56 



Popular Science Monthly 



In their new Alabatross destroyer, which is probably the fastest fighting machine on the 

 machines and have added improvements of their own. A stationary engine of 175 horse- 



Why is the lower win>^ narrower than 

 the upper? There is a kind of interference 

 between upper and lower wings. The air 

 is "caught," as it were, between the 

 superposed surfaces, if the lower wing is 



narrowed this interference is largely pre- 

 vented. But there are structural reasons, 

 too, for narrowing the width of the lower 

 plane. Note in the drawing that the 

 struts are triangular in form and that the 



