406 Scientific Intelligence. 
\ 
12. Elementary Lessons on Sound ; by Dr. W. H. Stone. 191 
pp. 12mo. London, 1879. (Macmillan & Co.).—The fundamental 
principles of Acoustics are fully and clearly stated and illustrated 
with numerous figures and practical examples. 
author passes to the development of the theory of music, and 
explains it, so far as space permits, in a very clear and satisfactory 
manner. He makes use of the results of the more recent investi- 
gations in this field, and thus puts within the reach of the student 
much that would otherwise be inaccessible to him. 
Il. GEoLoagy AND MINERALOGY. 
1. On some points connected with the igneous eruptions along 
the Cascade Mountains of Oregon ; by Tuomas Conpon. 
(From a letter to J. D. Dana, dated Eugene City, Oregon, July 
1, 1879.)—[The letter was written in reply to an inquiry respect- 
ing the continuity of the lavas of Mt. Hood and the Cascade 
Region with those of Mt. Adams and Mt. St. Helens, and relating 
to other points bearing on the extent of the eruptions southward 
along the Cascade range.—z. D. D. : 
The Cascade range trom Klamath River, south of the Columbia, 
to Mt. Rainier, on the north, has somewhat of the outline of a pr 
trate tree, far gone to decay. The main trunk is well represented 
by the main range; and at almost regular intervals along the whole 
line, we find, lying by its side, the remnants of its former limbs; 
not entire limbs now, but the knots that survive to represent them. 
Beginning at the north we find in the Simcoe Mountains, directly 
east of Mt. Adams, an evident outflow of eruptive material from 
that center; tilted and broken, yet in line. Twenty-five or thirty 
miles south of Simcoe Mountain, we find another such in the 
n 
Klikitat Mountain; at the foot ot which flows the Columbia 
5 
fers 
eee 
at 
ioe 
ert 
Shee i tesla aaa 
