PROJECTS 565 



ical Survey which will show the variation for any section accurately. 

 Only be sure that you have the latest issue of the chart, because the 

 declination of the needle slowly changes from time to time (pp. 

 38, 39). 



Set your compass in a place, as nearly level as possible, away 

 from the vicinity of steel and iron. Then allow for the declination 

 and you will have the true north. 



If you cannot afford a compass, make one as suggested in Exper- 

 iment 8, pages 37 and 38. To use this satisfactorily, you will have 

 to train your eye to gauge the declination. This you can do by 

 floating the cork compass at the side of a manufactured compass 

 as often as you have opportunity. Train the eye to recognize the 

 declination of the floating compass by comparing it with the 

 measured decimation on the manufactured compass. 



Put the cork in your pocket and carry the magnetized needle in a 

 small glass phial. You can set this compass wherever there is 

 water. 



(c) Hard and fast rules for telling direction by the growth of 

 mosses and lichens and other vegetation in forests are responsible 

 for a good deal of current misinformation. Writers sometimes give 

 specific information for certain regions, and amateur woodsmen 

 get the impression that the instructions are true for all times and 

 places. 



Practiced guides, like the Indians of old, can tell direction within 

 a very few degrees of perfect accuracy by observing forest vege- 

 tation. This ability comes of long and acute observation and can- 

 not be cultivated by rule. A few basic facts may be given, along 

 with advice that accurate information for any section can come 

 only of close observation and reasoning. 



As a rule, mosses and lichens grow on the cool or shady side 

 of a tree. In the North Temperate zone, this is generally the north- 

 ern side, but it may vary with the immediate surroundings and with 

 the direction of the prevailing winds and rains. For instance, 

 trees growing on a north slope, where the sun has no access to them, 

 are coolest and dampest on the side toward the ground, and may 

 therefore have moss on the south side. 



