It  is  to  Mr.  Watt,  as  is  well  known,  that  we  are  indebted  for
the  most  important  developments  of  the  theory  of  latent  heat,
which  were  made  the  basis  of  all  his  great  improvements  in  the
construction  of  the  steam-engine :  there  is  no  other  example
equally  remarkable,  of  the  prompt  application  of  a  great  philoso-
phical truth  to  the  most  important  improvement  of  the  powers  and
application  of  machinery  which  is  to  be  found  in  the  annals  of  the
arts;  there  is  none  which  is  equally  honourable  to  its  author.
It  would  appear  that  Lord  Brougham  was  known  to  Dr.  Black
through  his  maternal  grand-uncle.  Dr.  Robertson  the  historian ,
and  attended  his  lectures  when  a  student  in  the  University  of
Edinburgh,  a  circumstance  which  may  be  allowed  to  excuse  a
very  favourable  view  of  his  character  and  discoveries,  though  it
cannot  justify  the  extraordinary  succession  of  inaccuracies  and
exaggerations  which  this  sketch  of  his  life  contains,  a  very  few
only  of  which  we  have  had  occasion  to  notice.  The  following
account  of  his  style  of  lecturing,  and  of  the  impression  which
it  produced  upon  his  auditors,  is  in  Lord  Brougham's  best
manner :

*It  remains  to  consider  him  as  a  teacher;  and  certainly  nothing
could  he  more  admirable  than  the  manner  in  which  for  forty  years  he
performed  this  useful  and  dignified  office.  His  style  of  lecturing  was  as
nearly  perfect  as  can  well  be  conceived ;  for  it  had  all  the  simplicity
which  is  so  entirely  suited  to  scientific  discourse,  while  it  partook  largely
of  the  elegance  which  characterized  all  that  he  said  or  did.  Nothing
could  be  more  suited  to  the  occasion;  it  was  perfect  philosophical
calmness ;  there  was  no  effort ;  it  was  an  easy  and  graceful  couversation.
