Intelligence  and  Miscellaneous  Articles.  79 
a  corresponding  in-rush :  and  it  seems  far  from  impossible  that  the 
mysterious  coronal  streamers,  if  they  turn  out  to  be  truly  solar,  as 
now  seems  likely,  may  have  their  origin  and  find  their  explanation 
in  such  events. 
The  same  afternoon  a  portion  of  the  chromosphere  on  the  oppo- 
site (western)  limb  of  the  sun  was  for  several  hours  in  a  state  of 
unusual  brilliance  and  excitement,  and  showed  in  the  spectrum  more 
than  1 20  bright  lines,  whose  position  was  determined  and  catalogued, 
— all  that  I  had  ever  seen  before,  and  some  15  or  20  besides. 
Whether  the  fine  aurora  borealis  which  succeeded  in  the  evening 
was  really  the  earth's  response  to  this  magnificent  outburst  of  the 
sun  is  perhaps  uncertain  ;  but  the  coincidence  is  at  least  suggestive, 
and  may  easily  become  something  more  if,  as  I  somewhat  confidently 
expect  to  learn,  the  Greenwich  magnetic  record  indicates  a  disturb- 
ance precisely  simultaneous  with  the  solar  explosion. — Silliman's 
American  Journal,  Dec.  1871. 
Dartmouth  College,  U.S.,  September  1871. 
ON  THE  TRANSVERSE  VIBRATIONS  OF  WIRES  AND  THIN  PLATES. 
BY  M.  E.  GRIPON. 
Wires  and  thin  plates  of  metal,  fixed  to  the  branch  of  a  diapason 
and  having  one  extremity  free,  vibrate,  by  communication,  after  the 
manner  of  rods  and  in  unison  with  the  diapason.  The  same  as  in 
Melde's  experiments  on  stretched  wires,  on  these  little  rods  a  certain 
number  of  loops  are  distinguished  separated  by  nodes.  The  equa- 
tions of  the  motion  of  the  wire,  regarded  either  as  a  string  or  as  a 
rod,  can  be  found  by  analysis.  The  results  of  the  calculation  are 
completely  verified  by  experiment. 
The  number  of  the  nodes  varies  with  the  length  of  the  rod ;  the 
distances  from  each  of  these  nodes  to  the  free  extremity  are  inde- 
pendent of  its  length.  The  relative  distances  of  the  nodes  are  exactly 
the  same  as  on  a  rod  fixed  at  one  extremity  and  free  at  the  other, 
with  one  exception — that  the  extremity  fixed  to  the  diapason  is  not 
always  a  node,  but  its  distance  from  the  nearest  node  varies  with  the 
length.  In  general  the  rod  does  not  vibrate,  or  vibrates  irregularly, 
when  the  node  ought,  theoretically,  to  be  formed  at  the  point  of 
attachment  of  the  rod  to  the  diapason. 
The  normal  distances  of  two  consecutive  nodes  are  inversely  pro- 
portional to  the  square  roots  of  the  numbers  of  vibrations  of  the  dia- 
pasons employed,  and  cceteris  paribus  proportional  to  the  square  roots 
of  the  thicknesses  of  the  rods.  The  accord  of  theory  with  experi- 
ment is  so  far  complete  that  the  velocity  of  sound  in  the  rod  used 
can  be  determined  by  measuring  the  normal  distance  between  two 
consecutive  nodes,  the  thickness  of  the  rod,  and  ascertaining  the 
number  of  the  vibrations  of  the  diapason. 
This  very  simple  method  leads,  for  the  usual  metals,  to  the  num- 
bers already  found  by  Wertheim  and  Masson.  It  is  perfectly  appli- 
cable to  the  case  in  which  we  have  to  do  with  very  flexible  sub- 
stances, such  as  paper ;  in  these  cases  the  usual  methods  are  defective. 
