482 Scientific Intelligence. 



tance, <? (100) , between the lattice planes is derived from the obvi- 

 ous relation : — (mass of 1 copper atom) = (volume) (density) = 

 Wioo)) 3 • 8 '96 = (atomic weight of copper) (mass of 1 hydrogen 

 atom) = 63-57 . 1'64 . 10 -2 * gram, therefore d {m) = 2*26 X 10 _8 cm. 

 For an anticathode of palladium, such as was used in the experi- 

 ments, A. = 0*576 . 10~ 8 cm. IJence, substitution of the values 

 for d( m ) and X in the well-established equation A. = 2e? (100) sin 6 

 gives (1OO) = 7° 20'. In like manner, (UO) = 10° 22' and (111) = 

 12° 50'. These angles were not found experimentally when the 

 crystals were studied by means of an ionization X-ray spec- 

 trometer. On the assumption that the copper crystals have one 

 atom at the center of each cube face in addition to the atoms at 

 the vertices of the cubes the above method of calculation leads to 

 the following glancing angles, namely : — (1OO) =9° 13', (no) =13° 2', 

 and (lu) = 8° o'. The angles actually obtained by reflection were 

 9° 24', 13° 18', and 8° 0' respectively. The experimental check 

 used to avoid ambiguity of solution need not be discussed in this 

 place. Bragg says "... there can be little doubt that the 

 atoms of a copper crystal are arranged on a face- centred cubic 

 lattice". "The crystal structure is the most simple of any as yet 

 analysed." — Phil. Mag., xxviii, p. 355, Sept., 1914. h. s. u. 



II. Geology and Mineralogy. 



1. The Deseado Formation of Patagonia ; by Frederic B. 

 Loomis. Pp. i-xi, 1-232, with frontispiece and 160 text figures. 

 Amherst, published under the auspices of the Trustees of Amherst 

 College, 1914. — This volume is the technical conclusion of a pre- 

 vious work, " Hunting Extinct Animals in the Patagonian Pam- 

 pas," published by Dodd, Mead and Company in 1913, and 

 together the two sum up the exploration and anatomical work 

 done by the Eighth Amherst Expedition, which, under the leader- 

 ship of Professor Loomis, explored a little known portion of 

 Patagonia in 1911. 



The material described in the volume under consideration 

 forms a unified body of data which adds much to our knowledge 

 of the animals of the Patagonian Tertiary. The field, however, 

 has only been touched and a vast amount of further work can be 

 profitably done on the horizons immediately preceding and fol- 

 lowing the one described in this volume, after which an interest- 

 ing study can be made on the evolution of a fauna which 

 developed in a considerable degree of isolation. 



Material was found in various beds, from the Cretaceous up to 

 the Lower Miocene ; but the major part of the fossils and most 

 of the facts new to science came from the Deseado formation, 

 otherwise known as the Pyrotherium beds and attributed by 

 geologists to the Upper Oligocene period. Chapters I and II 

 discuss the localities and age of the formation in Patagonia, 



