bottom  of  clay,  star-shaped,  to  allow  this  drainage
through  the  points  ;  at  other  times  a  small  receptacle
below  the  bowl  of  the  pipe  receives  the  oil  exuded  in
smoking.  A  glass  tube  to  the  pipe  has  recently  been
introduced,  which  occupies  the  centre  of  the  stem,
and  swells  to  a  considerable  size  in  the  midst  for
the  same  purpose.  Since  then  an  improvement  has
been  invented  in  what  is  termed  the  diaphragm  pipe,
the  enlarged  centre  of  the  glass
tube  being  divided  longitudinally
by  a  glass  partition  (a),  against
which  the  smoke  beats,  the  oil
descends,  and  the  regurgitating  smoke  is  drawn  in  a
purified  state  through  the  smaller  tube  (b),  which
projects  from  the  centre  of  the  division.  A  glass
worm  is  sometimes  made  to  encircle  this  central  pipe,
and  so  give  condensation  to  the  smoke.
