ON  THE  PEAK  OF  TENEEIFFE. 
483 
Journal;  and  the  only  remark  that  need  be  made  here,  is,  in  connexion  with  the 
astonishing  visibility  of  the  companion  of  Antares,  which  escaped  Steuve,  with  an  instru- 
ment wheremth  he  discovered  the  duplicity  of  B and  C Andromedge,  and  so  many  other 
ditficult  tests.  When  we  bear  in  mind  the  great  altitude  of  these  latter  stars  in  Russia, 
and  the  very  low  altitude  of  Antares  there,  the  case  may  be  taken  as  a strong  illustra- 
tion of  the  importance  of  eliminating  atmosphere  from  observation  in  every  possible 
way ; not  only  by  chmbing  up  a mountain,  but  by  each  observatory  confining  itself  to 
the  objects  in  the  neighbourhood  of  its  own  zenith. 
(2.)  Moon  and  Planets. 
At  Guajara,  with  the  Sheepshanks  telescope,  there  were  many  tempting  opportunities 
of  delineating  parts  of  the  moon’s  surface ; but  the  small  power  of  the  telescope  pre- 
vented such  work  being  as  good  disposal  of  my  time,  as  many  other  observations  that 
equally  claimed  attention.  Moreover  there  was  so  remarkable  a tendency  of  bright 
points  of  the  lunar  craters  to  form  stellar  disks  and  rings,  that  I was  additionally 
induced  to  defer  anything  in  this  hne,  until  the  Pattinson  equatorial  with  the  trans- 
parent glass  reflector-eyepiece  should  be  erected. 
This  instrument  was  established  at  the  Alta  Vista  in  September,  but  the  last  quarter, 
which  was  to  have  been  the  lunar  observing  period,  was  interfered  with  by  the  premature 
setting  in  of  autumn.  In  the  first  quarter  of  that  month  we  had  several  opportunities, 
but  not  many  or  good  ones,  as  the  moon  was  then  very  low  in  southern  declination,  and 
the  lava  ridges  rose  high  to  the  west  of  us. 
Those  few  views,  however,  with  magnifying  powers  from  160  to  660,  made  a most  vivid 
impression  on  the  minds  of  all  at  the  station.  There  have  been  doubts  expressed  by 
some  geologists,  as  to  whether  the  circular  caVties  in  the  moon  are  craters ; had  they 
enjoyed  these  opportunities  at  the  Alta  Vista,  they  would  have  renounced  such  doubts, 
so  many  and  so  striking  were  the  analogies  between  the  craters  of  Teneriffe  and  those 
we  saw  in  the  moon.  Among  the  most  characteristic  perhaps  of  the  resemblances, 
is  the  greater  steepness  of  the  inner  over  the  outer  wall  of  every  cavity  or  ring-shaped 
mountain ; again,  the  precipitous  ledges,  and  often  the  conchoidal  bays  and  recesses  of 
the  inner  wall ; and  the  generally  level  floors  of  the  cavities,  with  here  and  there  a peak 
raised  upon,  or  a little  cup-shaped  ca\ity  established  in  them. 
But  the  telescope  showed  over  and  above  those  well-known  features,  such  an  in- 
finity of  detail,  that  though  I tried  once  or  twice  (see  the  view  of  Autolycus  in  Plate 
XXXIV.),  I found  it  quite  impossible  to  make  a proper  drawing  of  any  notable  part, 
in  the  contracted  space  of  time  between  darkness  and  the  moon  going  behind  the  lava 
ridge.  Half  a night  would  have  been  short  time  enough.  In  this  department  there  is 
indeed  an  immensity  to  accomplish ; the  clear  air  of  the  Peak  would  be  most  favourable ; 
and  the  opportunity  that  the  astronomer  would  have,  probably  for  the  first  time  in  his 
life,  for  ascertaining  the  distinctive  forms  of  terrestrial  craters  from  eight  miles  in 
diameter  to  300  feet,  would  enable  him  to  appreciate  better  the  minute  revelations  of 
