16.  €3— €«mi  ■TphiMtisM.  In  each  of  the  figures  illuairaiuig
the  following  rules  the  axis  of  projection  is  represented  by  X  X ;
and  in  general  the  part  of  the  figure  above  that  line  represents
the  rabatment  of  the  vertical  plane  of  projection,  and  the  part
below,  the  horizontal  plane  of  projection.  The  projections  of
points  on  the  horizontal  plane  are  in  general  marked  with
•capital  letters,  and  the  projections  on  the  vertical  plane  with  small
letters.
17.  CMtw  (in  fig.  3),  tiM  TimM%  A,  6,  mt  m,  Stniicht  XJm.  M
itamw  te  Fp^i««ttoa*«— From  A  and  5  let  figJl  A  a  and  h  B  perpen-
<licnlar  to  X  X     Then  a  will  be  the  vertical  projeotion  of  the

Digitized  by  VjOOQIC


BULES


XJNES.
» A,  «iid  B  iiw  ^QflMitRl  pn^eolKni  of  the  'taaoe  &    Jodn  »  6,
A  B;  these  will  be  the  projections  required.
(ItmajkflKe  be  roDQarirail^  tktAm  A^aad.ah  mm  the  tniewof  a
pbae  takwauiag  the  gLvoa  liBe,  ani  Mrpaidicnkr  to  tke  -ventiical
pkaeof  pH9Mlaoa.i  widttluiiB  A  md  B&aMiiietneeftef  aj^ajM
tncfOBBiBg  the  gbpoifiae^jnl  pciiyfiBJinnlir  its  Ifa  hmsoBlid  pkoM
ofpg^iefllHB.)

^ig.^  diejfciiiriii.ih  A  B,  •  ft,  •rxi  1^1
laapilB,  wJn-Mi  Ihii  gipqnpwje<^feioBa
meet  tfat  jbb%  dxaw  «  A  and
B  6  pwrpawMffidar  to  X  X,  ont*
tnif^tbB  gicpesL  pvojeotioiis  in  A
and 6 jeepxlivoi^^  Thesepouds
viH  be  the  Te^paatdtraoefl.
19.  CHtcb,  tlM  PMjectloM  m€

cw«  p^tat..  A,  a,  B,  6  (fig.  4),

Amm.— Join  a  6,  A  B;  these  will

be  the  projections  c^  the  straight

line  to  be  measured.     Through  Sig^  &.
