﻿Analogy 
  between 
  the 
  Catlwdic 
  Rays 
  and 
  those 
  of 
  Rontgen. 
  163 
  

  

  There 
  is 
  a 
  kind 
  of 
  tradition 
  that 
  paraffin-wax 
  is 
  a 
  perfect 
  

   safeguard 
  against 
  moisture 
  ; 
  as 
  a 
  matter 
  of 
  fact 
  it 
  is 
  highly 
  

   absorbent. 
  The 
  wax 
  on 
  the 
  bobbins 
  returned 
  from 
  the 
  tropics 
  

   is 
  completely 
  choked 
  with 
  moisture. 
  Shellac, 
  or 
  the 
  old- 
  

   fashioned 
  sealing-wax 
  varnish, 
  resists 
  much 
  better. 
  There 
  is 
  

   no 
  evidence 
  to 
  show 
  that 
  ebonite 
  is 
  harmful 
  to 
  german-silver 
  

   or 
  platinoid, 
  but 
  it 
  may 
  be 
  well 
  to 
  keep 
  the 
  metal 
  out 
  of 
  

   actual 
  contact 
  with 
  ebonite. 
  

  

  Can 
  metallurgists 
  tell 
  us 
  the 
  difference, 
  in 
  constitution 
  

   and 
  structure, 
  between 
  a 
  german-silver 
  wire 
  that 
  decays 
  in 
  

   four 
  weeks, 
  and 
  another 
  that 
  under 
  similar 
  conditions 
  never 
  

   fails 
  ? 
  Or, 
  what 
  is 
  even 
  more 
  important, 
  can 
  they 
  make 
  us 
  

   platinoid 
  that 
  shall 
  never 
  fail 
  ? 
  If 
  they 
  cannot, 
  it 
  becomes 
  

   necessary 
  to 
  surrender 
  those 
  cheaper 
  and 
  better 
  electrical 
  

   materials, 
  and 
  fall 
  back 
  upon 
  the 
  more 
  expensive 
  alloys, 
  

   beginning 
  at 
  platinum-silver. 
  If 
  sufficient 
  time 
  and 
  means 
  

   were 
  at 
  the 
  disposal 
  of 
  metallurgists 
  they 
  might 
  discover 
  the 
  

   secret 
  of 
  permanence 
  in 
  alloys. 
  Germany, 
  with 
  the 
  advan- 
  

   tages 
  of 
  a 
  National 
  Laboratory, 
  has 
  already 
  attacked 
  the 
  

   question, 
  and 
  " 
  manganin 
  " 
  is 
  the 
  result. 
  Its 
  adoption 
  there 
  

   as 
  a 
  satisfactory 
  alloy 
  is 
  directly 
  due 
  to 
  work 
  done 
  upon 
  it 
  by 
  

   the 
  Reichsanstalt. 
  But 
  it 
  has 
  yet 
  to 
  be 
  proved 
  that 
  manganin 
  

   will 
  endure 
  the 
  conditions 
  imposed 
  by 
  the 
  tropics. 
  Moreover, 
  

   the 
  doubt 
  arises 
  as 
  to 
  whether 
  it 
  is 
  desirable 
  to 
  obtain 
  from 
  

   abroad 
  material 
  that 
  ought 
  to 
  be 
  produced 
  by 
  our 
  own 
  country. 
  

   British 
  cable-manufacturers 
  are 
  already 
  importing 
  thousands 
  

   of 
  tons 
  annually 
  of 
  sheathing-wire 
  from 
  Germany; 
  and 
  it 
  

   seems 
  probable 
  that, 
  for 
  the 
  want 
  of 
  a 
  National 
  Laboratory, 
  

   instrument- 
  makers 
  will 
  now 
  get 
  their 
  resistance-wire 
  from 
  that 
  

   same 
  adventurous 
  foreign 
  source. 
  

  

  XYI. 
  Analogy 
  between 
  the 
  Catlwdic 
  Rays 
  and 
  those 
  of 
  Rontgen. 
  

   By 
  Prof. 
  A. 
  Battelli, 
  of 
  the 
  Pisa 
  University*. 
  

  

  TN 
  the 
  'Electrician' 
  of 
  the 
  8th 
  of 
  January, 
  1897, 
  Prof. 
  

   X 
  Silvanus 
  Thompson 
  describes 
  a 
  very 
  simple 
  experiment 
  

   which 
  induces 
  him 
  to 
  admit 
  that 
  there 
  exists 
  within 
  Crookes's 
  

   tubes 
  a 
  special 
  kind 
  of 
  rays, 
  which 
  differ 
  from 
  the 
  cathode 
  rays 
  

   and 
  from 
  those 
  of 
  Rontgen. 
  He 
  observes 
  that 
  on 
  bringing 
  a 
  

   magnet 
  near 
  the 
  focus-tube, 
  as 
  was 
  already 
  known, 
  the 
  fluor- 
  

   escence 
  on 
  the 
  side 
  of 
  the 
  tube 
  facing 
  the 
  small 
  reflectors 
  

   changes 
  its 
  position 
  ; 
  whereas, 
  on 
  the 
  other 
  hand, 
  if 
  a 
  

   fluorescent 
  plate 
  be 
  placed 
  before 
  the 
  tube, 
  the 
  luminous 
  

   stain 
  on 
  it 
  does 
  not 
  shift 
  its 
  position 
  through 
  the 
  effect 
  of 
  

   the 
  magnet. 
  

  

  * 
  Communicated 
  by 
  the 
  Author. 
  

  

  