350 ScientiJiG Intelligence. 



Tlie bibliograpliy of the (alphabetically) first elements is com- 

 plete through the year 1908 and it has been carried right up to 

 date for the last elements. Very great care has, also, been taken 

 to avoid errors in the tables of wave lengths. Consequenily, 

 volumes V and VI will be of great value to a much wider circle of 

 readers than the preceding volumes, inasmuch as the bibliographic 

 lists and the numerical tables will appeal to any investigator in 

 any subject who needs such data, whereas the first four volumes 

 deal with material which is of interest chiefly to workers in the 

 comparatively special field of spectroscopy. Judged by this 

 standard, volume V is by far the most important work on the sub- 

 ject extant. h. s. u. 



13. Physical Measurements ; by A. W. Duff and A. W 

 EwEi,L. Second edition. Pp. xi, 256. Philadelphia, 1910 (P. Blak- 

 iston's Sons & Co.). — This is the second edition of a laborat,ory 

 manual previously reviewed in this Journal (June, 1909). It 

 retains the many excellent qualities of the first edition, and has 

 been somewhat enlarged. The typography and diagrams have 

 been distinctly improved. h. a. b. 



1 4. Der Lichtbogen als Wechsehtromerzeuger y von Willy 

 Wagnee. Pp. vi,' 119. Leipzig, 1910 (S. Hirzel).— This book 

 gives a connected account of the work which has been done dur- 

 ing the last ten years upon the electrical oscillations set up when 

 an arc is shunted by capacity and inductance. The theory of 

 the phenomenon is discussed and the applications to wireless 

 telegraphj' and telephony are described. Considerable attention 

 is given to the author's own work on metallic arcs. n. a. b. 



II. Geology and Mineralogy. 



1. Diverse Effects of G lactation on the Cretaceous Clays; 

 by A. C. Hawkins. (Communicated.) — Heinrich Ries, in his 

 recent book* dealing with clay deposits, describes types of defor- 

 mation in clays, as follows : " Beds of clay and shale sometimes 

 show folds or undulations. — Many clay deposits in the Northern 

 States show a local folding caused by the shoving action of the 

 ice-sheet during the glacial period. Such folds, however, are of 

 minor account, and affect onlj' a few beds. — Where a bed is not 

 sufficiently elastic to bend under pressure, it breaks, and if, at the 

 same time, the beds on opposite sides of the break slip past each 

 other, faulting is said to occur. — Every bed terminates abruptly 

 at the fault-plane, its continuation on the other side being at a 

 higher or lower level. Displacements of this type are somewhat 

 rare in surface clays, and if occurring, the throw is not apt to 

 exceed a few feet." 



An excellent case of each of the foregoing types has been 

 brought to light by recent excavations in the Cretaceous clays of 



* Heinrich Eies : "Clays, their Occurrence, Properties, and Uses," pp. 

 28-30. 



