﻿JUNE 
  19, 
  1922 
  PUTNAM: 
  LIGHTHOUSE 
  SERVICE 
  285 
  

  

  Isle 
  of 
  Wight, 
  with 
  the 
  advice 
  of 
  Lord 
  Rayleigh. 
  In 
  recent 
  years 
  com- 
  

   parative 
  tests 
  of 
  apparatus 
  have 
  been 
  made 
  by 
  the 
  Lighthouse 
  Ser- 
  

   vice 
  from 
  time 
  to 
  time, 
  and 
  the 
  fog 
  signal 
  station 
  at 
  Execution 
  Rocks 
  

   in 
  Long 
  Island 
  Sound 
  has 
  recently 
  been 
  fitted 
  up 
  for 
  systematic 
  tests. 
  

  

  Lighthouse 
  construction 
  and 
  engineering. 
  — 
  Unusual 
  engineering 
  prob- 
  

   lems 
  are 
  involved 
  in 
  the 
  lighthouse 
  work 
  both 
  in 
  the 
  fixed 
  and 
  floating 
  

   structures. 
  Most 
  of 
  the 
  important 
  lighthouses 
  have 
  been 
  built 
  on 
  

   exposed 
  sites, 
  and 
  many 
  on 
  submarine 
  sites, 
  or 
  partially 
  submerged 
  

   reefs, 
  involving 
  difficult 
  engineering 
  design 
  and 
  construction. 
  The 
  

   problems 
  will 
  be 
  illustrated 
  by 
  a 
  few 
  examples. 
  Minots 
  Ledge 
  light- 
  

   house, 
  south 
  of 
  Boston, 
  was 
  built 
  on 
  a 
  reef 
  bare 
  only 
  at 
  low 
  water 
  and 
  

   for 
  a 
  small 
  area, 
  and 
  exposed 
  to 
  the 
  Atlantic. 
  The 
  reef 
  had 
  to 
  be 
  cut 
  

   to 
  receive 
  the 
  foundation 
  of 
  the 
  tower; 
  during 
  the 
  first 
  year 
  only 
  130 
  

   working 
  hours 
  were 
  obtained 
  on 
  the 
  rock, 
  and 
  the 
  work 
  was 
  prosecuted 
  

   for 
  more 
  than 
  3 
  years 
  before 
  a 
  single 
  stone 
  was 
  laid. 
  After 
  5 
  years' 
  

   work 
  a 
  massive 
  stone 
  tower 
  was 
  erected, 
  which 
  has 
  now 
  stood 
  for 
  over 
  

   60 
  years; 
  on 
  occasions 
  the 
  waves 
  go 
  over 
  the 
  top 
  of 
  the 
  tower, 
  97 
  

   feet 
  above 
  the 
  water. 
  

  

  On 
  the 
  Pacific 
  coast, 
  a 
  notable 
  lighthouse 
  is 
  that 
  at 
  Tillamook 
  

   Rock, 
  south 
  of 
  the 
  mouth 
  of 
  the 
  Columbia 
  River. 
  Here 
  the 
  top 
  of 
  the 
  

   rock 
  had 
  to 
  be 
  blasted 
  off 
  to 
  give 
  a 
  site 
  for 
  the 
  structure, 
  and 
  special 
  

   protection 
  had 
  to 
  be 
  provided 
  for 
  workmen 
  and 
  materials, 
  as 
  in 
  storms 
  

   the 
  waves 
  go 
  over 
  the 
  entire 
  rock. 
  The 
  lantern 
  of 
  the 
  completed 
  struc- 
  

   ture 
  is 
  133 
  feet 
  above 
  the 
  sea, 
  but 
  in 
  severe 
  storms 
  rocks 
  have 
  been 
  

   thrown 
  through 
  the 
  lantern 
  glass. 
  

  

  A 
  number 
  of 
  lighthouses 
  have 
  been 
  erected 
  in 
  open 
  water 
  on 
  sand 
  

   bottom, 
  with 
  caissons 
  sunk 
  by 
  the 
  pneumatic 
  process. 
  The 
  first 
  so 
  

   built 
  in 
  this 
  country 
  was 
  the 
  Fourteen 
  Foot 
  Bank 
  lighthouse 
  in 
  Del- 
  

   aware 
  Bay, 
  standing 
  in 
  20 
  feet 
  of 
  water. 
  The 
  caisson 
  was 
  sunk 
  to 
  a 
  

   depth 
  of 
  33 
  feet 
  into 
  the 
  sand, 
  using 
  a 
  timber 
  working 
  chamber 
  40 
  

   feet 
  square. 
  

  

  Marking 
  the 
  edge 
  of 
  the 
  Florida 
  reefs 
  are 
  six 
  tall 
  iron 
  lighthouses, 
  

   five 
  of 
  which 
  stand 
  in 
  shallow 
  water. 
  As 
  the 
  material 
  of 
  the 
  coral 
  

   reefs 
  was 
  not 
  solid 
  enough 
  to 
  sustain 
  on 
  piles 
  alone 
  the 
  weight 
  of 
  these 
  

   towers, 
  from 
  115 
  to 
  160 
  feet 
  in 
  height, 
  sufficient 
  support 
  was 
  obtained 
  

   by 
  driving 
  wrought 
  iron 
  piles 
  into 
  the 
  coral, 
  to 
  a 
  shoulder 
  resting 
  against 
  

   iron 
  discs 
  8 
  feet 
  in 
  diameter, 
  giving 
  a 
  large 
  bearing 
  on 
  the 
  surface 
  of 
  

   the 
  coral. 
  

  

  Vessels 
  and 
  floating 
  aids. 
  — 
  More 
  than 
  half 
  of 
  the 
  aids 
  maintained 
  

   are 
  floating, 
  and 
  these 
  are 
  of 
  great 
  value 
  to 
  mariners, 
  as 
  they 
  can 
  be 
  

  

  