﻿MODERN" 
  ASTRONOMY 
  ABBOT 
  163 
  

  

  Although 
  hfe 
  on 
  other 
  planets 
  than 
  the 
  earth 
  is 
  not 
  positively 
  

   tiemonstrated, 
  there 
  are 
  two 
  others, 
  JNIars 
  and 
  Venus, 
  on 
  which 
  its 
  

   existence 
  is 
  not 
  out 
  of 
  the 
  question. 
  . 
  Yet 
  life 
  depends 
  upon 
  a 
  nice 
  

   adjustment 
  of 
  various 
  conditions. 
  There 
  is 
  no 
  chemical 
  element 
  

   except 
  carbon 
  which 
  combines 
  with 
  other 
  elements 
  in 
  that 
  infinite 
  

   variety 
  of 
  potent 
  forms 
  so 
  indispensable 
  to 
  the 
  mysterious 
  processes 
  

   of 
  life. 
  Flexibility, 
  too, 
  is 
  requisite, 
  so 
  that 
  liquids 
  rather 
  than 
  

   solids 
  must 
  have 
  a 
  considerable 
  part 
  in 
  living 
  creatures. 
  Of 
  all 
  

   liquids 
  water 
  is 
  the 
  most 
  important, 
  but 
  even 
  of 
  the 
  numerous 
  

   organic 
  carbon-built 
  liquids, 
  those 
  more 
  conducive 
  to 
  life 
  properties 
  

   solidify 
  as 
  water 
  does 
  at 
  about 
  zero 
  centigrade. 
  These 
  considerations 
  

   incline 
  us 
  to 
  think 
  that 
  planetary 
  temperatures 
  about 
  as 
  high 
  as 
  the 
  

   earth's 
  are 
  requisite 
  at 
  least 
  to 
  the 
  higher 
  forms 
  of 
  life. 
  

  

  It 
  has 
  recently 
  been 
  observed 
  that 
  the 
  illuminated 
  side 
  of 
  Mars 
  

   reaches 
  equatorial 
  temperatures 
  approximating 
  those 
  of 
  our 
  spring 
  

   days 
  in 
  Philadelphia. 
  Both 
  oxygen 
  and 
  water 
  vapor 
  have 
  been 
  

   demonstrated 
  in 
  the 
  atmosphere 
  of 
  Mars, 
  but 
  in 
  comparatively 
  mi- 
  

   nute 
  quantities. 
  Adams 
  and 
  St. 
  John 
  find 
  of 
  oxygen 
  15 
  and 
  of 
  water 
  

   vapor 
  5 
  per 
  cent 
  of 
  the 
  quantities 
  prevailing 
  in 
  our 
  atmosphere. 
  

   So 
  the 
  Martian 
  life^ 
  if 
  it 
  exists^ 
  'must 
  he 
  adapted 
  to 
  atmospheric 
  

   composition 
  ajjproximating 
  that 
  high 
  above 
  the 
  summit 
  of 
  Mount 
  

   Everest. 
  

  

  As 
  the 
  atmosphere 
  of 
  Mars 
  is 
  so 
  very 
  rare 
  and 
  dry, 
  it 
  is 
  unsuitable 
  

   to 
  retain 
  heat 
  at 
  night. 
  Computation 
  and 
  observation 
  unite 
  in 
  

   estimating 
  the 
  midnight 
  temperatures 
  of 
  equatorial 
  Mars 
  as 
  of 
  the 
  

   order 
  of 
  —40° 
  C. 
  These 
  frigid 
  night 
  temperatures, 
  combined 
  with 
  

   the 
  rare 
  and 
  dry 
  atmosphere, 
  would 
  seem 
  to 
  exclude 
  from 
  Mars 
  

   the 
  higher 
  types 
  of 
  life, 
  such 
  as 
  we 
  know, 
  but 
  might 
  permit 
  certain 
  

   arctic 
  types 
  to 
  exist. 
  Indeed, 
  the 
  seasonal 
  changes 
  of 
  color 
  which 
  

   are 
  observed, 
  seem 
  to 
  many 
  to 
  be 
  satisfactory 
  evidence 
  of 
  vegetation 
  

   on 
  Mars. 
  

  

  Upon 
  Venus 
  there 
  is 
  no 
  defect 
  of 
  temperature, 
  or 
  of 
  the 
  uniformity 
  

   of 
  it. 
  With 
  greater 
  nearness 
  to 
  the 
  sun 
  but 
  higher 
  reflecting 
  power, 
  

   the 
  solar 
  radiation 
  available 
  to 
  warm 
  Venus 
  is 
  about 
  one 
  and 
  four- 
  

   tenths 
  times 
  as 
  intense 
  as 
  that 
  which 
  warms 
  the 
  earth. 
  Accordingly, 
  

   temperatures 
  approximating 
  those 
  of 
  our 
  Tropics 
  should 
  prevail 
  in 
  

   latitudes 
  well 
  toward 
  this 
  planet's 
  poles. 
  An 
  abundant 
  atmosphere 
  is 
  

   present. 
  The 
  reflecting 
  power 
  approximates 
  that 
  of 
  a 
  completely 
  

   cloudy 
  earth, 
  so 
  that 
  it 
  would 
  be 
  reasonable 
  to 
  conceive 
  of 
  clouds 
  of 
  

   water, 
  completely 
  hiding 
  the 
  planet 
  surface 
  at 
  all 
  times. 
  

  

  The 
  spectroscope, 
  however, 
  does 
  not 
  confirm 
  this. 
  Neither 
  water- 
  

   vapor 
  nor 
  oxygen 
  can 
  certainly 
  be 
  discerned 
  thereby. 
  Yet 
  it 
  seems 
  

   incredible 
  that 
  we 
  sec 
  the 
  surface 
  of 
  this 
  planet, 
  whose 
  bulk 
  must 
  be 
  

   solidified 
  since 
  its 
  density 
  is 
  nearly 
  the 
  same 
  as 
  the 
  earth's. 
  For 
  if 
  

  

  