84 Scientific Intelligence. 



by the Coast and Geodetic Survey in their triangulation work 

 have been changed in position. . . . 



"The great length of the rift upon which movement has occurred 

 makes this earthquake unique. Such length implies great depth 

 of rupture, and the study of the question of depth will, it is 

 believed, contribute much to current geophysical conceptions. 



" The time of the beginning of the earthquake as recorded in 

 the Observatory at Berkeley was 5 h. 12' 6" a. m., Pacific stand- 

 ard time. The end of the shock was 5 h. 13' 11" a. m., the dura- 

 tion being 1' 5". Within an hour of the main shock twelve 

 minor shocks were observed by Mr. S. Albrecht of the Observa- 

 tory and their time accurately noted. Before 6 h. 52' p. m. of 

 the same clay thirty-one shocks were noted in addition to the 

 mam disturbance. These minor shocks continued for many days 

 after April. 18, and in this respect the earthquake accords in 

 behavior with other notable earthquakes in the past. The minor 

 shocks which succeed the main one are interpreted generally as 

 due to subordinate adjustments of the earth's crust in the ten- 

 dency to reach equilibrium after the chief movement." 



The destructive effects of the earthquake are in the main dis- 

 tributed with reference to the line of rift, and are evident over 

 an area approximately 50 by 400 miles. Within this area the 

 intensity of the shocks varied greatly in accordance with topo- 

 graphic position and the character of the underlying rocks. The 

 facts indicate an "excessively destructive effect of the earth 

 wave as transmitted by the little coherent formations of the 

 valleys bottoms." 



A discussion of the geological problems presented by the 

 earthquake is left for a more exhaustive report. 



2. United States Geological Survey, Charles D. Walcott, 

 Director. — The titles of publications recently received are given 

 in the following list (see vol. xxi, 251, March, 1896): notices of 

 some of these follow later. 



Third Annual Report of the Reclamation Service. 1903-4. 

 (Second Edition.) F. H. Newell, Chief Engineer. Pp. 653, 

 with 59 plates in separate cover. — The Act of Congress, looking 

 forward to the reclamation of the arid lands in the Western 

 States and Territories, was passed in June, 1902. Since then 

 three reports of the Reclamation Service connected with the Sur- 

 vey have been published; the last of which, in revised form, has 

 recently been given to the public. It gives a summary of the 

 various extensive operations planned, and shows that when they 

 are brought to completion the results will be of the highest 

 importance, not only for the regions involved, but for the country 

 at large. 



Topographic Atlas. — Twenty-seven sheets. 



Folios: No. 130. Rico Folio : Colorado. Description of the 

 Rico Quadrangle ; by Whitman Cross and F. L. Ransome : 

 Geography and General Geology of the Quadrangle by Whit- 

 man' Cross. Pp. 20, with 5 colored maps and 6 figures. 



