ON  THE  PEAK  OE  TENEEIEFE. 
485 
few  others  also  by  slips  or  bad  drawing,  we  must  take  the  whole  as  he  has  given  it 
imphcitly,  or  reject  it  entirely. 
If  astronomical  dra'udng  is  to  take  a similar  trustworthy  and  trusted  place  to  numerical 
observation,  in  its  own  branch  of  subjects,  we  must  in  the  first  place  with  every  man’s 
work,  eliminate  errors  in  drawing  and  imperfections  of  the  means  and  medium  em- 
ployed. How  easily  much  of  this  may  often  be  accomphshed  by  two  drawings,  may  be 
well  seen  in  some  of  the  photographs  in  the  book  of  illustrations ; for  having  been  taken 
with  stereoscopic  intentions,  they  are  all  double.  Hence,  is  there  some  doubtful  mark  in 
one  ? we  have  only  to  look  to  the  other ; and  if  the  mark  was  in  the  scene  itself  in  nature, 
it  will  likewise  appear  in  the  second  rfew  as  well ; but  not  so  if  it  were  merely  a fault 
or  imperfection  m the  surface  of  the  plate. 
After  this  first  step  has  been  accomplished,  comes  the  more  difficult  affair  of  elimi- 
nating the  personal  and  instrumental  equation,  from  which  source  of  error  no  object  in 
the  heavens  has  suffered  so  much  as  our  present  subject,  Saturn.  Thus  the  elongation 
of  Saturn’s  rings  in  old  drawings,  not  confirmed  by  micrometrical  observation,  may  be 
mainly,  if  not  entirely,  attributable  to  the  earlier  observers — in  their  desire  to  intensify 
their  discovery,  and  to  prove  that  they  had  a clear  perception  of  the  sky  intervening 
between  the  inner  border  of  the  ring  and  the  ball — having  pulled  out  the  ends  of  the 
ring  much  further  than  they  were  justified ; just  as  a sketcher  invariably  increases  the 
steepness  of  all  his  mountain  slopes.  Again,  up  to  even  the  last  few  years,  the  published 
drawings  of  Saturn,  with  a few  bright  exceptions,  as  the  Heeschels’,  have  exhibited  such 
en’oneous  ellipses — that  if  the  shape  and  dimensions  of  his  rings  and  their  divisions 
were  to  be  computed  on  such  testimony — they  would  be  found  to  be  endued  with  more 
anomalous  derfations  from  their  nearly  circular  form,  than  any  one  has  ever  ventured  to 
attribute  to  them,  and  which  the  artists  themselves  had  never  intended. 
To  improve  this  state  of  things,  Mr.  He  la  Eue  has  lately  not  only  given  us  such 
admirable  drawings,  as  stamp  him  as  the  artist  par  excellence  of  Saturn,  but  he  has,  by 
his  extensively  distributed  diagrams,  produced  a sudden  and  general  improvement  in  all 
the  current  delineations  of  the  planet. 
My  drawing,  I find,  approximates  pretty  closely  to  his,  but  in  some  of  the  smaller 
features  inclines  more  to  Captain  Jacob’s  rfew',  as  thus, — 1st,  the  principal  division  is  not 
perfectly  black,  but  of  the  tint  of  the  dark  ring ; 2nd,  the  fine  division  is  not  accom- 
panied by  a bright  band ; 3rd,  the  dark  parts  of  the  ball  do  not  take  accurately  defined 
zones ; and  4th,  the  shadow  of  the  ball  on  the  ring  is  remarkably  sharply  defined. 
(3.)  Eclipse  red  prominences. 
Under  the  date  of  September  the  9th,  in  vol.  i.,  or  the  Astronomical  Journal,  will  be 
found  particulars  of  what  may  be  an  observation  of  one  of  the  eclipse  red  prominences ; 
but  as  the  view'  of  it  was  uncertain  in  the  extreme,  and  all  the  other  attempts  that  were 
made  were  entirely  unsuccessful,  I think  it  better  to  allow  that  this  department  of  our 
work  was  a failure, — a failure  not  from  any  deficiency  of  the  instruments,  though  these 
