420 



Transactions of the Society. 



To meet this difficulty I have added a means by which the tension 

 of the spring may within considerable limits be controlled. A milled 



Fia. 103. 



P, Pillar. F, Fulcrum of lever. R, Steel roller on which the lever 

 bears. M, Milled head controlling tension of the spring. C, Coarse 

 adjustment pinion. 



screw M, seen just behind the coarse adjustment, passes into the hollow 

 pillar and terminates in a plug which bears upon the spring. Wheu 



