Reviews — TealVs * Sedgwich Prize Essay." 41 



reference in regard to this we find in the 32nd chapter, which details 

 the observations and calculations of Dr. Edmund Andrews, President 

 of the Chicago Academy of Science. In a remarkable paper on the 

 North American Lakes, Dr. Andrews shows good cause for believing 

 that their present outlines are post-glacial, and that " the total time 

 of all the deposits (since the Glacial Period) appears to be some- 

 where between 5300 and 7000 years ; and further, that the country 

 has undergone changes of level since the Glacial Period." Dr. 

 Andrews and Mr. Belt are at opposite poles. 



We cannot fail to perceive that geologists are reducing their 

 figures. We no longer hear of millions of years. The acute re- 

 viewer of the present book in the Spectator of November 27th, 

 proposes20,000 years as the duration of man on the earth. But in 

 truth all positive statements of this kind are open to the same 

 objections as are the smaller figures. We are not yet in a condition 

 to measure the units, though we have advanced so far as to be able 

 to say that the entire quantity need not be so long as was at one time 

 conceived to be required by the evidence. 



Every one who has watched the course of a long legal trial is 

 well acquainted with the swaying to and fro of opinion during its 

 pendency. We are still in this oscillating stage. Mr. Southall ably 

 sums up as an advocate for recency. We shall have further evidence 

 and a reply, and then, at some unknown future period, a competent 

 judge will intervene and put the whole case impartially before the 

 jury of public scientific opinion, and a true verdict will doubtless be 

 given. Meanwhile we wait in the " Salle de pas perdiies." — S. K. P. 



III. — The Potton and Wicken Phosphatio Deposits. Being the 

 Sedgwick Prize Essay fok 1873. By J. J. H. Teall, B.A., 

 F.G.S. (Cambridge, Deighton, Bell & Co. ; London, George 

 Bell & Sons, 1875.) 



THE Sedgwick Prize is given every third year for the best Essay 

 on some subject in Geology, but the competition is limited to the 

 Graduates of the University of Cambridge loho have resided luithin one 

 mile and a half from the University Church for sixty days during the 

 twelve months preceding the day on or before which the Essay must be 

 sent in. This is the first time that the Prize has been awarded, as no 

 essay was sent in for the years 1867 and 1870. 



The subject proposed was "The Potton and Wicken Phosphatio 

 Deposits, and their general relation to the Necomian Strata of Western 

 Europe, lying between the Portland Beds and the Gault." The 

 publication of this Essay has been delayed to make the work more 

 complete. The author in the first chapter gives a somewhat im- 

 perfect account of the "literature of the subject," which we need 

 not notice, as most of the readers of this Magazine are quite 

 familiar with these deposits. He next gives an account of the 

 Potton deposit. The chief new points are a careful description 

 of the pebbles, and an attempt to determine the species of the 

 derived moUusca ; the author also shows that an older Neoco- 



