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POPULAR SCIENCE MONTHLY. 



head of this river, by Monctin twenty miles 

 from the bay head, the bore is seen to best 

 advantage ; it rushes in ' as a foaming break- 

 er, five or six feet high, with a velocity of five 

 or six miles an hour.' The spring and neap 

 tides have forty-five and thirty-eight feet 

 range. The ebb tide runs like a mill race ; 

 the water rapidly sinking, and the river is 

 reduced to a small meandering stream. It 

 so remains about two hours, when the rush- 

 ing waters of the bore are heard again, and 

 the river is soon filled with their sweeping 

 flood." 



Necessities of Geoiogical Time. One of 



the questions considered by Prof. E. B. Poul- 

 ton, in his presidential address before the 

 Geological Section of the British Associa- 

 tion, related to the length of time required 

 for the development of animal life on the 

 earth to its present condition " whether the 

 present state of paleontological and zoological 

 knowledge increases or diminishes the weight 

 of the opinion of Dartvin, Huxley, and 'Spen- 

 cer, that the time during which the geolo- 

 gists concluded that the fossiliferous rocks 

 had been formed was utterly insufficient for 

 organic evolution." The arguments of the 

 physicists, derived from the supposed effect 

 of tidal action upon the length of the day, 

 and from the estimated length of the time 

 occupied by the earth in cooling from an 

 assumed temperature to its present condition, 

 are shown to have been proved invalid as 

 bases for calculatmg the probable age of the 

 earth as a life-bearing body. The argument 

 derived from the supposed life of the sun 

 has not yet been ruled out, and that gives a 

 maximum of five hundred million years. 

 The computation of the time required for 

 depositing the geological strata gives a mini- 

 mum of seventy-three million and a maximum 

 of six hundred and eighty million years 

 possibly four hundred million years. The 

 author's inquiry as to how much of the 

 whole scheme of organic evolution has been 

 worked out in the time during which the fos- 

 siliferous rocks were formed does not deal 

 with the time required for the origin of life 

 or for the development of the lowest beings 

 with which we are acquainted from the first 

 formed beings, of which we know nothing ; 

 but only with so much of the process of 

 evolution as we can infer from the structure 



of living and fossil forms. The comparison 

 is made from a study of the evolution of the 

 phyla. All available evidence points to the 

 extreme slowness of progressive evolutionary 

 changes in the cojlenterate phyla, although 

 the protozoa are even more conservative. 

 When we consider further on the five ccelen- 

 terate phyla that occur fossil, we shall find 

 that the progressive changes were slower, 

 and indeed hardly appreciable in the echi- 

 .noderms and gephyrea, as compared with 

 the mollusca, appendiculata, and vertebrata. 

 Within these latter phyla we have evidence 

 for the evolution of higher groups, present- 

 ing a more or less marked advance in organi- 

 zation. As a whole, the comparison is quite 

 enough to necessitate a very large increase 

 in the time estimated by the geologist. We 

 can hardly escape the conclusion that, for 

 the development of the arthropod branches 

 from a common chetopodlike ancestor and 

 for the further development of the classes 

 of each branch, a period many times the 

 length of the fossiliferous series is required. 

 The evolution of the ancestor of each of the 

 higher animal phyla probably occupied as 

 long a period as that required for the evolu- 

 tion which subsequently occurred within the 

 phylum. But the consideration of the higher 

 phyla which occur fossil, except the verte- 

 brata, leads to the irresistible conclusion that 

 the whole period in which the fossiliferous 

 rocks were laid down must be multiplied 

 several times for this later history alone. 

 The period thus obtained requires to be again 

 increased and perhaps doubled for the ear- 

 lier history. 



The New Zealand Alps. The " Alps " of 

 the Southern Island of New Zealand are de- 

 scribed by Mr. Fitz-Gerald as being more like 

 the Pyrenees than the Swiss Alps in struc- 

 ture, in that they are a single range rather 

 than constituted of parallel folds. The high- 

 est peak, Aorangi, or Mount Cook, is 12,349 

 feet high, but not many of the others rise 

 above 10,000 feet. The snow line is, how- 

 ever, 2,000 feet lower than in Switzerland, 

 and the glaciers descend much neaier to the 

 sea level, the great Tasman Glacier coming 

 down to about 2,350 feet, several to 1,200 

 feet, and the Fox Glacier to 700 feat. Nearly 

 twice as much snow falls upon some of their 

 slopes as at corresponding positions on the 



