22 BULLETIN 139, UNITED STATES NATIONAL MUSEUM 



DEVELOPMENT OF DRAUGHT 



Draught is of primary importance in the adaptation of fire to 

 human needs. " In all phases of the fire art some attention has been 

 given to the air supply in combustion, and the plans for control vary 

 from the most primitive to the exact calculated formulas and 

 appliances of the present. The history of the valuable utilizations 

 of methods to increase heat, so important to human progress, is first 

 and chiefly concerned with draught and second with fuel. 



The coals of a simple camp or house fire can be given temporary 

 draught with a fan or such means. When a fire has a sufficient 

 amount of fuel the uprush of heated gas and air currents gives the 

 blaze observed and the necessary draught. 



In a confined fire with charcoal as fuel there is a slow combustion 

 without draught, and any extra heat required may be given by fresh- 

 ening the coals with a fan or blowing tube. With natural wood fuel, 

 however, there is required aeration from below in most cases to insure 

 combustion without too much smoke. 



Draught is classified as: 



1. Natural, in the uncovered fire caused by uprush of heated gas 

 drawing in below displaced air; without design. 



2. Induced, by placement of stones around the fire and a stone or 

 vessels above the fire; by raising the fire above the base level; and 

 regularly piling the fuel. The first steps of designed draught are seen 

 here. 



3. By piercing holes above the fire and a confined vessel; by pierc- 

 ing holes in the bottom of a vessel; by base or under structure giving 

 an air chamber. Later these features are combined in one stove. 



In the simple fire receptacles where small portions of heated fuel 

 are installed, there is no provision for draught. It appears that for 

 a long period no necessity for draught arose aside from simple blow- 

 ing or fanning, as mentioned under bellows, which would be sufficient 

 to brighten the fire for temporary uses. It is found that in the 

 simple fire containers fuel was the important thing, and there is 

 shown to have been a development of fuel leading to the use of char- 

 coal. Charcoal marks a great advance, equivalent at least to an 

 epoch-making discovery. Incidentally the extension of the use of 

 charcoal, giving rise to a demand for this fuel, was responsible for the 

 first inroads on the forests. 



The minor fire vessels mark the first tentative elevating of fire 

 above its primitive base fine and paved the way for the application 

 of draught beneath the fire When charcoal is used as suggested, the 

 necessity for aeration of the fire from below is not pressing, but in 

 the burning of other substances for special purposes it was seen that 

 draught was necessary. Beginnings are observed in burners for in- 



