16 



THE SUN, STARS, AND PLANETS 



Experiment 10. The Height of the Sun at Noon 

 Measured in Degrees. 



Apparatus: Chalk box, protractor, nail, two tacks, 

 a body of water zero degrees high. We call directly 

 overhead ninety degrees high. 



a. Take an empty chalk box and with the open side 

 toward you tack the protractor so that its straight side 

 crosses the short end of the box half-way and is parallel 

 with the long side. Drive a brad at the center point of the 

 protractor. With your rule held against the brad and 

 over the 85 division, mark the edge of the box with pen- 

 cil. Repeat for each 5. The marks on the edge of the 

 chalk box are not the same distance apart, but a shadow 

 of the nail falls on each mark in succession for each 5. 

 See if this is not true. The apparatus should appear like 

 the illustration. 



b. Place the box so that the shadow of the nail at 

 noon falls. across the protractor and on the edge of the 



