8 THE SUN, STARS, AND PLANETS 



measure any part of a revolution r or a circle, it has been 

 divided into 360 parts called degrees. A degree means 

 a step. The number 360 was chosen because it can be 

 divided evenly by so many numbers. See if it can be 

 divided by 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12. Try divid- 

 ing 360 by other numbers. A semi-circle divided into 

 180 degrees is called a protractor. It is used to measure 

 the part of a revolution, or circle, which one direction 

 turns from another direction. The short and proper way 

 of writing "degrees" is to use a little circle after the num- 

 ber. For example, 75 degrees may be written 75. This 

 means 75 parts of a circle. 



5. Other Directions. 



If you face the north, the south is behind you ; the 

 east is at your right and the west is at your left. These 

 four points of direction are each a quarter of a revolution, 

 or a quarter of a circle, from the next one. How m^ny 

 degrees between any two of them? How many degrees 

 between the north and the south. If one direction is 181 

 dgrees from another direction the two directions are said 

 to be opposite each other. Is the east opposite to the 

 west? Why? 



Experiment 4. To Locate the South by Means of 

 * Watch. 



a. Hold the watch so that the hour hand points 

 toward the sun. The south direction will then be just 

 half way between the hour hand and the figure XII on 

 the watch. Do this both in the morning and afternoon 

 and see if the result is the same. Can you tell where the 

 north is from this experiment? 



