Figure 41. — About 1775: Ford, VVhitmore and Brunton made and sold clockmaker's braces of 

 metal with a sweep and shank that was imitated by American patentees in the 19th century. 

 (Catalogue of Ford, VVhitmore and Brunton, Birmingham, England. Courtesy of the Birmingham 

 Reference Library.) 



IZO-i 



Figure 42. — 1852: Nearly one hundred years after 

 Roubo's plate appeared, Jacob Swilzer applied for a patent 

 for an "Improved Self Holding Screw Driver." The sim- 

 ilarity of Switzer's drawing and Roubo's plate is striking. 

 (Original patent drawing 9.457, U.S. Patent Office, Record 

 Group 241, the National Archives.) 



208 



BULLETIN 24 1 : CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



