1 8  PREFACE. 
No  one  else  will  feel  so  keenly  the  imperfections  of  this  volume  as  the 
writer.  Papers  will  be  found  to  be  overlooked  of  which  summaries  ought 
to  have  been  made.  Mistakes  of  interpretation  will  be  found.  Undue 
proportion  in  the  summaries  will  be  discovered.  I  can  only  say  that 
I  have  attempted  to  reduce  these  defects  to  a  miuimum.  It  will  be 
esteemed  a  great  favor,  with  reference  to  a  possible  future  edition,  if 
all  who  discover  such  omissions  and  mistakes  will  communicate  them 
to  the  writer. 
c.  e.  v. 
Madison,  Wis.,  July,  31, 1891. 
