One  of  the  brothers,  Robert  (by  whom  the  Balloon  was  con-
structed), took  part  in  the  ascent.
The  Balloon  ascended  from  the  Tuileries  and  reached  a  height
of  about  2,000  feet.  It  descended  two  hours  later  at  Nesle,  27  miles
from  Paris.
Robert  left  the  car,  and  Charles  made  a  second  ascent  alone.
(See  Illustration.)  Thus  greatly  lightened,  the  Balloon  rose  rapidly
to  a  height  of  two  miles,  and  remained  in  the  air  for  half  an  hour,
eventually  descending  three  miles  away.
All  the  accessories  of  the  Balloon  in  use  at  the  present  time  are
more  or  less  due  to  Charles,  who  invented  the  valve  at  the  top  and
suspended  the  car  from  a  hoop,  which  was  itself  attached  to  the
Ballpon  by  netting.
^  With  regard  to  the  use  of  hydrogen  gas,  Henry  Cavendish  in
1766  demonstrated  that  it  was  seven  times  lighter  than  air,  and
Dr.  Joseph  Black,  considered  that  a  thin  bag  filled  with  the  gas  would
rise  to  the  ceiling  of  a  room.
A  similar  idea  occurred  to  Tiberius  Cavallo,  and  the  year
before  the  invention  of  the  Brothers  Montgolfier  he  had
succeeded  in  elevating  soap  bubbles  by  inflating  them  with  hydro-
gen gas.
Researches  on  the  use  of  gas  for  inflating  Balloons  appear  to
have  been  carried  out  at  Philadelphia  almost  simultaneously  with  the
experiments  of  the  Brothers  Montgolfier;  therefore,  when  the  news
of  the  latter  reached  America,  Dr.  Rittenhouse  and  F.  Hopkinson,
members  of  the  Philosophical  Society  of  Philadelphia,  constructed
a  machine  consisting  of  47  small  hydrogen  gas  Balloons  attached  to
a  car  or  cage.
After  several  preliminary  captive  experiments,  in  which  certain

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No.  45.  CiiARLiis  (scf  Catalogue).
