Improved  Troche  Board. 
Am.  Jour.  Pharm. 
Dec,  1879. 
B  C  and  B'  C  are  two  grooves  cut  lengthwise  two  inches  from  their 
respective  sides  of  the  board.  The  grooves  are  each  f  inch  wide,  and 
at  the  ends  B  and  Bf  are  \  inch  deep,  and  at  the  ends  C  and  C  ij 
inch  deep,  thus  giving  a  gradual  incline  from  B  to  C  and  Bf  to  Q  of 
I  inch,  which  gives  an  incline  of  fa  inch  to  each  linear  inch. 
D 
The  bevel  pieces  D  and  E  are  exactly  alike,  34  inches  long,  J  inch 
wide,  and  at  the  ends  x  and  x'  J  inch  thick,  and  at  the  ends  y  and  y' 
f-4+2~IT"l'  mcn  tn'c^j  they  are  10  inches  longer  than  the  board,  and 
should  have  inches,  halves  and  quarters  cut  along  the  sides  of  the  thick 
end  of  each,  so  that  each  can  be  moved  along  its  inclined  groove  any 
exact  distance  and  have  its  surface  at  any  desired  distance  above  the 
surface  of  A. 
When  D  is  placed  in  B  C  with  the  end  x  at  B  it  will  exactly  fill  the 
groove  B  C,  and  its  surface  will  coincide  with  the  surface  of  A,  and  its 
end  y  will  project  from  C  10  inches.  Now,  for  every  inch  that  D  is 
driven  in  the  direction  of  C  B  its  surface  will  be  raised  above  the  sur- 
face of  A  fa  inch.  Hence,  with  this  sized  board,  we  may  get  a  thick- 
ness varying  from  o  to  i|  inch,  which  is  sufficient  for  general  use. 
The  bevel  pieces  should  always  fit  perfect,  and  so  tight  that  a  slight 
hit  with  a  hammer  will  be  required  to  move  them. 
If  greater  thickness  is  required,  a  strip  of  wood  -f^  inch  thick,  or 
even  more,  may  be  placed  in  the  bottom  of  each  groove. 
Boards  made  of  marble,  with  metallic  bevel  pieces  and  roller,  are 
obviously  preferable,  the  sides  of  the  grooves  being  faced  with  lead. 
It  is  absolutely  necessary  that  the  roller  should  be  perfectly  cylindrical 
and  its  surface  straight  and  smooth,  if  accuracy  is  at  all  desired. 
