70 Scientific Intelligence. 



the reader is thus carried through from one chapter to the next 

 with unflagging interest. Developed from a series of lectures 

 delivered in Washington, in 1891, the author has retained the 

 lecture room form, which brings him at once into close contact 

 with his larger audience and makes them feel and share his inter- 

 est and enthusiasm. The book is fresh in matter throughout, 

 and while not aiming at originality, it gives with fullness the 

 results particularly of recent investigations in this department ; 

 as, for example, the well-known work of Koenig on beats and 

 beat-tones produced by the simple notes of tuning forks, also the 

 proof of the influence of difference of phase upon the quality of a 

 compound musical note. It is a book which every practical 

 musician can read and study with much profit, and which may 

 be used advantageously by students who are approaching the 

 subject of acoustics from a more theoretical side. 



II. Geology and Mineralogy. 



1. View of the Ice Age as One Glacial Epoch. — Mr. Upham 

 closes an important paper on the "Accumulation of Drumlins" in 

 the American Naturalist for December, with the following para- 

 graphs. : 



"In conclusion, I deem it a duty to state that this reference of 

 the drumlins, terminal moraines, kames, and eskers, to rapid ac- 

 cumulation from previously englacial drift during the departure 

 of the ice, seems to me better accordant with the view that the 

 Ice age comprised only one great epoch of glaciation, attended by 

 oscillations of the ice-border, than with the alternative view which 

 supposes the ice-sheets to have been at least once and perhaps 

 several times almost entirely melted away, afterward being 

 restored by recurrent glacial epochs. This belief in the unity of 

 our glaciation I held during my work on the New Hampshire 

 Geological Survey in the years 1874 to 1878; but in my ensuing 

 work on the survey of Minnesota, the peat and forest beds 

 enclosed between deposits of till in that region led me to accept the 

 duality or plurality of glacial epochs as taught by Croll, James 

 Geikie, N. H. Winchell, Chamberlin, Shaler, McGee, Salisbury, 

 and at present by most American glacialists. The recent state- 

 ment by Prof. G. F. Wright of the evidence for the unity of 

 Quaternary glaciation as the more probable view,* expresses a 

 similar opinion with that to which I have been gradually return- 

 ing, during the past year or longer, through the guidance of my 

 investigations in this field. Moraines and drumlins are effects of 

 secular vicissitudes of climate on the border ol the departing ice- 

 sheet. The ice sheet, I think, owed its existence to great altitude 

 of the land at the beginning of the Glacial period, to have been 

 attended when at its maximum extension and volume bj T depres- 



* "Unity of the Glacial Epoch," this Journal, III, vol. xliv, pp. 351-373, Nov., 

 1892. 



