Figure 5.' — Spring for keeping the follower spindle against the work, showing the method 

 and range of adjustment. Note the rectangular projection to engage a mating socket in 

 the pindle, to prevent spindle rotation. (Smithsonian photo 46525.) 



Figure 6. — Work SPINDLE and its NUT removed from the machine to illustrate how easily 

 another spindle and nut of different pitch could be substituted. (Smithsonian photo 

 ,.,-,250 



necessary to keep the tool cutting as the end of the 

 thread was approached. 



That machines of this general type having the lead 

 screw on the axis of the work were competitive with 

 Othei methods and other types of machines over a 

 long period of time ma) l>e seen from figures 9 and 

 10. The machine, left front in figure 9 and in more 

 intimate detail in figure 10, can be seen to differ 

 little from thai shown in Dai mittelalterliche Hausbuch 



of 1483. The double work-support is, of course, a 

 great improvement, while the tool-support is regres- 

 sive since it lacks a feed screw. 



The development of engineering theory, coupled 

 with the rising needs of industry, particularly with the 

 advent of the Industrial Revolution, brought about ac- 

 celerated development of screw-cutting lathes through 

 the combination of screw-cutting machines with sim- 

 ple l.i 1 hes .is seen in figure 9 and in detail in figure 1 1 . 



Ill 



bulletin L'lti: cox TkinrnoNs from the museum of history and technology 



