10 Gibson, Draught produced by an Inclined Rod. 



The action becomes very apparent if a sheet of 

 blotting paper moistened in sections with Hquid ammonia 

 and with hydrochloric acid be wrapped tightly around'the 

 poker, the dense white fumes which are then given off 

 enabling the direction and apparent velocity of the current 

 to be readily observed. 



Under the conditions already described such observa- 

 tions showed that with a gentle horizontal blast and 

 with a poker inclined at 50" this directive influence was 

 felt over a region apparently about 3" in diameter, 

 extending from about f " above to 2Y below the poker. 

 Over this region the mean direction of the draught was 

 inclined at about 30' to the horizontal. 



