the site of the Simeon North arms factory which 

 rivaled Whitney's. In this atmosphere, it is reason- 

 able to expect that machinery constructed by local 

 mechanics, as was the custom in those days, would 

 reflect the most accepted refinements in machine 

 design. 

 Roughly twenty years later, Joseph Nason of New 



Figure 12. — Well-developed example of 

 lathe headstock having several leads on the 

 spindle and provision for mounting the work 

 or a work-holding chuck on the spindle. 

 Adapted from U Encyclopedic, vol. 10. plate 1 3. 



York patented i the commercially very important 

 "Fox" brassworker's lathe (fig. 18). While this docs 

 have a ratio in the pair of gears connecting the work 

 spindle and master screw, it is clear from the patent 

 that various pitches are to be obtained by changing 

 screws, not by changing gears. The patent sums it 

 up as follows: 



A nut upon the end of the stud ... is unscrewed 

 when the guide screw is to be removed or changed. The 

 two wheels . . . should have in their number of teeth a 

 common multiple. They are seldom or never removed 

 and their diameters are made dissimilar only for the 

 purpose of giving to the guide screw a slower rate of 

 motion than that of the mandrel whereby it may be 

 made of coarser pitch than that of the screw to be cut 

 and its wear materially lessened. 



The introduction of gearing between the spindle and 

 the lead screw, for whatever purpose, could not help 

 but introduce variable factors caused by inaccuracies 

 in the gears themselves and in their mounting. These 

 were of little consequence for common work, particu- 

 larly when coupled to a screw which, itself, was of 

 questionable accuracy. The increasing refinements 

 demanded in scientific instruments and in machine 

 tools themselves after they had reached a relatively 



4 U.S. patent 10383 issued to Joseph Nason of New York, 

 January 3, 1854. 



Figure 14.- — Spindle of figures 12 and 13, showing the several 

 leads and the many-sided seat for the driving pulley. Note 

 the scale of feet. From UEncyclopedie, vol. 10, plate 16. 



Figure 13. — End view of the headstock seen in figure 12, showing the keys 

 or half nuts which engage the threaded spindle, in engaged and disengaged 

 positions. From V Encyclopedic, vol. 10, plate 13. 



14 



BULLETIN 240: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



