502 



GENERAL SCIENCE 



FIG. 385a. Vibrating Shuttle 

 Sewing Machine. First 

 stage in stitching. 



FIG. 3856. Second Stage, 



d 



FIG. 385c. Third stage. 



FIG. 385d. Completed stitch. 



QUESTIONS 



i 



1. Find some examples in your home of the wheel and axle. 



2. Why is the wheel and axle principle used in the particular 

 things mentioned? 



3. Find an example where pulleys are used, and tell why they 

 are used? 



4. Why is it easier to draw a heavy boat ashore with pulleys? 



