Every  logician  and  every  economist  will  allow  that  if  you  arrive,
from  different  premises  or  data,  at  the  same  conclusion,  it  is  cumu-
lative testimony,  and  the  probability  of  your  conclusion  being  correct
is  as  high  as  any  evidence  of  fact  can  make  it.  Now  I  arrived  at  my
conclusion  as  to  the  population  of  England  and  Wales  during  this
long  period  by  three  processes.  The  first  was  derived  from  the  rate
of  production.  The  average  production  of  wheat  from  cultivated
land  was  eight  bushels  an  acre,  and  I  came  to  the  conclusion  that
the  possible  average  wheat-growing  acreage  of  the  country  was  three
Trillions.  Now  I  knew  that  a  quarter  of  wheat  every  year  for  every
person,  especially  at  a  time  when  other  vegetable  products  fit  for
human  food  were  unknown,  was  a  fair  allowance.  Then  deducting
one-sixth  for  seed,  I  got  my  two  and  a  half  millions,  as  the  maximum
population,  with  a  high  probabiUty,  as  the  allowance  for  seed  is
rather  short,  that  two  and  a  quarter  is  the  more  correct  figure.  Next
I  took  the  figures  in  the  poU  tax  of  1377.  The  tax-paying  popula-
tion can  be  calculated  at  a  little  above-  one  and  a  half  miUions.  Now
adding  a  third  for  the  children,  for  the  tax  is  exigible  on  persons
above  fourteen  only,  and  making  a  liberal  allowance  for  ecclesiastics
and  mendicants,  no  less  than  a  little  over  162,000,  they  being  also
exempt,  you  again  get  two  and  a  half  miUions.  In  the  third  place,
I  compared  an  actual  census  of  a  certain  district  in  Kent,  taken  in'
the  sixteenth  century,  with  the  census  of  the  same  district  in  1861,
and  found  that  it  was  almost  exactly  a  sixth  of  the  later  number.
