Page 360 - My FlipBook

356 EXTRACTION OF TEETH.

superior, indeed, to any thing else of the kind. (Fig.
84.) The following is a description of it: "It
consists mainly of two shafts : one is round and
small ; the other is larger, and part round, and part
octagon. Just back of the spiral spring which curves
down at the lancet end, is seen a piece connecting
the two shafts. This piece is soldered fast to the

round shaft, while the upper end of it forms a collar,
in which the round part of the larger shaft slides

Fig. 84.

back and forth, and revolves. On the other end of
the large shaft is seen a screw, made by winding a
wire spirally round it. From the small shaft arises
another, but shorter spiral wire, which, it will be
seen, fits into that upon the larger shaft. The short
one may be considered the nut, in which the other
revolves. The ends of the short spiral are soldered
fast to the small shaft. If, then, the large shaft is
revolved, the screw on it playing in the nut, is
made to slide back and forth, accordingly as it may
be revolved. This motion, then, changes the direc-

tion of the point of the lancet to the plane of the
shafts, any degree from a right angle to a parallel.
Having thus got the inclination which is desired, the