564 EVERYDAY SCIENCE 



Learn to recognize these three northern constellations so that 

 you can trace them readily, and you will be able to locate the North 

 Star without difficulty. Then when you are in a strange locality, 

 the northern sky will seem familiar to you and will guide you 

 unerringly. 



When you have located the North Star, face it with arms out- 

 stretched to right and left. The right arm points to the east; 

 the left arm to the west. 



PROJECT II. How a Boy Scout Determines Directions by Day, 

 pages 23, 24, 37, 38 



(a) To determine directions with the aid of a watch, point the 

 hour-hand toward the sun. To do this accurately, hold the watch, 

 face upward, in the palm of your hand. Hold a match or a straight 

 twig upright at the edge of the dial and turn the watch until the 

 hour-hand points toward the match and the shadow of the match 

 lies directly along the line of the hour-hand. 



The point on the dial halfway between the hour-hand and the 

 figure XII will then indicate south with a fair degree of accuracy. 

 Thus, if the hour-hand is at X, the figure XI on the dial will point 

 toward the south ; if the hour-hand is at III, the mark on the dial 

 that indicates 1 : 30 will point toward the south. 



EXPLANATION. The reason for this is that on a day of average 

 length (twelve hours) the sun appears to describe a half-circle in the 

 sky while the hour-hand of your watch is describing a complete circle. 

 If the watch and the sun both described a semicircle in the same length 

 of time, the figure XII would always point toward the south if the hour- 

 hand were aimed at the sun. But since the hour-hand travels its cir- 

 cuit twice as fast as the sun, it is necessary to halve the distance between 

 the hour-hand and the figure XII in order to find the point on the dial 

 that indicates the south. 



(6) A "reliable pocket compass may be had for a reasonable sum. 

 Learn from some surveyor the declination (p. 38) for your imme- 

 diate section so that you may determine the true north accurately; 

 You may purchase magnetic charts from the United States Geolog- 



