PHYSICS: E. H. HALL 
297 
Fort Oglethorpe. Up to April 27, 1918, when new methods were put into 
use, approximately 140,000 soldiers had been examined. On July 1, 1918, 
600,000 had been examined. Of this number, slightly more than 0.25% 
had been recommended by psychological examiners to psychiatrists for dis- 
charge because of mental deficiency, and about 0.5% had been recommended 
for assignment to service organizations for development battalions because 
of mental inferiority. 
Psychological examinations which were originally conducted in wards of 
Base Hospitals, are now made in a psychology building located usually in the 
Depot Brigade. In this building, drafted men are examined promptly on 
reporting to camp. Their intelligence ratings are immediately transmitted 
to the Personnel Officer of the camp. All cases of mental deficiency, or those 
for which psychiatric examination is indicated as desirable, are referred to 
the psychiatrist. 
The aim of the Division of Psychology, Surgeon General's Office, is to develop 
a psychological center in each military training camp to which all psycho- 
logical problems of military assignment, training, discipline, morale, and in- 
telligence may be referred by officers of the line or staff. Such a center exists 
in twenty-five camps, and the service is being extended as rapidly as available 
personnel permits. 
(Publication approved by the Board of Publications, Office of the Surgeon 
General.) 
THERMO-ELECTRIC ACTION WITH THERMAL EFFUSION IN 
The last paragraph of my paper in these Proceedings for April, 1918, 
dealt incorrecly with the effect of 'hypothesis (B)' the hypothesis that free 
electrons in the interatomic spaces of an unequally heated metal bar have a 
tendency like that which in ordinary gases produces the phenomena of ther- 
mal effusion. 
In a common gas the condition of equilibrium maintained by thermal 
effusion is not p constant but p oc T% where T is the absolute temperature. 
In dealing with the free electrons, for wjiich the R of the equation pv = 
N RT may not be a constant, we have as the condition which thermal effusion 
tends to create 
METALS: A CORRECTION 
By Edwin H. Hall 
Jefferson Physical Laboratory, Harvard University 
Communicated August 3, 1918 
p* (RT)* 
(1) 
whence 
(2) 
