﻿382 
  Webster 
  — 
  Producing 
  a 
  Constant 
  Angular 
  velocity. 
  

  

  The 
  run 
  of 
  five 
  minutes 
  was 
  reasonably 
  steady, 
  the 
  oscillations 
  

   being 
  slow, 
  and 
  the 
  greatest 
  oscillation 
  of 
  the 
  spot 
  in 
  the 
  whole 
  

   period 
  being 
  not 
  over 
  seventy 
  degrees. 
  Later 
  the 
  oscillations 
  

   became 
  worse, 
  and 
  then 
  a 
  complete 
  to 
  and 
  fro 
  oscillation 
  of 
  

   forty 
  -five 
  degrees 
  on 
  each 
  side 
  of 
  the 
  mean 
  took 
  place 
  in 
  eight 
  

   seconds, 
  corresponding 
  to 
  a 
  maximum 
  variation 
  from 
  the 
  mean 
  

   of 
  one 
  part 
  in 
  eight 
  hundred. 
  These 
  were 
  about 
  the 
  worst 
  

   figures 
  obtained. 
  The 
  next 
  run 
  of 
  twenty-three 
  minutes 
  main- 
  

   tained 
  the 
  synchronism 
  until 
  the 
  voltage 
  had 
  dropped 
  from 
  

   46*5 
  to 
  45 
  volts. 
  Further 
  runs 
  were, 
  

  

  Volts, 
  53'5. 
  Amperes, 
  1J^'5. 
  Auxiliary 
  current 
  — 
  Amperes, 
  6'2. 
  

  

  The 
  run 
  lasted 
  half 
  an 
  hour 
  and 
  stopped 
  only 
  on 
  account 
  of 
  

   the 
  failure 
  of 
  the 
  pump 
  belonging 
  to 
  the 
  bre.ak 
  (see 
  below). 
  In 
  

   this 
  time 
  the 
  voltage 
  had 
  gone 
  up 
  one 
  volt, 
  and 
  the 
  amperes 
  

   one-half 
  ampere. 
  

  

  Volts, 
  69. 
  Amperes, 
  19'£. 
  Auxiliary 
  current 
  — 
  Amperes, 
  6. 
  

  

  Hun 
  of 
  fifteen 
  minutes. 
  Oscillation 
  very 
  slight, 
  even 
  with 
  

   variation 
  of 
  two 
  volts 
  and 
  a 
  quarter 
  and 
  one 
  quarter 
  ampere 
  in 
  

   the 
  supply. 
  

  

  Volts, 
  97. 
  Amperes, 
  12-5. 
  Auxiliary 
  current— 
  Amperes, 
  Jf'25. 
  

  

  When 
  the 
  synchronism 
  failed 
  it 
  was 
  on 
  account 
  of 
  the 
  large 
  

   change 
  in 
  load 
  caused 
  by 
  slipping 
  of 
  the 
  driving 
  belt. 
  

  

  It 
  is 
  thus 
  evident 
  that 
  the 
  method 
  is 
  a 
  practical 
  one 
  up 
  to 
  

   more 
  than 
  one 
  and 
  a 
  half 
  horse-power. 
  This 
  is 
  more 
  than 
  

   would 
  be 
  needed 
  in 
  by 
  far 
  the 
  greater 
  number 
  of 
  its 
  obvious 
  

   applications. 
  The 
  method 
  seems 
  to 
  me 
  of 
  undoubted 
  useful- 
  

   ness 
  in 
  absolute 
  determinations, 
  and 
  may 
  be 
  useful 
  in 
  connec- 
  

   tion 
  with 
  the 
  driving 
  of 
  telescopes. 
  It 
  is 
  difficult 
  to 
  get 
  exact 
  

   statements 
  as 
  to 
  the 
  accuracy 
  of 
  existing 
  governors, 
  so 
  that 
  I 
  

   am 
  unable 
  to 
  state 
  whether 
  the 
  method 
  here 
  given 
  is 
  suffi- 
  

   ciently 
  accurate 
  or 
  not. 
  It 
  has 
  been 
  used 
  in 
  the 
  laboratory 
  of 
  

   Clark 
  University 
  for 
  a 
  number 
  of 
  purposes, 
  one 
  of 
  which 
  is 
  

   described 
  by 
  Mr. 
  C. 
  A. 
  Saunders 
  in 
  an 
  article 
  in 
  the 
  Physical 
  

   Review, 
  Sept.-Oct., 
  1896. 
  By 
  the 
  same 
  means 
  a 
  siren 
  is 
  con- 
  

   verted 
  into 
  an 
  instrument 
  of 
  precision, 
  far 
  superior 
  to 
  appa- 
  

   ratus 
  costing 
  much 
  more. 
  A 
  chronograph 
  for 
  astronomical 
  

   purposes 
  has 
  been 
  constructed 
  on 
  the 
  same 
  principle, 
  whose 
  

   performance 
  will 
  be 
  described 
  elsewhere. 
  

  

  