag. S. 5. Vol. 12. No. 72. July 1881. F 



