186 METHODS OF COMMUNICATION FOR FOREST PROTECTION 



3 It is slower in operation. This, however, is probably more than offset with 

 poorly trained operators by the fact that once aligned the lantern needs 110 further 

 adjustment. 



4 At mountain lookouts and other stations difficult of access, the providing of 

 sufficient electric cells or other source of light may be inconvenient. 



The signal-lantern, therefore, can be successfully used only as an adjunct to 

 the heliograph in situations where the latter is the principal or only means of com- 

 munication, and only for the purpose of communication between lookout stations or 

 from a lookout to a lowland headquarters on the telephone system. For this purpose 

 a ]amp with a great range, a moderate weight, and a reasonable first cost and power 

 charge is essential. These requirements would seem to be met best by the Fischer 

 triangulation lamp of the United States Coast and Geodetic Survey. 



CHAPTER XXII 



FLAG 



Section 118 General Remarks 



The flag as a means of communication is far less applicable to forest protection 

 than to military operations. Its principal value lies in the extreme simplicity and 

 cheapness of the equipment required 1 , and in the fact that it may be readily impro- 

 vised and can therefore always be available. It is, further, a convenient signalling 

 device with which to instruct new men and keep trained men in practice. The range 

 over which it may be used is so limited, however, that in most forest work the place 

 it might occupy will be taken by either -an emergency telephone line or a messengei 

 service. 



The flag is a day signalling device like the heliograph, but unlike the latter it- 

 can be employed on dull days as direct sunlight is not essential. Dust and smoke, 

 however, very greatly limit the range of flag signals, and may act .as a serious obstacle 

 to their employment. 



Section 119 Equipment Required 



Flags should be of linen or cotton cloth or some similar smooth material. Gala- 

 tea and near-silk serve admirably. The colours used depend on the background 

 ^against which the signals are being made. Dark blue is best for a light background; 

 white with a blue or red strip or square in the centre, for a dark background'. Sizes 

 used depend on the distance, and run from 2-ft. square to 6-ft. square, which latter 

 is about the largest practicable -size. For forest use, it is unnecessary to provide 

 poles, but one edge of the flag should be provided with tapes at intervals of 12-in. by 

 which the flag can be attached quickly to a light pole, cut as required. For tem- 

 porary stations, flags are preferably made of some mercerized' cotton cloth in order 

 to reduce weight and bulk. Two :l-ft. flags of this material can be rolled into a 

 package the size of an ordinary dry cell and will weigh 12 ounces. 



Section 120 Range and Speed 



In military operations, flags are generally read with field-glasses or telescopes. 

 This is seldom practicable in the communication work required in forest protection, 

 The distance at which flags of a given size can be read depends on the nature and 1 

 cdour of the background., the state of the atmosphere, and the power of the telescope 

 employed. The greatest distances are possible on days with -a clear atmosphere but 

 the sky lightly overcast with clouds. Lack of sunlight does not prevent the use of 

 flags as it does the heliograph. 'Smoke and fog, (however, are more or less complete 



