284 REVIEWS 



Vol. XXXIII of the Transactions of the American Institute, 1903, and 

 another by Professor A. P. Coleman, in the Annual Report oj the Bureau 

 of Mines of Ontario, 1903. Dr. Barlow is in essential accord with Pro- 

 fessor Coleman, though differing in details and emphasis on certain points. 

 He differs from Mr. Dickson in putting emphasis on the magmatic segre- 

 gation of the ore rather than on the secondary concentration. Dickson 

 concludes that the preliminary concentration accompanying the intrusion 

 of the norite was comparatively slight ; that appeal must be made to a more 

 distant source of the metals, probably minutely disseminated in the rocks 

 through which the depositing solutions passed; and that, in general, the 

 whole weight of the evidence points to the secondary formation of the 

 Sudbury ore-bodies as replacements along crushed and faulted zones, 

 with only minor indications of open cavities. 



C. K. L. 



