132 Revieivs — Geological Survey of England. 



popular, and a tliird edition was published in 1854. In bringing 

 out the present edition Mr. Tate tells us that it Las been found 

 necessary to re-write the work, and he has divided it into two parts, 

 the one entitled "Historical Geology," a new and independent trea- 

 tise ; the other, which is now before us, entitled " Physical Geology," 

 containing some portion of the letter-press and many of the illustra- 

 tions of Portlock's work. Comparing this with our old volume of 

 Portlock, the third edition, we find that great improvements have 

 been made by additions and alterations, necessitated by the progress 

 of geology, but there nevertheless remains so much of the original 

 work that we are at a loss to understand why Mr. Tate did not in 

 this volume adopt the more modest title of Editor rather than that of 

 Author. We do not find fault with the book, but we think that 

 sufficient justice has hardly been done to Major-General Portlock. 

 Mr. Tate has made many additions to the physical part, while that 

 section which relates to palaeontology, the fossilization of plants and 

 animalsj and their geographical distribution, has received important 

 modifications. We can recommend it as a useful introduction to 

 the more advanced Manuals of Jukes and Geikie or Dana. For, as 

 Jukes remarked many years ago, in the preface to his " Popular 

 Physical Geology," there can hardly be too many elementary books 

 which are the results, more or less completely, of actual experience, 

 and not the mere compilation and compression of other books. Not 

 because any of them would contain a large amount of matter not to 

 be found in all the rest, but because, by the different order and 

 arrangement of the different writers, the matter may be looked at on 

 all sides and in every light. Thus we are glad to see this new 

 edition of Portlock's useful little Treatise on Geology. 



III. — Geological Suevey of England. 



WE are happy to announce the publication of the new 

 edition of Sheet 7 of the Geological Survey Map of 

 England, showing all the Drift deposits, on the scale of one 

 inch to a mile. For some time past we have been looking for- 

 ward to the completion of this map, and we must now congratu- 

 late the Survey on this first issue of the Drift maps. A glance at 

 the old edition, comparing it with this new one, shows at once the 

 great utility of mapping all the superficial deposits, for not only 

 have they a high economic value, but in their relations to drain- 

 age and health, an inquiry which we are glad to observe is attracting 

 public attention, their importance cannot be over-estimated. 



The area comprised in this sheet, about 800 square miles, includes 

 the western part of London. It is bounded on the east by Hornsey 

 and Enfield ; on the north it takes in Hatfield Park, St. Albans, 

 Hemel Hempstead, Great Berkhampstead, and Wendover ; on the 

 west it extends beyond Princes Risborough, Great Marlow, and 

 Twyford in Berkshire ; while to the south it includes Windsor and 

 the Great Park, Staines, Twickenham, Wimbledon Park, and 

 Dulwich. 



