﻿Chemistry 
  and 
  Physics. 
  237 
  

  

  the 
  temperature 
  of 
  melting 
  ice 
  fourteen 
  and 
  four 
  thousand 
  five 
  hundred 
  and 
  

   twenty-one 
  ten-thousandths 
  grams 
  in 
  mass, 
  of 
  a 
  constant 
  cross-sectional 
  area, 
  and 
  

   of 
  the 
  length 
  of 
  one 
  hundred 
  and 
  six 
  and 
  three-tenths 
  centimeters. 
  

  

  Second. 
  The 
  unit 
  of 
  current 
  shall 
  be 
  what 
  is 
  known 
  as 
  the 
  international 
  ampere, 
  

   which 
  is 
  one-tenth 
  of 
  the 
  unit 
  of 
  current 
  of 
  the 
  centimeter-gram-second 
  system 
  of 
  

   electro-magnetic 
  units, 
  and 
  is 
  the 
  practical 
  equivalent 
  of 
  the 
  unvarying 
  current, 
  

   which, 
  when 
  passed 
  through 
  a 
  solution 
  of 
  nitrate 
  of 
  silver 
  in 
  water 
  in 
  accordance 
  

   with 
  standard 
  specifications, 
  deposits 
  silver 
  at 
  the 
  rate 
  of 
  one 
  thousand 
  one 
  hun- 
  

   dred 
  and 
  eighteen 
  millionths 
  of 
  a 
  gram 
  per 
  second. 
  

  

  Third. 
  The 
  unit 
  of 
  electro-motive 
  force 
  shall 
  be 
  what 
  is 
  known 
  as 
  the 
  inter- 
  

   national 
  volt, 
  which 
  is 
  the 
  electro-motive 
  force 
  that, 
  steadily 
  applied 
  to 
  a 
  conductor 
  

   whose 
  resistance 
  is 
  one 
  international 
  ohm, 
  will 
  produce 
  a 
  current 
  of 
  an 
  interna- 
  

   tional 
  ampere, 
  and 
  is 
  practically 
  equivalent 
  to 
  one 
  thousand 
  fourteen 
  hundred 
  and 
  

   thirty-fourths 
  of 
  the 
  electro-motive 
  force 
  between 
  the 
  poles 
  or 
  electrodes 
  of 
  the 
  

   voltaic 
  cell 
  known 
  as 
  Clark's 
  cell, 
  at 
  a 
  temperature 
  of 
  fifteen 
  degrees 
  centigrade, 
  

   and 
  prepared 
  in 
  the 
  manner 
  described 
  in 
  the 
  standard 
  specifications. 
  

  

  Fourth. 
  The 
  unit 
  of 
  quantity 
  shall 
  be 
  what 
  is 
  known 
  as 
  the 
  international 
  coulomb, 
  

   which 
  is 
  the 
  quantity 
  of 
  electricity 
  transferred 
  by 
  a 
  current 
  of 
  one 
  international 
  

   ampere 
  in 
  one 
  second. 
  

  

  Fifth. 
  The 
  unit 
  of 
  capacity 
  shall 
  be 
  what 
  is 
  known 
  as 
  the 
  international 
  farad, 
  

   which 
  is 
  the 
  capacity 
  of 
  a 
  condenser 
  charged 
  to 
  a 
  potential 
  of 
  one 
  international 
  volt 
  

   by 
  one 
  international 
  coulomb 
  of 
  electricity. 
  

  

  Sixth. 
  The 
  unit 
  of 
  work 
  shall 
  be 
  the 
  Joule, 
  which 
  is 
  equal 
  to 
  ten 
  million 
  units 
  of 
  

   work 
  in 
  the 
  centimeter-gram-second 
  system, 
  and 
  which 
  is 
  practically 
  equivalent 
  to 
  

   the 
  energy 
  expended 
  in 
  one 
  second 
  by 
  an 
  international 
  ampere 
  in 
  an 
  international 
  

   ohm. 
  

  

  Seventh. 
  The 
  unit 
  of 
  power 
  shall 
  be 
  the 
  "Watt, 
  which 
  is 
  equal 
  to 
  ten 
  million 
  units 
  

   of 
  power 
  in 
  the 
  centimeter-gram- 
  second 
  system, 
  and 
  which 
  is 
  practically 
  equivalent 
  

   to 
  the 
  work 
  done 
  at 
  the 
  rate 
  of 
  one 
  Joule 
  per 
  second. 
  

  

  Eighth. 
  The 
  unit 
  of 
  induction 
  shall 
  be 
  the 
  Henry, 
  which 
  is 
  the 
  induction 
  in 
  a 
  

   circuit 
  when 
  the 
  electro-motive 
  force 
  induced 
  in 
  this 
  circuit 
  is 
  one 
  international 
  

   volt 
  while 
  the 
  inducing 
  current 
  varies 
  at 
  the 
  rate 
  of 
  one 
  Ampere 
  per 
  second. 
  

  

  Sec. 
  2. 
  That 
  it 
  shall 
  be 
  the 
  duty 
  of 
  the 
  National 
  Academy 
  of 
  Sciences 
  to 
  

   prescribe 
  and 
  publish, 
  as 
  soon 
  as 
  possible 
  after 
  the 
  passage 
  of 
  this 
  Act, 
  such 
  

   specifications 
  of 
  details 
  as 
  shall 
  be 
  necessary 
  for 
  the 
  practical 
  application 
  of 
  the 
  

   definitions 
  of 
  the 
  ampere 
  and 
  volt 
  hereinbefore 
  given, 
  and 
  such 
  specifications 
  shall 
  

   be 
  the 
  standard 
  specifications 
  herein 
  mentioned. 
  

  

  To 
  meet 
  this 
  requirement 
  of 
  Congress, 
  it 
  was 
  necessary, 
  in 
  

   accordance 
  with 
  the 
  constitution 
  of 
  the 
  National 
  Academy 
  of 
  

   Sciences, 
  to 
  appoint 
  a 
  special 
  committee 
  to 
  consider 
  the 
  subject. 
  

   This 
  was 
  done 
  as 
  soon 
  as 
  an 
  official 
  copy 
  of 
  the 
  law 
  was 
  received 
  

   from 
  the 
  State 
  Department. 
  The 
  committee, 
  selected 
  from 
  mem- 
  

   bers 
  of 
  the 
  National 
  Academy, 
  was 
  as 
  follows 
  : 
  — 
  

  

  Prof. 
  H. 
  A. 
  Rowland, 
  Chairman, 
  Johns 
  Hopkins 
  University, 
  Baltimore. 
  

  

  Gen. 
  H. 
  L. 
  Abbot, 
  United 
  States 
  Engineers, 
  New 
  York. 
  

  

  Prof. 
  G-. 
  F. 
  Barker, 
  University 
  of 
  Pennsylvania, 
  Philadelphia. 
  

  

  Prof. 
  J. 
  Trowbridge, 
  Harvard 
  University, 
  Cambridge. 
  

  

  Prof. 
  C. 
  S. 
  Hastings, 
  Yale 
  University, 
  New 
  Haven. 
  

  

  Dr. 
  C. 
  Barus, 
  Smithsonian 
  Institution, 
  "Washington. 
  

  

  Prof. 
  A. 
  A. 
  Michelson, 
  University 
  of 
  Chicago, 
  Chicago. 
  

  

  The 
  committee 
  completed 
  the 
  work 
  assigned 
  to 
  them, 
  and 
  the 
  

   specifications 
  they 
  prepared 
  meet 
  the 
  requirement 
  of 
  the 
  law, 
  

   and 
  are 
  also 
  in 
  accord 
  with 
  international 
  agreement. 
  

  

  The 
  report 
  of 
  this 
  committee, 
  approved 
  by 
  all 
  its 
  members, 
  

   was 
  submitted 
  to 
  the 
  National 
  Academy 
  of 
  Sciences 
  at 
  a 
  special 
  

  

  