tooth; hence _h_
meets _p_, which is the root of the tooth on the large wheel. To give
clearance and prevent the tops of the teeth on one wheel from bearing
against the bottoms of the spaces in the other wheel, the point of the
pinion teeth is marked below; thus arc _b_ does not meet _h_ or _p_, but
is short to the amount of clearance. Having obtained the arcs _d_, _e_,
_f_, the curves may be marked thereon as for a spur wheel. A tooth thus
marked is shown at _x_, and from its curves between _b_ and _c_, a
template may be made for the large diameter or outer end of the pinion
teeth. Similarly for the wheel C the outer end curves are marked on the
arcs _g_, _h_, _i_, and those for the other end of the tooth are marked
between the arcs _l_, _m_.

[Illustration: Fig. 243. (Page 207.)]

[Illustration: Fig. 244.]

Figure 243 represents a drawing of one-half of a bevil gear, and an edge
view projected from the same. The point E corresponds to point E in
Figure 241, or W in 242. The line F shows that the top surface of the
teeth points to E. Line G shows that the pitch line of each tooth points
to E, and lines H show that the bottom of the surface of a space also
points to E. Line 1 shows that the sides of each tooth point to E. And
it follows that the outer end of a tooth is both higher or deeper and
also thicker than its inner end; thus J is thicker and deeper than end K
of the tooth. Lines F G, representing the top and bottom of a tooth in
Figure 243, obviously correspond to dotted lines _p_ in Figure 242. The
outer and inner ends of the teeth in the edge view are projected from
the outer and inner ends in the face view, as is shown by the dotted
lines carried from tooth L in the face view, to tooth L in the edge
view, and it is obvious from what has been said that in drawing the
lines for the tooth in the edge view they will point to the centre E.

[Illustration: Fig. 245.]

To save work in drawing bevil gear wheels, they are sometimes drawn in
section or in outline only; thus in Figure 244 is shown a pair of bevil
wheels shown in section, and in Figure 245 is a drawing of a part of an
Ames lathe feed motion. B C D and E are spur gears, while G H and I are
bevil gears, the cone surface on which the teeth lie being left blank,
save at the edges where a tooth is in each case drawn in. Wheel D is
shown in section so as to show the means by which it may be moved out of
gear with C and E. Small bevil gears may also be repr