526 



MACHINES, WORK, AND ENERGY 



first. In 1851, Mr. A. B. Wilson invented a rotary-hook 

 machine, the first of that type, which was very successful. 



ROTATING HOOH 



3. Under thread enclosed by needle thread. 4. Stitch completed. 



FIG. 327. How a rotary hook makes the knot. 



Figures 326 and 327 show the way in which the rotary-hook 

 machine forms the stitch. 



In the rotary-hook machines, the hook makes one complete 

 rotation for each stitch. 



