December 15, 1922] 



SCIENCE 



687 



during one or more comparatively early stages 

 of the Pleistocene ice from the north advanced 

 over the Colnmbia Plateau in a southwesterly 

 direction far beyond what heretofore has been 

 regarded as the southern limit of glaciation. 

 The evidence at hand tends to show that the ice 

 extended at least over large parts of Spokane, 

 Lincoln and Adams counties, and less complete 

 information suggests the possibility that the 

 glaciation extended much farther. 



Concerning the glacial drift, which by the 

 way is not the only evidence the region affords 

 that land dee was formerly present, the alterna- 

 tive ideas that it was brought to place by float- 

 ing ice or running water have been considered 

 and rejected. Large patches of the drift may 

 be seen southwest of Cheney, west of Lantz, 

 and in the neighborhoods of Winona, Lacrosse 

 and Kahlotus, these occurrences being selected 

 for mention at random and not because they 

 are more typical than scores of others scattered 

 throughout the region. 



The writer wishes to point out that he does 

 not herein attempt to correlate or otherwise 

 define the relations between the glaciatdon de- 

 scribed and the glaciation already known to 

 have covered the plateau west of the Grand 

 Coulee or an ice stream which, as shown by 

 recent observations, traversed the coulee itself. 

 J. T. Pardee 



U. S. Geological Survey 



EFFECTS OF COPPER WIRE ON TREES 



In 1918 the writer heard it stated that shade 

 trees were being killed by driving one or two 

 pieces of copper wire into each. To test the 

 effects of copper wire six young trees from two 

 to four inches in diameter were selected, and 

 on March 21, 1919, there were driven into each 

 tree five pieces of large copper wire 1.5 inches 

 long. The end of each wire was left flush with 

 the outer surface of bark. All wires were with- 

 in six feet of the base of the tree. The trees 

 comprised two hemlocks, two alders, one cedar, 

 one willow. 



On July 3, 1922 the trees were examined and 

 found to be perfectly healthy. In all cases 

 they had completely healed over the wires, and 

 their growth was equal to that of other similar 



trees in the immediate vicinity. On cutting 

 into the trees, it was found that there was very 

 little injury to the wood, merely a brown color 

 showing for about 1.5 inches above and below 

 the wire, and about 0.25 inch to each side. 



George B. Eigg 

 University of Washington 



TANGENT LINES 



Osgood and Graustein state in their Analytic 

 Geometry, page 176 : "A tangent to a conic 

 might then be defined as the limiting position 

 of a line having two points of intersection with 

 the conic, when these points approach coin- 

 cidence in a single point." This accords with 

 the ancient idea of a tangent as touching a 

 conic at only one point. That idea is given in 

 a paragraph on page 163 of my History of 

 Mathematics, from which Professor G. A. Mil- 

 ler quotes^ part of a sentence and then criti- 

 cizes that part. I illustrate this mode of criti- 

 cizing by quoting from Professor Miller's re- 

 view the following: "Students can usually 

 prove a large number of theorems which they 

 do not understand." Serious-minded readere 

 would deny this statement, but when they read 

 the whole sentence and the paragraph from 

 which this fragment is taken, they will ac- 

 quiesce. 



Florian Cajori 



SCIENTIFIC BOOKS 



A Treatise on the Analysis of Spectra. By 

 W. M. Hicks, ScJ)., F.R.S., emeritus pro- 

 fessor of physics in the University of Shef- 

 field, formerly fellow of St. John's College, 

 Cambridge. Cambridge Univei-sity Press, 

 1922, 231 pp. of text, 92 pp. of tables and 

 25 figures. 



The purpose of the book is twofold, to serve 

 as an introduction and handbook and to pre- 

 sent the mature results of the author's extensive 

 investigations. The treatise is based on an 

 Adams prize essay presented in 1921. For the 

 first pui'pose the appendix contains the 

 Meggers and Petei-s tables for corrections to 

 be added to the wave-lengths in air to reduce 



1 This Journal, October 13, page 421. 



