219 
Bulletin  physico -mathématique 
220 
JY  = C — ( Cl  -f  C2  -f-  C3 . . . -f-  C62)  -f-  (É’i  . 2 -f  C2 
“P  (^T  • 2-  3-4  “P  ~b  f 59  . 60  • 61  • 62) 
Beweis.  Man  wähle  einige  Zwischenfelder  beliebig 
ans  und  untersuche  wie  oft  die  Anzahl  ( z.)  der  Ueber- 
gänge  , bei  welchen  alle  diese  und  nur  diese  Zwischen- 
felder leer  bleiben  , in  vorstehender  Formel  gesetzt  ist. 
Sie  ist  in  C , der  Anzahl  aller  möglichen  Uebergänge  ? 
einmal  gesetzt  ; in  -f-  C2  -f-  . . -f-  C62)  emal , wrenn 
v die  Anzahl  der  ausgewählten  Felder  ist.  Sind  nämlich 
1,  2,  3 . . v die  Zeiger  dieser  Felder,  so  ist  die  Zahl  2 
in  jeder  der  Zahlen  Cv  C2  . . .C  einmal,  in  den  übri- 
gen (7,  , x . . . C62  gar  nicht  gesetzt.  In  jeder  der  Zah- 
len Cx  . 2,  Cy  . 3 . . . Cv . j , in  welchen  alle  Verdindun- 
•3 4“  ^61  • 6a)  (Ç\  • 2 • 3 • • • "f*  ^ 60  ■ 61  • 62) 
"É ^1  • 2 ■ 3 ■ 4 • • • • 62* 
gen  von  zweien  der  Zeiger  1,  2,  3 . . v Vorkommen  , ist 
z einmal  gesetzt,  also  in  (Ui  . 2 -f  Ui  . . -f  . . . -j-  C61  . 62) 
V ,v  — i 
— 2 — mal  » da  es  in  den  übrigen  Zahlen  dieser  Reihe 
gar  nicht  gesetzt  ist.  Auf  diese  Weise  fortschliessend 
findet  man  z in  der  Formel  für  N gesetzt 
e.e  — 1 
(1  - iy  = 0 mal  : 
1 
^ + .... 
folglich  wird  in  dieser  Formel  nur  die  Anzahl  der  kein 
Feld  ausschliessenden  Uebergänge  von  yl  auf  B einmal 
gesetzt  5 w.  z.  b.  w. 
OOnnESFÖXTDAlTSE. 
î . Lettre  de  Sir  Pi 0 D . MURCHISON  a 
M.  FUSS.  (Lu  le  30  avril  18V7). 
Loudon  April  IS,  1847. 
S 
ir. 
Anxious  not  to  appear  wanting  in  my  duty  to  the 
illustrious  Academy  of  Sciences  of  St.  Petersburg  which 
has  so  honoured  me,  I have  requested  my  friend  and 
coadjutor  Colonel  Helmersen  to  oiler  to  my  associates 
my  last  published  Memoirs  on  the  geology  of  the  Norlh 
of  Europe,  i.  e.  non  the  drift  (terrain  de  transport)  and 
erratic  blocks  of  Sweden»  and  «on  the  Silurian  Rocks» 
of  that  country. 
Permit  me  to  state  that  both  these  Memoirs  are  in- 
timately connected  with  the  geology  of  Russia.  In  the 
first  of  them  I have  endeavoured  to  shew,  that  the 
rolled  gravel  or  drift  has  unquestionably  resulted  from  a 
cause , distinct  from  that  which  transported  the  great 
angular  and  sub-angular  blocks.  Previous  authors  (in- 
cluding myself)  have  not  indicated  that  the  latter  mate- 
rials are  superposed  to  the  former  ; and  I have  inferred 
that  the  worn , striated  and  polished  surfaces  of  the 
hard  rocks  of  Scandinavia  and  of  Russia,  have  been 
produced  by  aqueous  debacles  which  hurled  on  the 
gravel  and  sand  of  the  Asar,  whilst  floating  ice-bergs 
alone  could  have  carried  the  great  angular  and  over- 
lying  blocks  to  their  present  positions.  I hope  the  Aca- 
demy will  entertain  writh  indulgence  the  . view  1 have 
taken  of  the  application  to  ancient  operations  of  ice, 
of  the  existing  natural  causes,  first  made  known  to  me 
on  the  Dwina  of  Archangel  and  extended  by  myself  to 
the  angular  block  ridges  at  different  levels  on  the  shores 
of  the  Lake  Onega  (see:  Russia  and  the  Ural  Mountains). 
I have  now  sought  still  further  to  extend  this  reasoning 
from  existing  causes,  in  explanation  of  the  vast  assembla- 
ges of  angular  blocks  in  situ  in  Dalecarlia  — phenomena 
which  are  totally  irreconcileahle  with  any  of  the  forms 
of  terrestrial  glacial  action  insisted  upon  by  the  Alpine 
naturalists. 
The  memoir  on  the  Silurian  Rocks  of  Sweden  is  also 
to  be  considered  as  an  addition  to  the  general  work  on 
Russia  by  my  friends,  M.  de  Verneuil  and  Count  v. 
Keyserling  and  myself,  which  I wdll  leave  to  my 
colleague  Colonel  Helmersen  to  explain. 
Permit  me  now  to  offer  a direct  contribution  to  the 
advancement  of  Russian  science,  in  a new  edition  of  the 
Map  of  «Russia  and  the  Ural  mountains»  with  the  ad- 
jacent tracts.  The  chief  improvement  in  this  Map  re- 
fers to  Turkey , Wallachia  and  Moldavia,  countries  which 
neither  myself  nor  my  coadjutors  had  visited.  Having 
j heard , through  Count  v.  Keyserling,  that  several  in- 
! accuracies  existed  in  our  map  in  respect  to  those  regions, 
! I requested  M.  Boue,  their  able  and  indefatigable  explo- 
! rer,  to  correct  these  defects;  and  as  he  has  kindly  done 
