TEMPERATURE 



63 



7133.1. Psychrometers should be used in accordance with the following 

 instructions: 



7133.11. The wet-bulb wicking should be thoroughly moistened, taking pre- 

 caution to prevent the moisture from contacting the dry bulb. 



7133.12. Select a shady spot on the windward side of the bridge which is 

 free from spray and has no obstructions within a radius of the whirling sling. 



7133.13. Face into the wind. 



7133.14. Whirl the psychrometer as far in front of the body as conveniently 

 possible. 



7133.15. When the apparent wind is greater than nine knots, do not whirl 

 the psychrometer. The psychrometer may be properly ventilated by holding 

 the instrument in the direct wind stream and pointing the bulbs into the wind. 



7133.16. Read the wet and dry thermometers while holding the instrument 

 as far from the body as practicable. 



7133.17. Repeat the ventilating until a minimum wet-bulb temperature 

 has been reached. 



Figure 10. --Psychrometer (Portable, Aspirated, Electric). 



