OF THE NATIONAL RESEARCH COUNCIL 143 



In addition to noting the effects of the mask on various 

 forms of reaction, Dodge made special study of head air space, 

 characteristics of eye pieces, ventilation of the face, adapta- 

 tion and tolerance, recovery of capacity after removal of the 

 mask, side Inspirational tubes, the relation between neuro- 

 muscular depression and the ability to endure the mask, 

 regulation of the pressure of the head-gear, gas mask sizes, 

 the most economical development of tolerance to gas mask 

 tenancy of long duration, the relative military value of differ- 

 ent mask types for long tenancy, and the effects of resistance 

 on tenancy and the performance of military tasks. 



Major Knight Dunlap was assigned to duty with the 

 Chemical Warfare Service to continue and extend the investi- 

 gations on tenancy of the gas mask initiated by Dodge. His 

 attention was confined in the main to measurement of the 

 visual fields of different types of gas masks by an original 

 method which dispensed with the head-gears and also to the 

 development of a pneumatic scheme for measuring relative 

 pressures on the head at different parts of the mask. This 

 scheme, perfected technically by the Goodrich Company, was 

 subsequently applied to the comparison of different types of 



mask. It served to show that the mask, even when 



so adapted as to be leak proof, exerted less pressure, and also 

 showed a more even distribution of pressure, than the other 

 masks previously used, although the latter were not free from 

 leaks even with the higher pressures employed. 



Just prior to the signing of the armistice, Dunlap had 

 perfected a procedure for determining the effects of different 

 types of masks on the efficiency of the wearer. He proposes 

 to continue this inquiry In his own laboratory in view of the 

 practical value of a perfected mask in certain civilian occu- 

 pations. 



The Chemical Warfare Service further sought the ser- 

 vices of the Psychology Committee In connection with the 

 problem of camouflaging odors, and as a result of a conference 

 with Captain Carleton, Vice-chairman Baird of the Psychol- 

 ogy Committee prepared a report In which he summarized 

 pertinent physiological and psychological literature on the 



