﻿384 
  ON 
  THE 
  CAUSES 
  OF 
  THE 
  TORNADO, 
  OR 
  WATER 
  SPOUT. 
  

  

  All 
  the 
  information 
  respecting 
  tornadoes 
  afforded 
  by 
  Despretz 
  is 
  

   comprised 
  in 
  the 
  following 
  paragraphs, 
  which 
  I 
  quote 
  in 
  his 
  own 
  

   words. 
  

  

  " 
  Trombe. 
  La 
  trombe 
  se 
  montre 
  en 
  mer 
  et 
  sur 
  la 
  terre 
  ; 
  tantot 
  elle 
  

   semble 
  sortir 
  du 
  sein 
  de 
  la 
  mer, 
  et 
  s'eleve 
  jusqu'aux 
  nuages; 
  tantot 
  

   elle 
  descend 
  des 
  nuages 
  jusqu'a 
  terre. 
  

  

  "C'est 
  une 
  colonne 
  d'eau 
  conique 
  qui 
  tourne 
  sur 
  elle-memeavec 
  une 
  

   grande 
  vitesse; 
  elle 
  a 
  quelquefois 
  jusqu'a 
  plus 
  de 
  deux 
  cents 
  metres 
  de 
  

   base. 
  Elle 
  est 
  tres-commune 
  entre 
  les 
  tropiques 
  : 
  les 
  navigateurs 
  passent 
  

   rarement 
  pres 
  des 
  cotes 
  de 
  Guinee 
  sans 
  en 
  apercevoir 
  plusieurs. 
  

  

  "Les 
  trombes 
  produisent 
  des 
  effets 
  terribles 
  ; 
  elles 
  deracinent 
  les 
  ar- 
  

   bres, 
  renversent 
  les 
  faibles 
  habitations, 
  soulevent 
  les 
  voitures, 
  etc. 
  

  

  "On 
  peut 
  se 
  faire 
  une 
  idee 
  des 
  trombes 
  paries 
  tourbillons 
  de 
  pouis- 
  

   siere 
  qui 
  se 
  forment 
  tout 
  a-coup, 
  en 
  ete, 
  sur 
  les 
  routes, 
  et 
  qui 
  tournent 
  

   sur 
  eux-memes 
  avec 
  une 
  grande 
  rapidite." 
  — 
  Traite 
  Elementaire 
  de 
  

   Physique, 
  paragraph 
  656, 
  page 
  828, 
  par 
  C. 
  Despretz. 
  

  

  In 
  Nicholson's 
  Journal, 
  quarto 
  series, 
  London 
  1797, 
  vol. 
  1, 
  page 
  

   583, 
  there 
  is 
  an 
  interesting 
  account 
  of 
  some 
  tornadoes 
  seen 
  from 
  Nice, 
  

   illustrated 
  by 
  engravings, 
  by 
  M. 
  Michaud, 
  who 
  appears 
  to 
  consider 
  

   them 
  as 
  the 
  effect 
  of 
  electricity, 
  and 
  infers 
  that 
  he 
  could 
  produce 
  the 
  

   phenomenon 
  in 
  miniature 
  by 
  the 
  aid 
  of 
  a 
  machine, 
  as 
  thunder 
  and 
  

   lightning 
  are 
  by 
  the 
  same 
  means 
  illustrated. 
  This 
  I 
  have 
  found 
  to 
  be 
  

   erroneous, 
  as 
  far 
  as 
  my 
  experience 
  goes, 
  and 
  from 
  a 
  cause 
  which 
  is, 
  

   agreeably 
  to 
  my 
  hypothesis, 
  quite 
  evident. 
  I 
  mean 
  the 
  absence 
  of 
  the 
  

   co-operating 
  influence 
  of 
  the 
  air 
  when 
  emancipated 
  by 
  electric 
  attrac- 
  

   tion 
  from 
  the 
  confinement 
  arising 
  from 
  its 
  own 
  weight. 
  

  

  The 
  theoretic 
  remarks 
  of 
  Michaud 
  are 
  very 
  brief, 
  and, 
  to 
  me, 
  scarcely 
  

   intelligible, 
  as 
  he 
  does 
  not 
  inform 
  us 
  in 
  what 
  way 
  he 
  supposes 
  the 
  

   electric 
  fluid 
  to 
  operate. 
  

  

  I 
  have 
  understood, 
  since 
  I 
  conceived 
  my 
  hypothesis, 
  that 
  Beccaria 
  as- 
  

   cribed 
  water 
  spouts 
  to 
  electricity, 
  but 
  I 
  have 
  not 
  had 
  the 
  advantage 
  of 
  

   learning 
  by 
  what 
  reasoning 
  he 
  justified 
  his 
  inferences. 
  However, 
  should 
  

   it 
  appear 
  that 
  I 
  have 
  made, 
  through 
  the 
  want 
  of 
  information, 
  any 
  undue 
  

   claim 
  to 
  priority, 
  I 
  shall 
  cheerfully 
  do 
  justice 
  to 
  any 
  philosopher 
  whose 
  

   speculations 
  I 
  may 
  have 
  overlooked. 
  

  

  