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ME.  HOENEE  ON  THE  ALLTJVIAE  LANE  OF  EG3ET. 
“ Si  done  il  n’est  point  exact  de  dire  qn’en  un  point  determine  de  TEgypte,  le  fond  du 
lit  du  Nil  et  la  plaine  adjacente  s’elevent  simultanement  de  la  meme  quantite  seculaire, 
il  est  constant  que,  depuis  la  derniere  cataracte  jusqua  la  mer,  le  fond  du  fleure  et  le 
niveau  des  plaines  qu’il  submerge  se  sont  eleves  dune  meme  quantite  moyenne,  puisque 
ces  deux  surfaces  tendent  sans  cesse  au  parallelisme,  et  que  la  nature  les  y ramene  quand 
des  circonstances  particulieres  ou  les  travaux  des  hommes  les  en  ont  momentanement 
ecartees 
The  data  upon  which  M.  Gieaed  founds  his  conclusion  appear  to  me  to  be  far  too 
loose  and  indeterminate  in  their  nature,  and  insufficient  in  number,  to  warrant  the 
establishment  of  what  may  be  termed  a law  of  increase.  Some  observations  are  stated 
to  have  been  made  at  Thebes,  Siout,  Heliopolis,  and  some  other  places,  with  the  view 
of  testing  the  accuracy  of  this  rate  of  secular  increase,  by  digging  into  the  alluvial  soil 
at  the  foot  of  ancient  monuments,  applying  to  remote  antecedent  periods  the  rate  which 
had  been  founded  upon  observations  which  had  reference  only  to  comparatively  recent 
times ; but  in  none  of  those  cases  was  any  definite  result  obtained  confirmatoiy  of  the 
assumed  rate. 
As  regards  the  observations  at  the  Nilometer  of  Elephantina,  they  are  accompanied 
by  some  sources  of  uncertainty.  In  the  more  than  2000  years  between  its  erectionf 
and  the  time  of  M.  Gieaed’s  observations,  it  is  far  from  improbable  that  the  foundation 
of  the  building  may  have  sunk,  an  occurrence  by  no  means  rare,  and  which,  it  is  believed, 
has  happened  to  the  Nilometer  of  Rhoda.  It  is  assumed  only  that  the  figure  24  marked 
the  highest  inundations  at  the  time  of  the  formation  of  the  scale ; it  is  assumed  that  the 
mark  and  inscription  had  been  made  by  the  Roman  garrison  mth  the  intention  of 
recording  the  highest  flood  at  that  period.  The  mark  on  the  external  wall  is  not  a per- 
fectly reliable  proof  of  the  height  to  which  the  inundations  in  reepnt  times  may  have 
reached,  as  it  may  have  been  caused,  so  near  the  cataract,  by  some  temporaiy  and  pimely 
local  accumulation  of  the  water.  After  the  river  has  attained  its  stationary  salibe  level, 
it  sometimes  continues  to  rise  several  inches  higher,  on  account  of  occasional  and  sudden 
torrents  falling  into  the  Nile  valley  by  some  of  the  numerous  side  rapines,  which  bring 
down  the  rain-water  from  the  Arabian  or  Libyan  Hills ; rain-clouds  mth  thimder  and 
lightning  frequently  cross  the  valley,  coming  generally  from  the  west,  and  the  rain  falls 
very  heavily. 
As  regards  the  Rhoda  Nilometer,  it  is  difficult  to  comprehend  how  there  should  have 
been  so  trifling  a difference  between  the  relative  proportions  of  secular  increase  at  Ele- 
phantina and  Rhoda,  viz.  0T32  metre  and  0T20  metre,  from  which  M.  Gieaed  makes 
the  mean  secular  rise  of  the  bed  of  the  river  0T26.  I have,  akeady  shorni  how,  Rom 
various  causes,  there  must  be  a progressive  diminution  in  the  amount  of  sediment  as  the 
* Loc.  cit.  p.  266. 
■)•  “ Quant  a la  construction  de  cet  edifice,  je  ne  crois  pas  qu’on  puisse  en  faire  remonter  la  date  au  dela 
les  Ptolemees.  Les  caracteres  numeriques  qui  distinguent  chaque  coudee  prouvent  qu’il  est  I’ouvrage  des 
Grecs.” — Gieaed,  Description  de  I’Egypte,  Antiq.  Memoires,  tome  i.  p.  11. 
