238 BELL SYSTEM TECHNICAL JOURNAL 



While the mechanism of the direct reading recorder is more com- 

 plicated than that of the difference recorder, it is a more useful instru- 

 ment, both because the humidities may be read directly, thus saving 

 the labor of interpretation of the records, and because the records are 

 more significant. The direct reading recorder, furthermore, may 

 be used to control the functioning of air conditioning apparatus at 

 any desired conditions, at the same time that it is actually recording 

 these conditions. Accordingly, it should prove particularly useful 

 in maintaining proper humidity in apparatus and operating rooms. 



