36     Mr.  J.  E.  H.  Gordon  on  a  new  Anemometer  for  Indicating 
which  the  hand  is  pointing  shall  be  at  the  bottom  of  thetype- wheel. 
Close  behind  this,  and  with  its  lower  edge  coming  a  little  below 
the  lower  edge  of  the  direction  type-wheel,  is  a  wheel  embossed 
with  the  hours  from  I  to  XII.  This  is  fixed  on  the  hour-axis  of  a 
rather  powerful  clock;  a  wheel  of  unpolished  boxwood  is  kept  by 
a  spring  pressed  up  against  its  lower  edge*.  Underneath  the  di- 
rection-wheel, but  not  touching  it,  is  a  little  stamper  faced  with 
boxwood ;  under  the  stamper  is  a  lever,  to  which  is  attached 
an  armature  which  rests  over  an  electromagnet.  Inside  the 
clock,  on  one  of  the  axes  (which  revolves  once  in  an  hour)  is  an 
ivory  wheel  with  two  small  platinum  studs  on  its  edge  oppo- 
site to  each  other;  a  little  spring  with  a  platinum  point  presses 
on  its  edge.  This  is  connected  to  the  stamper-magnet,  and  at 
each  half  hour  sends  through  it  a  current  of  about  two  seconds' 
duration,  which  presses  the  stamper  up  against  the  direction 
type-wheel.  The  paper  is  wound  on  two  large  reels  ;  it  consists 
of  a  continuous  band  of  white  paper,  and  a  similar  band  of  black 
copying-paper.  The  two  papers  were  at  first  wound  together  on 
one  reel ;  but  it  was  found,  when  they  had  been  together  for  some 
time,  that  the  oil  from  the  black  paper  soaked  into  and  dirtied 
the  white  paper.  To  avoid  this  Mr.  Apps  has  arranged  to  wind 
the  papers  on  separate  reels,  the  reel  of  black  paper  being  placed 
immediately  above  the  reel  of  white  paper.  The  papers  pass 
between  the  hour  type-wheel  and  its  spring  roller.  The  clock 
as  it  turns  draws  the  papers  through  (the  black  being  uppermost), 
and  prints  off  the  hours  on  the  white  paper.  Each  half  hour 
the  stamper  is  raised  and  prints  off  whatever  letter  on  the  di- 
rection-wheel is  at  the  bottom  at  the  moment. 
The  stamper,  however,  continues  raised  for  nearly  two  seconds. 
If  the  wind  were  to  change  during  that  time  the  lever  would  not 
be  able  to  move  the  hand,  as  it  would  be  jammed  by  the  stamper. 
To  avoid  this  source  of  error,  the  current  which  works  the  driving- 
magnets  is  made,  on  its  way,  to  pass  round  another  little  magnet ; 
the  armature  of  this  magnet  is  kept  by  a  spring  against  a  pla- 
tinum point.  The  current  which  works  the  stamper-magnet 
has  on  its  way  to  pass  from  this  point  to  the  armature.  Sup- 
pose the  stamper  to  be  raised  and  a  current  to  pass  round  one 
~>f  the  driving-magnets ;  it  passes  round  the  safety-magnet,  pulls 
the  armature  away  from  the  platinum  point,  breaks  the  current 
in  the  stamper-magnet,  releases  the  stamper,  and  allows  the 
hand  to  move  (see  fig.  6) . 
The  Force- apparatus. 
The  contact-breaker  is  shown  in  plan,  fig.  5.    It  consists  of  a 
set  of  Robinson's  cups,  connected  by  the  usual  gearing  to  a  box- 
*  See  note  at  end  of  paper. 
