50 



Popular Science MnufhJif 



2 



The wind which is 

 customarily ob- 

 served is tli.it in- 

 dicated by the fly 

 at the masthead. 

 The fly generally 

 shows the skipper 

 the apparent di- 

 rection in which 

 the wind is blow- 

 ing. Professor 

 Everett made ex- 

 periments in a 

 wind tunnel which 

 show that yachts- 

 men do not fully 

 appreciate the 

 mechanical forces 

 at work 



The apparent 

 wind is the result- 

 nnt of the speed 

 '<( the boat and 

 ihc true wind 



