Of a New Hygrometer. 107 



Experiment 4.-9 A.M. Instruments as in the first ex- 

 periment. 



Temperature of the air 68°. 



Ditto of moistened bulb 61°. difference T x 6=42°. 



Leslie's Hygrometer 42°. 



Mason's Ditto . 42°, no difference indicated. 



Experiments. — Half-past 9 A. M. Window shutters open. 

 Sun's direct rays not upon the instruments ; but much re- 

 flected light from different parts of the room. 



Temperature of air . 72°. 



Ditto of moistened bulb 65°, difference 7° x 6=42°. 



Leslie's Hygrometer 50°. 



Mason's Hygrometer 42°— =8°+ Leslie's. 



A variation of 8 degrees for reflected lighC. 



Experiment 6.— 10 A.M., Instruments in the shade ; 

 doors and windows open ; strong current of air upon the 

 Hygrometers. 



Temperature of air 71°. 



Temperature of moistened bulb 63° difference 8°— 

 0-666. Correction for current of air=7°-334 x 6=44°-094. 



Leslie's Hygrometer 58°-000. 



Mason's Hygrometer 44°-004~- = 13°-996 + Leslie's. 



Giving a false indication of 13°-996 degrees for current 

 of air. 



Experiment 7.— Noon : instruments as in the first expe- 

 riment. 



Temperature of air . . . . 70°. 



Temperature of moistened bulb 62° difference 8° x 6=48°, 



Leslie's Hygrometer 48°. 



Mason's Hygrometer 48°, no difference indicated. 



Experiment 8. — 1 P.M., Window shutters open; the 

 direct rays of the sun fall upon both instruments. 



Temperature of air . . , . 77°. 



Temperature of moistened bulb 69° difference 8° x 6=48°. 



Leslie's Hygrometer 103°. 



Mason's Hygrometer 48° — =55°+ Leslie's. 



Being a variation of 55 degrees, produced by the direct 

 rays of the sun falling upon the instrument. 



Experiment 9. — 3 P.M., Instruments as in experiment 1st. 



Temperature of air . . . . 68°. 



Temperature of moistened bulb 61° difference 7° x 6=42°. 



