﻿58 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [56] 
  

  

  APPENDIX. 
  

  

  Chief 
  Engineer's 
  Office, 
  U. 
  S. 
  Navy- 
  Yard, 
  

  

  Washington, 
  I). 
  C, 
  December 
  19, 
  1885. 
  

  

  Sir 
  : 
  In 
  compliance 
  with 
  instructions 
  of 
  the 
  Bureau 
  of 
  Steam 
  Engi- 
  

   neering, 
  dated 
  the 
  15th, 
  and 
  your 
  order 
  dated 
  the 
  16th 
  instant, 
  the 
  

   Board 
  appointed 
  to 
  examine 
  the 
  device 
  described 
  as 
  "Baird's 
  Annun- 
  

   ciator," 
  have 
  examined 
  the 
  apparatus, 
  observed 
  its 
  operation, 
  and 
  beg 
  

   leave 
  to 
  report 
  as 
  follows 
  : 
  

  

  The 
  object 
  of 
  the 
  device 
  is 
  to 
  indicate 
  upon 
  deck, 
  to 
  the 
  easy 
  inspec- 
  

   tion 
  of 
  the 
  officer 
  in 
  charge 
  of 
  the 
  deck 
  or 
  his 
  assistants, 
  the 
  direction 
  

   of 
  the 
  movement 
  of 
  the 
  engines, 
  whether 
  ahead 
  or 
  aback. 
  

  

  While 
  the 
  engines 
  are 
  working 
  ahead 
  an 
  index 
  revolves 
  in 
  the 
  direc- 
  

   tion 
  in 
  which 
  an 
  arrow, 
  on 
  its 
  free 
  extremity, 
  points; 
  upon 
  reversing 
  

   the 
  engines 
  the 
  motion 
  of 
  the 
  index 
  is 
  reversed. 
  

  

  The 
  mechanism 
  immediately 
  employed 
  in 
  producing 
  these 
  movements 
  

   is 
  inclosed 
  in 
  a 
  case, 
  of 
  which 
  the 
  dial 
  over 
  which 
  the 
  index 
  revolves 
  is 
  

   the 
  face. 
  The 
  index 
  is 
  mounted 
  upon 
  a 
  shaft 
  or 
  spindle, 
  which 
  carries 
  

   a 
  toothed 
  wheel. 
  

  

  The 
  wheel 
  and 
  spindle 
  are 
  turned 
  by 
  the 
  revolutions 
  of 
  a 
  second 
  spin- 
  

   dle 
  placed 
  at 
  right 
  angles 
  with 
  the 
  first, 
  carrying 
  a 
  worm 
  or 
  endless 
  

   screw, 
  the 
  threads 
  of 
  which 
  mesh 
  with 
  the 
  teeth 
  of 
  the 
  wheel. 
  The 
  

   second 
  spindle 
  carries 
  also 
  a 
  series 
  of 
  fans, 
  arranged 
  like 
  the 
  blades 
  of 
  

   a 
  screw 
  propeller, 
  or 
  like 
  the 
  vanes 
  of 
  the 
  common 
  anemometer. 
  

  

  By 
  means 
  of 
  an 
  air 
  current, 
  which 
  ilows 
  in 
  one 
  direction 
  when 
  the 
  

   ship's 
  engines 
  are 
  going 
  ahead 
  and 
  in* 
  the 
  opposite 
  direction 
  when 
  they 
  

   are 
  backing, 
  the 
  fans 
  and 
  their 
  spindle 
  are 
  rapidly 
  revolved, 
  and 
  the 
  

   proper 
  motion 
  transmitted 
  through 
  the 
  spiral 
  gearing 
  to 
  the 
  index. 
  

   The 
  movement 
  of 
  the 
  index 
  is 
  moderate 
  in 
  speed, 
  but 
  the 
  speed 
  is 
  va- 
  

   riable 
  willi 
  the 
  speed 
  of 
  the 
  engine, 
  and 
  incidentally 
  affords 
  a 
  means 
  of 
  

   estimating, 
  by 
  the 
  eye, 
  the 
  speed 
  as 
  well 
  as 
  the. 
  direction 
  of 
  the 
  move- 
  

   ment 
  of 
  the 
  engines 
  and 
  the 
  ship. 
  

  

  The 
  air 
  current 
  is 
  derived 
  from 
  a 
  small 
  rotary 
  blower 
  placed 
  near 
  tin 
  1 
  

   engine 
  shaft, 
  and 
  turned 
  by 
  it 
  through 
  the 
  operation 
  of 
  belts. 
  When 
  

   turned 
  in 
  one 
  direction 
  the 
  blower 
  draws 
  the 
  air 
  from 
  the 
  vanes 
  of 
  the 
  

   annunciator 
  through 
  a 
  pipe, 
  in 
  one 
  enlarged 
  extremity 
  of 
  which, 
  form- 
  

   ing 
  a 
  mouth, 
  the 
  vanes 
  revolve. 
  When 
  turned 
  in 
  the 
  opposite 
  direction 
  

   the 
  air 
  is 
  driven 
  through 
  the 
  connecting 
  pipe 
  to 
  the 
  vanes, 
  and 
  the 
  

   direction 
  of 
  the 
  movement 
  of 
  the 
  latter, 
  upon 
  the 
  instant, 
  reversed. 
  

  

  It 
  is 
  a 
  very 
  great 
  advantage 
  to 
  the 
  person 
  maneuvering 
  the 
  ship 
  to 
  

   know, 
  without 
  the 
  delay 
  attending 
  inquiry 
  or 
  observation 
  of 
  the 
  move- 
  

   ment 
  of 
  the 
  ship 
  herself, 
  exactly 
  what 
  the 
  latter 
  is 
  to 
  be. 
  Should 
  mis- 
  

   take 
  be 
  made 
  it 
  will 
  be 
  apparent 
  before 
  it 
  is 
  too 
  late 
  to 
  correct 
  it. 
  

  

  