PROTECTION AGAINST FIRES AND MOVING SAND 29 



Yet even fire lines are by no means a sure prevention against 

 fires nor are fires once under way certain to be arrested by 

 properly laid-out lines, even if fully manned at the time of the 

 conflagration. On the other hand, without fire lines, which are 

 used chiefly to fight from and for ready access, there would be 

 no possibility of successful fighting, and often the lives of the 

 fire fighters would be unnecessarily endangered. 



The cost of these fire lines depends on how they are cleared. 

 For ordinary clearing the rates average 80 to 90 francs ($15.44 

 to $17.37) for the first operation per hectare (2.5 acres) and 

 8 to 9 francs ($1.54 to $1.74) per year thereafter. 



Location. The location of lines has been around boundaries, 

 along main crests, on ridges, and occasionally through large 

 forested areas following slopes or a main divide. The chief 

 arguments given in favor of ridge fire lines, as opposed to slope 

 or valley lines, are that it is easier and hence cheaper to clear 

 the scantier ridge growth, less valuable ground is lost, there is 

 less danger in checking a fire on a ridge, and a ridge fire line 

 can often be used as a general patrol route and occasionally 

 as a logging road. Auxiliary lines often follow roads or trails 

 on a side slope or valley, but these are designed more as a pro- 

 tection from the carelessness of travelers than as part of the 

 general defense. 



Width. The width of fire lines in Tunisia varies from 10 

 to 200 metres (n to 219 yards). There are also lines 20, 50, 

 and 100 metres (22, 55, and 109 yards). Ordinarily boundary 

 fire lines are narrow; 10 to 20 metres (n to 22 yards) is con- 

 sidered sufficient, since the bordering land is usually under 

 partial cultivation or consists merely of heavily grazed brush 

 land. The widest line cleared 200 metres (219 yards) was 

 designed to separate two valuable forests in case of a great fire. 

 Lines designed to divide the ordinary forest and isolate fire are 

 50 metres (55 yards). In the opinion of the acting director 

 the most serviceable lines are 40 to 50 metres (44 to 55 yards). 

 In his experience he has found lo-metre (n-yard) lines too 

 narrow and 2oo-metre (2i8-yard) lines too expensive to main- 

 tain. Another officer preferred a width of 40 metres (44 yards) 



