﻿THE 
  

  

  AMERICAN 
  JOURNAL 
  OF 
  SCIENCE 
  

  

  [FOURTH 
  SERIES.] 
  

  

  Art. 
  XXYI. 
  — 
  Exjjlosive 
  effect 
  of 
  JElectriaal 
  Discharges 
  ; 
  by. 
  

   John 
  Trowbridge, 
  T. 
  C. 
  McKay 
  and 
  J. 
  C. 
  Howe. 
  With 
  

   Plate 
  Y. 
  

  

  Since 
  the 
  time 
  of 
  Franklin 
  the 
  subject 
  of 
  the 
  explosive 
  

   effect 
  of 
  electrical 
  discharges 
  has 
  been 
  studied 
  by 
  numerous 
  

   investigators, 
  and 
  an 
  extended 
  bibliography 
  of 
  their 
  work 
  is 
  

   contained 
  in 
  Wiedemann's 
  " 
  Galvanismus 
  und 
  Electromag- 
  

   netismus." 
  

  

  The 
  resources 
  of 
  the 
  Jeiferson 
  Physical 
  Laboratory 
  permit- 
  

   ting 
  the 
  study 
  of 
  this 
  phenomenon 
  over 
  greater 
  range 
  than 
  has 
  

   hitherto 
  been 
  possible, 
  we 
  have 
  undertaken 
  the 
  work 
  in 
  the 
  

   hope 
  of 
  further 
  elucidating 
  the 
  subject. 
  The 
  laboratory 
  pos- 
  

   sesses 
  two 
  high 
  tension 
  transformers 
  or 
  Plants 
  rheostatic 
  

   machines 
  — 
  one 
  giving 
  discharges 
  of 
  125 
  centimeters 
  in 
  length, 
  

   and 
  one 
  yielding 
  sparks 
  180 
  to 
  200 
  centimeters 
  in 
  length. 
  

   These 
  transformers 
  are 
  connected 
  to 
  a 
  battery 
  of 
  ten 
  thousand 
  

   cells, 
  and 
  can 
  yield 
  voltages 
  from 
  twenty 
  thousand 
  to 
  three 
  

   million. 
  Various 
  methods 
  of 
  measurement 
  were 
  tried. 
  On 
  

   account 
  of 
  the 
  great 
  tension 
  all 
  galvanometric 
  and 
  electro- 
  

   metric 
  means 
  had 
  to 
  be 
  abandoned 
  ; 
  and 
  what 
  is 
  known 
  as 
  the 
  

   electric 
  thermometer 
  was 
  finally 
  adopted. 
  This 
  consists, 
  as 
  is 
  

   well 
  known, 
  of 
  a 
  hermetically 
  closed 
  glass 
  tube, 
  provided 
  with 
  

   a 
  manometer 
  gauge. 
  The 
  electrical 
  discharge 
  passes 
  through 
  

   the 
  tube 
  by 
  means 
  of 
  a 
  fine 
  wire, 
  or 
  by 
  a 
  spark 
  gap. 
  The 
  

   term 
  electrical 
  thermometer 
  is 
  a 
  misleading 
  one 
  ; 
  for 
  as 
  we 
  

   shall 
  show, 
  the 
  quick 
  movement 
  of 
  the 
  manometer 
  gauge 
  is 
  not 
  

   due 
  to 
  heat. 
  

  

  At 
  first 
  we 
  passed 
  the 
  discharges 
  through 
  very 
  fine 
  wire. 
  

   The 
  gauge, 
  which 
  consisted 
  of 
  a 
  bent 
  glass 
  tube 
  containing 
  an 
  

  

  A.M. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Yol. 
  VIII, 
  No. 
  46.— 
  October, 
  1899. 
  

   17 
  

  

  