288 NATURE STUDY REVIEW [9:9— Dec, 1913 



more needed in the rain. If there be many kinds of materials 

 available some sort of division of labor may be arranged for 

 the collecting of it. 



2. The materials gathered should be carried out to an 

 open space on the lee side of the woods, and tried out in fire- 

 making. Let the fires be so arranged as to secure a minimum 

 of inconvenience from smoke. Each student should make a 

 small fire (not over i8 inches in diameter) using one kind of 

 material only. Let those more experienced at fire making 

 try more difficult materials, — say green elm, for a climax. Let 

 each effort result in a fire and not a smudge : It should catch 

 quickly and burn up steadily and clearly with little smoke. 

 To this end materials ^ 



should be selected of proper fo;ilJ;;;C|'''^ — ^~^^ — '~ ^~y 



kind and proper size for 



I • •,• , 1 Fig. 4G. A simple rack of bent wire suit- 



ready Ignition, must be so able for the block testing outlined in this 



arranged as to admit air ^^" ^' 



below, must "feed" inward as the center bums out and 



must not be increased in size faster than the increasing heat 



warrants. 



With the individual fires burning steadily let observations 

 be made on the readiness of ignition of other woods, green and 

 dead, wet and dry, sound and punk. Different kinds of bark 

 will show interesting differences in readiness of ignition. 



Demonstrations: At a common fire of larger size a num- 

 ber of demonstrations may be made. 



1. The long-burning qualities of different kinds of wood 

 may be roughly shown by placing pieces cut to like size and 

 form on a wire rack such as is shown in fig. 46, setting the 

 rack upon a broad uniform bed of coals, and noting the time 

 at which each piece is completely consumed. 



2 . The fire holding qualities of the same kinds of wood may 

 be shown by like treatment of a similar lot up to the point of 

 their complete ignition — then removing them from the fire 



