Dr. Chowne on the Movement of Atmospheric Air in Tubes. 235 



In the first experiment, the tube and bell-glass previously described 

 (fig. 1 8) were employed, but substituting folds of damp linen for the 

 saucer of sulphuric acid, so as fully to charge the air in the bell- 

 glass with vapour, the rotations rapidly rose from 4'0 to 17 or 18 

 per minute. 



But as the cold produced by the evaporation of the water in this 

 experiment might be a source of fallacy, an arrangement was made 

 (fig. 19) to supply the bell-glass with air, previously charged with 

 vapour, formed at a distance of 5 feet from the glass. The rapidity 

 of the revolutions was however still considerably increased. 



Augmentation of the quantity of aqueous vapour, in the general 

 atmosphere of the room, by spreading wet cloths on the floor and 

 other parts, also produced increase in the rapidity of the rotations, 

 though to a small extent. 



Fig. 19. 



Z, Z, Z. Tubes containing wet linen within their remote extremities. 



These experiments* would seem to demonstrate that the ordi- 

 nary condition of atmospheric air within vertical tubes, open at both 

 extremities, is one of continual upward movement. 



If the atmosphere were a strictly homogeneous elastic fluid, and 



* Throughout the entire series the results were carefully observed during the 

 night, wlien the atmosphere of the room was free from solar influences. The dry- 

 and tiie wet-bulb thermometers yielded the same relative differences, and the discs 

 rotated with the same constancy. Tiic night as well as the day observations were 

 continued through all the clianges of temperature, from March 1853 to the present 

 time. 



R2 



