13.  Choose  among  the  bodies  before  you  one  which  has
two  of  its  dimensions  equal.     Which  are  they  ?

14.  Point  out  upon  a  cube  the  intersection   of    two   sur-
faces.    Also  the  intersection  of  two  lines.
15.  How  many  edges  and  how  many  corners  has  a  square
box?

16.  In  common  language,  a  telegraph  wire  is  called  a  line.
Is  it  a  geometrical  line  ?     What  is  it  ?     Why  ?

17.  We  call  the  trace  of  a  pencil-point  on  paper  a  line.
What  is  it  in  reality  ?     Why  ?

*

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8  LESSONS   IN    GEOMETRY.
Lesson  4.
1.  Divide  lines  into  two  classes.    Define  each  class.
There  are  two  kinds  of  lines,  straight  and  curved.
A  straight  line  has  the  same  direction  from  end  to  end.
A  curved  line  is  a  line  whose  direction  is  continually
changing.  Curved  lines  are  often  called  curves.  A  moving
point  describes  a  straight  line  when  the  direction  of  its
motion  does  not  change,  and  a  curve  when  the  direction  of
the  motion  continually  changes.  In  Figure  12,

AB  is  a  straight  line  ;
~B      CD  is  a  curve  ;

EF  is  a  broken  line  ;
GH  is  a  composite  line.
The  figures  on   carpets   and  on
_j.  wall-papers     furnish     numberless
Flo  12  examples    of    broken    and    com-

posite lines.
The  word  "line"  used  alone  means  straight  line.
2.  Draw  and  name  with  letters  two  straight  lines  which
intersect.     Also  two  straight  lines  which  do  not  intersect.
3.  The  same  exercise  with  two  curved  lines.
4.  Draw  three  broken  lines.     Define  a  broken  line.
5.  Draw  three  composite  lines.     Define  a  composite  line.
