THE RAMSDEN DIVIDING ENGINE.* 



By J. Elfreth Watkins, Curator, Section of Trausportation and 

 Engineering, U. S. National Museum. 



The circle is a figure that Las always been found in nature. 



Although this simple geometrical figure has been used in inscrip- 

 tions and for decoration from time immemorial, I have been able to dis- 

 cover only one very early reference to a pair of compasses, or dividers. 



In referring to the graven images, the worship of which was forbid- 

 den by the Jewish law, the Prophet Isaiah, in chapter 44, verses 12, 13, 

 old version, describes the manner in which these idols were constructed, 

 as follows : 



" The smith with the tongs both worketh in the coals and fiishioneth 

 it with hammers - - -." ''The carpenter stretcheth out his rule; 

 he marketh it out with a line ; he fitteth it with planes and he marketh 

 it out with a compass and maketh it after the figure of man." 



In the revised version the phrase is translated — 



" The carpenter stretcheth out a line ; he marketh it out with a pen- 

 cil ; he shapeth it with j)lanes and he marketh it out with the com- 

 passes and shapeth it after the figure of a man." 



The Hebrew word which is here translated "compass" or "com- 

 passess," is mehugah, from hug, a circle — meJwu something to make a 

 circle. 



There can, therefore, be little doubt that wu instrument for drawing 

 circles and probably similar to what is now known as the " compasses" 

 was used by the Hebrew mechanics. Even if we accept the theory of a 

 deutero Isaiah, this instrument can certainly claim the respectable an- 

 tiquity of the sixth century b, c. 



The circle was associated with the measurement of time and the ob- 

 servation of the positions of the heavenly bodies many centuries before 

 the Christian era. 



THE SUN-DIAL AND GNOMON. 



The sun-dial of Ahaz, is thus alluded to in Isaiah, chapter 38, verse 8, 

 old version, " Behold, I will bring again the shadow of the degrees, 

 which is gone down in the sun-dial of Ahaz, ten degrees backward. So 

 the sun returned ten degrees by which degrees it was gone down." 



"Deposited in the U. S. National Museum by Dr. Henry Mortou, president, Stevens 

 Institute of Technology, Hoboken, New Jersey. 



A. Mis. 129-^ — 40 7^1 



