DESCRIPTION  OP  PHARMACEUTICAL  APPARATUS. 
29 
shaft  and  connections.  The  pestle  has  a  long  rod  passed,  at  C, 
through  a  universal  joint  in  a  weighted  lever,  arranged  to  give 
the  proper  pressure  to  the  pestle.  The  top  of  the  pestle-rod  is 
inserted  into  a  small  sliding  block,  D,  grooved  to  slide  along  a 
short  guide-bar,  as  shown  in  the  detail,  fig.  3.  This  bar  is  fixed 
to  the  side  of  the  bevel  wheel,  E,  running  loose  on  a  vertical  stud, 
and  driven  by  the  large  wheel,  F,  fast  on  the  driving  shaft,  which 
receives  its  motion  from  a  winch-handle.  A  spur-wheel,  G,  runs 
on  a  stud  carried  by  an  arm,  attached  to  the  wheel,  E,  and  gears 
with  a  pinion  on  the  shaft  of  the  spur-wheel,  H,  which  latter 
gears  with  a  stationary  pinion,  I,  fast  on  the  stud  centre  of  the 
bevel  wheel,  E.  A  rod,  L,  connects  the  block,  D,  to  a  pin  in  the 
face  of  the  wheel,  G,  and  thus  the  revolution  of  this  wheel  causes 
the  rod  of  the  pestle  to  be  continually  traversed  backwards  and 
forwards  across  the  centre  line  of  the  wheel,  F,  directly  over  the 
mortar  beneath.  This  gearing  involves  the  principle  of  the  old 
"  sun-and-planet "  motion,  and  gives  to  the  pestle  a  most  effec- 
tive rubbing  action  in  a  compound  revolving  and  traversing 
movement. 
The  original  idea  in  contriving  this  triturator,  was  to  provide 
some  more  effectual  plan  for  grinding  sheep  ointment,  but  its 
success  has  led  to  its  extended  use  for  all  triturating  purposes 
and  levigating  operations.  Small  machines  are  also  manufac- 
tured with  movable  wedgewood  mortars  and  pestles,  scraper  and 
light  iron  framing  of  various  sizes,  suitable  for  druggists,  &c. 
Patent  Heat-Regulating  Plaster  Spatula  This  instrument, 
invented  by  Mr.  Stockton,  of  3  Gray's  place,  Brompton,  (Eng.) 
we  find  figured  in  the  Pharmaceutical  Journal  for  November. 
Although  rather  complicated,  it  presents  several  advantages 
worthy  of  notice,  the  chief  of  which  is  the  perfect  control  the 
operator  has  over  the  heat.    The  following  description  we  copy  • 
3* 
