Improvement  of  Land  by  Warping. 
109 
between  the  taking  of  the  first  anil  second  specimens  must  have 
deposited  nearly  half  an  ounce  of  warp.  This  being  the  case,  it 
follows,  that  the  land  must  have  received  about  8483  pounds  or 
rather  more  than  3|  tons  of  anhydrous  warp  per  acre  for  every 
foot  in  depth  of  water  that  flooded  it.  This  is  taking  it  at  a very 
low  estimate,  because,  in  the  present  instance,  there  was  much 
fresh  water  in  the  river,  and  consequently  the  water  contained  less 
warp  than  usual.  In  good  warping  seasons  the  water  of  the  rivers 
Trent  and  Ouse  is  often  so  excessively  muddy,  that,  if  a cylindrical 
glass  tube  of  12  or  15  inches  in  height  be  filled  with  it,  there 
will  be  obtained  an  inch  of  sediment  in  less  than  half  an  hour. 
An  instance  occurred,  a few  years  back,  where  a portion  of  the  old 
channel  of  the  Ouse,  containing  800  acres,  was  deserted  by  an  al- 
teration in  the  drainage,  and  it  was  warped  up  to  the  height  of  25 
feet  in  less  than  six  years,  without  any  artificial  aid  whatever. 
The  question  may  be  asked,  Whence  does  this  warp  or  mud 
come  from  ? That  it  is  not  brought  in  by  the  sea  is  evident, 
because  the  water  at  the  mouth  of  the  Humber  is  perfectly  clear 
and  limpid ; neither  does  it  originate  from  land-floods,  for  these 
are  always  observed  to  injure  the  quality  of  the  warp ; it  there- 
fore can  only  arise  from  the  action  of  the  tidal  waters  upon  the 
strata  of  soft  shaly  clay,  which  form  the  bottom  of  the  Lincoln- 
shire marshes,  and  in  which,  in  all  probability,  the  estuary  of  the 
Humber  has  itself  been  excavated:  the  organic  matters  being 
clearly  derived  from  the  cultivated  land  through  which  the  rivers 
pass.  The  truth  of  this  conclusion  is  moreover  confirmed  by  the 
analyses  (B),  which  exhibit  a composition  exactly  similar  to  that 
we  should  expect  it  to  possess  were  it  formed  under  such  circum- 
stances. The  composition  of  the  warp,  however,  is  very  liable  to 
vary  according  to  the  season  of  the  year  and  the  state  of  the 
weather.  Thus,  in  very  rainy  or  rough  weather  it  generally  con- 
tains a large  proportion  of  coarse  rocky  debris , which  is  useless, 
if  not  injurious ; and  in  the  hot  summer-months,  there  is  a great 
increase  to  be  observed  in  the  quantity  of  common  salt  and  other 
saline  matters  in  consequence  of  the  rapid  evaporation  of  water 
from  the  surface. 
Although  the  proportion  of  the  really  active  fertilizing  ingre- 
dients present  in  the  warp  is  shown  by  the  above  analyses  to  be 
comparatively  small,  still,  if  we  consider  for  a moment  the  large- 
ness of  the  quantity  of  the  warp  applied  to  the  land,  we  shall  not 
fail  to  perceive  that  it  is  far  from  being  contemptible — it  must 
indeed  be  positively  immense.  Thus,  if  we  take  as  data  the 
composition  of  the  warp  as  exhibited  in  the  second  analysis 
(B.  II.),  and  the  average  depth  at  18  inches,  we  shall  find  the 
weight  of  deposit  per  acre  amount  to  about  2829i  tons,  containing 
of  real  anhydrous  constituents  1 485 A tons;  namely,  of — • 
