80 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



stop overcoming momentum and always ensuring sections of exactly the 

 thickness called for; which is. <>i' course, a very essential feature. Thi 

 feed pawl is automatically lifted free from the teeth of its ratchet-wheel 

 on the return stroke, thus avoiding wear and the accompanying noise. 

 There arc special arrangements for avoiding injury to thread of feed 

 when the nut has reached its limit and for resumption of cutting. The 

 up-and-down stroke of the object clamp is 2 in. The whole of the 

 feeding mechanism is covered thus protecting the wearing parts from 

 dust, and presenting a much neater apparatus (figs. 12, 13). 



New Spencer Cylindrical Ribbon-carrier.* -This apparatus, which 

 is shown in fig. 14. has been made after C. E. McClung. The 



Fig. 11. 



aluminium cylinder is mounted in an aluminium framework, under the 

 base of which are little rollers rotating in the direction of the long 

 dimension of the frame. The end of the ribbon adheres to the cylinder, 

 which is slowly turned by the little buttons at the end as the ribbon 

 lengthens. At the same time the cylinder and frame are gently pushed 

 forward on the recess so as to place the ribbon on the cylinder in a long 

 spiral. The cylinder is 4i in. long and 2£ in. in diameter. 



* Spencer Microscopes and 

 83 Wigmore Street, London, W. 



Accessories, 1914. Buffalo, New York, and 



