478  Intelligence  and  Miscellaneous  Articles. 
feet,   will  give  us  the  number  of  thermal  units  generated  every 
second  of  time. 
Now  it  has  been  found  by  observation  that  the  heat  emitted  by  the 
sun  to  the  earth  is  sufficient  to  melt  a  sheet  of  ice  whose  thickness 
is  0*01093  inch  when  exposed  perpendicularly  to  the  solar  rays  for 
one  minute  (Sir  John  Herschel,  '  Meteorology '),   due    allowance 
having  been  made  for  the  heat  absorbed  by  the  atmosphere ;  and 
therefore  in  one  second  a  sheet  of  ice  whose  thickness  is  0*0000152 
foot  will  thus  be  melted ;  so  that  if  a  be  the  mean  distance  of  the 
earth  from  the  sun  expressed  in  feet,  a  spherical  shell  of  ice,  whose 
radius  is  a  and  thickness  0*0000152  foot,  will  be  the  volume  of  ice 
in  cubic  feet  melted  every  second  by  the  whole  of  the  radiant  solar 
heat.       But   one  pound  of  ice  has  a  volume  equal  to   (0*2584)3 
,.    *         ,       *       4;ra2x  0*0000152      .„  _      ,  .  _        _  ,     . 
cubic  foot,  therefore  — ,n  ^„„,N, will  be  the  weight  of  the  ice 
(0*2584)3 
in  pounds  thus  melted. 
Again,  in  order  to  melt  one  pound  of  ice,  79*25  thermal  units  are 
required ;  and  thus  the  whole  solar  heat  evolved  in  one  second  of 
,       4yra2x  79*25x0*0000152   ,  ,       . 
time  is  equal  to (o-o^R4\s thermal  units. 
Now,  by  equating  the  heat  generated  to  the  heat  evolved  in  one 
second,  we  get 
47rz0r03  x  2431  _  47ra2  x  79*29  x  0*0000152 
5x1390  (0*2584)3 
and  the  contraction  z0  is  therefore  only  0*000004079  foot  in  one 
second,  or  129  feet  per  annum ;  and,  as  we  have  already  said,  ages 
must  elapse  before  the  effect  of  this  contraction  can  become  visible 
to  us,  whether  we  compare  direct  measures  of  the  solar  disk  or  ob- 
served periods  of  axial  rotation. 
The  contraction,  therefore,  is  so  small  that  as  much  allowance  can 
be  made  for  the  assumptions  introduced  above  as  may  be  thought 
necessary,  without  altering  our  general  conclusion  in  the  slightest 
degree — namely,  that  the  source  of  the  solar  heat  and  light  is  con- 
nected with  the  mechanical  theory  of  heat  by  means  of  the  contrac- 
tion of  the  composing  mass. 
The  application  of  this  theory  to  other  bodies  is  almost  without 
limit ;  the  earth  has  contracted,  and  has  stored  up  a  corresponding 
amount  of  heat  in  the  non-conducting  rocks  and  soils  ;  the  stars,  by 
their  intrinsic  brilliancy,  indicate  the  operation  of  the  force  of  gra- 
vity upon  contracting  matter;  the  nebulas  afford  examples  of  the 
commencement  of  this  operation  ;  and  periodical  variations  in  light 
now  become  perturbations,  the  effect  of  disturbing  masses  in  motion, 
producing  endless  changes  subject  to  the  great  principle  known  as 
the  conservation  of  energy. — Monthly  Notices  of  the  Royal  Astrono- 
mical Society,  April  12,  1872. 
NEW   SENSITIVE    SINGING-FLAME.       BY  W.  E.  GEYER,  OF    THE 
STEVENS  INSTITUTE  OF  TECHNOLOGY. 
Philip  Barry  has  recently  described  *  a  very  sensitive  flame  pro- 
*  '  Nature,'  vol.  v.  30,  Nov.  2,  1871.     [This  form  of  apparatus  would  seem 
