There  are  many  practitioners,  however,  who,  although  in  other  respects
competent,  have  not,  in  the  mechanical  department,  enjoyed  this  advan-
tage, and,  consequently,  it  is  to  be  regretted  that  he  has  not  entered
more  into  detail  upon  the  subject.  Most  of  the  deficiencies  that  exist
in  the  last-named  work  were  supplied,  up  to  1844,  by  Dr.  Solyman
Brown,  in  his  series  of  pajjers  on  Mechanical  Dentistry,  published  in
the  American  Journal  of  Dental  Science.  These  papers  were  illustra-
ted with  numerous  cuts,  and  constituted,  up  to  the  time  of  their  publi-
cation, the  best  treatise  upon  the  subject.  But  numerous  and  important
improvements  have  subsequently  been  made  in  this  department  of
practice,  all  of  which  we  propose  to  give  a  brief  description  of  in  their
proper  place.
The  only  treatises  upon  Mechanical  Dentistry,  published  in  book
form,  in  this  country,  since  the  papers  of  Dr.  Brown,  have  been  this
division  of  our  own  work  and  the  treatise  of  Prof  Joseph  Richardson.
In  the  dental  periodicals  of  the  past  eighteen  years  will  be  found  many


SUBSTANCES    EMPLOYED    AS    SUBSTITUTES.        491

carefully  prepared  papers  from  the  pen  of  Prof  Austen,  and  others,
which  present  a  great  amount  of  information,  very  valuable  to  the
practitioner.  They  give  also  an  instructive  view  of  the  rapid  progress
made  in  the  dental  art,  and  teach  the  necessity  of  being  constantly
alive  to  the  improvements,  real  or  fancied,  which  are  almost  daily  pro-
posed.
