182 



HOW WE PRODUCE ELECTRICITY 



2. How can you take electrons away from a glass rod? How 

 can you add electrons to an insulated piece of metal? 



3. Why does a person become charged with electricity when 

 scuffing over a carpet on a day when the air is dry? 



4. Why is a spark sometimes produced when one rubs the cat's 

 fur backwards? 



REPORTS ON OUTSIDE THINGS I HAVE READ, DONE, 



OR SEEN 



1. Report upon an article related to some topic discussed in 

 this unit. The article may be from a current number of a science 

 magazine or from some popular science book you have read. 



2. The story of Galvani and Volta. 



3. What Benjamin Franklin did for electricity. 



4. The use of lightning rods. 



5. The passing of the magnetic compass on ships. 



SCIENCE RECREATION 



1. THE OBEDIENT ARROW 



Procure a dry fish globe. Cut a cover for it from cardboard. 

 Cut an arrow from stiff letter paper. Suspend the arrow, carefully 



cctrctboarcC 



balanced, in the middle of the 

 globe by a very fine thread. 

 Fasten to the center of the card- 

 board cover. Tell the arrow to 

 turn to the point on the jar 

 which you rub. Rub the outside 

 of the glass up and down at a 

 place about two inches to the 

 right or left of the place where 

 the arrow points, then rub another 

 Pl ace a f ew inches away. Rub 

 your hand over the place elec- 

 trified if you wish to take the 

 electricity away and let the arrow go back to its original position. 



2. A BALLOON WELCOME 



Blow up a rubber balloon until it is about eight inches to ten 

 inches in diameter. Tie tightly. Suspend by a string about 

 three feet from the wall and nearly in the path of a person who 

 comes through the door into the room. It should be shoulder 

 high. On a day when the air is very dry (a cold winter day is best) 



