ae oe 
is made of a piece of brafs hammered about it, and capable of 
being more or lefs clofed at (0) by the ferews (ge); the ends 
of this brafs focket are rivetted at (ff) to the folid piece (4), 
which fits the hole of the reft of a common clockmaker’s 
turn-bench. 
Tue bar (4) is joined to one fide of the vice (aa), and ex- 
tends acrofs to the knife which drops into the cut (¢) in the 
bar, and is thus kept fteady and parallel to the vice. 
Tue fteel of which is to be made the original tap is to be 
prepared as at (x x), the end is to be truly turned and polifhed, 
and at the diftance of the length of the cylinder (ee) a part of 
it is to be turned truly cylindrical, with two fhoulders, be- 
tween which the wire of the fize defired is ‘to be lapped as 
tight and as clofe as it will go, taking care that the threads 
do not run too obliquely, but making them at each revolu- 
tion advance on the fteel cylinder only their own thicknefs. 
A sit of lead about double the Iength of the jaws of the 
vice, and about the tenth of an inch thick, is now to be bent 
about the wire on the fteel; the tool is to be fixed in the place of 
the reft of the turn-bench, and pufhing it near the fteel wire, the 
vice is to be faftened on the lead fo tight as to make on it 
an impreflion of the thread. The knife is then to be let down 
into the notch of the bar (4), and the cylinder (ee) is to be 
adjufted parallel to the fteel. The edge of the knife will touch 
the end of the fteel, the weight (r) being hung on the hook, 
and when the fteel is turned about by the hand, or by a 
bow, 
. 
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