﻿the Micro- Azimometer 



389 



recess A 2 provides sufficient room for the ringers when the 

 setting of the micrometer has to be altered. The "anvil " of 

 the calliper has been removed, and through the hole thus 

 left the link F 3 passes clear. The right-hand end of F 3 



Fiff. 3. Scale 1 : 3'5. 



fZ 



bears directly against the end of the measuring-spindle, and 

 is centred by passing through the cap F 2 . The left-hand end 

 of F 3 is hemispherical, and rests in a conical depression in 

 the side of the flat plate B 1? on which the slit (not shown) is 

 mounted. B x is attached to a tube B, which has been 

 turned truly cylindrical, and rests in V's planed in the two 

 lugs AjAi of the plate A. A screw B 2 is screwed into B x 

 from behind, and the head of this screw is kept in contact 

 with the planed face A 4 by the weight of B and of the slit 

 which it carries. Thus the motion of the system BB X is 

 geometrically limited to displacements to right and left. 



8. A coiled wire spring D passes axially through the 

 tube B r and has one end attached to the pin D 1? its other 

 end being secured to the fixed screw D 2 . The tension of 

 this spring remains fairly uniform throughout the range o£ 

 motion of the micrometer, and is sufficient to ensure that the 

 link F 3 shall be always in compression. Thus F 3 and the 

 slit carried by the plate B x partake of the axial motion o£ 

 the micrometer spindle. The wire W is rixed just in front 



