[ 349 3 
3 7 * pc*“TT — xx+yy — xx dz cc =f ~^ xx + 
— cc-\-ttv>zv — cc + mmzzcc + ttViCG 
ZZtp-\-<P<pXX=Z2CC+ fftAxV — 2pt+ ff zr>zv. 
XX 
38. And t - <p<pxx - <p(px * -( <p(px x- *yy : 
T *J tp-\-ty$XX v T P x p t T 
39 Alfo cQ w 2 + cp ? zr(f^ + // = ) cb X +ca\ 
Jfyy 
CCT 
40. CT ~ q ~ — (tt X — —) — — 
x t tn tn t tox V tt wki/ 
cf f£ cf Cf 
y n Vzi» —Tc 
41. And h--VL = -WL-tm f (for « = ,*). 
1 X tt C<X ptx XX 
ptx 
42 
. AT “ (rfcCT q= CA-) db — — t — - x dz t X ~ dz^f ~ t ~ dz 
ft _ 
(CT + Ctf 
= ) - + /=-x < + Af=— + /r-^- + i. 
t znz. 
43. FT ~ (=fc CT =p cm dz — f— — fLyf l f^S — — — 
m vt J t tn& m x 
fr- (ct-J-c f-£L+f=£tfZ=)I*-zzflz&. 
m n <v cnt m x 
On a a defcribe a circle, draw the tangent TPyand draw CP'* 
Continue dp to p', and at right angles to tp', draw FR', 
Then fr — ( — xcp = — xtx — —)% — fp. 
\ CT X tt 
r . //T x t<V X . 
/> = ^ — xcrr-x/x-r ^ rr/p, 
\ CT a: 
Z z a 
44; DT 
