68 
ME.  HOENEE  ON  THE  ALLIJVIAIi  LANE  OE  E&TPT. 
been  found,  such  as  fragments  and  particles  of  burnt  brick  and  pottery,  and  in  the  area 
of  Heliopolis  and  Memphis,  fragments  of  statues  and  other  sculptured  stones. 
Circumstances  which  modify  the  deposition  of  the  sediment  in  different  parts  of  the  valley. 
When  the  Nile  first  enters  Egypt  at  Assouan,  it  is  loaded  with  its  greatest  amount  of 
solid  matter,  and  with  that  which  is  coarsest  and  heaviest.  In  its  progress,  the  heavier 
particles  must  be  first  deposited,  and  the  solid  matter  thus  becomes  finer  and  finer  as  the 
river  flows  downwards,  until  at  length  it  is  in  the  state  of  an  impalpable  powder,  which 
discolours  the  water,  and  is  perceptible  in  the  sea  at  a great  distance  from  the  land.  As 
a proof  of  the  more  rapid  deposition  of  the  heavier  particles,  even  so  low  dovrn  as  Cairo, 
I may  mention,  that  at  the  ebb  of  the  river,  after  the  inundation  of  1853,  it  was  found 
that  the  deposit  on  the  Mastaba,  or  landing-place,  of  the  Ehoda  Nilometer,  that  is  at 
the  ninth  cubit  mark  on  the  column,  was  6 inches  in  thickness ; on  the  fourth  step  above 
it,  about  2^  inches,  and  on  the  sixteenth  step  not  more  than  1|-,  each  step  being  rather 
more  than  9 inches  deep. 
The  deposition  of  the  sediment  must  further  be  hastened  in  the  upper  parts  of  the 
river  by  two  causes,  the  small  amount  of  the  fall  and  the  evaporation  under  a burning 
sun.  The  course  of  the  stream  between  Assouan  and  Cairo,  according  to  the  obsen'a- 
tions  of  Russeggee,  is  555  statute  miles* * * §,  and  Assouan  being  300  feet  above  Cairo f, 
the  mean  fall  of  the  river  is  thus  6 ’486  inches  according  to  Russeggee,  6T75  according 
to  Hekekyan  Bey,  in  a mile.  The  inundation  of  1851  rose  to  the  height  of  78  feet  at 
the  parallel  of  Memphis,  and  to  63^  feet  at  the  apex  of  the  Delta,  difference  14-|  feet, 
and  the  distance  between  the  two  points  being  thirty  miles,  it  gives  a fall  of  5 ‘8  inches 
in  a mile.  From  Assouan  to  Cairo,  the  river  has  nowhere  a sufficient  fall  to  be  used  as 
water  power  J.  The  evaporation  by  the  great  heat  in  those  latitudes  from  the  broad 
surface  of  the  river  must  be  very  great.  M.  Gieaed  states  §,  that  on  plunging  a ther- 
mometer into  the  sand  that  covers  the  surface  of  the  desert,  it  rose  to  56°  of  Reaumue, 
or  158°  of  Faheenheit ; and  Sir  G.  Wilkinson  says||  that  “so  rapidly  does  the  ardent 
sun  of  Egypt,  even  in  the  months  of  November  and  December,  dry  the  mud,  when  once 
deprived  of  its  covering  of  water,  that  no  fevers  are  generated,  and  no  illness  \isits  those 
villages  which  have  been  entirely  surrounded  by  the  inundation.”  The  evaporating 
water,  thus  parting  with  its  solid  contents,  must  greatly  accelerate  the  deposition  in  the 
higher  parts  of  the  river’s  course.  There  is  also  a constant  soiu’ce  of  irregularity  in  the 
amount  of  deposition  at  different  parts  of  the  valley  from  this  cause,  that  the  Nile  fre- 
quently undermines  its  banks,  and  a vast  quantity  of  the  sediment  of  former  years  falls 
* Eeisen,  Band  ii.  Theil  i.  271, 120  German  geographical  miles,  one  mile=4|-  and  25  yards,  English.  Heke- 
KTAN  Bet  considers  Exjsseggee’s  estimate  to  be  under  the  truth,  and  that  following  the  chief  line  of  cur- 
rent of  the  Nile  (say  its  line  at  low  water),  the  total  distance  from  Assouan  to  the  point  of  Elioda  Island 
must  he  583  miles. 
t Id.  282  Paris  feet. 
§ Memoires  de  I’lnstitut,  1817,  p.  286. 
X Id. 
II  Ancient  Egyptians,  2nd  series,  i.  37. 
