﻿6 
  OYSTER 
  BOTTOMS 
  OF 
  LAVACA 
  BAY, 
  TEX. 
  

  

  METHODS 
  OF 
  THE 
  SURVEY. 
  

  

  The 
  methods 
  employed 
  were 
  those 
  pursued 
  in 
  former 
  surveys 
  of 
  like 
  

   character, 
  and 
  are 
  explained 
  in 
  detail 
  in 
  a 
  description 
  of 
  the 
  beds 
  of 
  the 
  

   James 
  River, 
  " 
  from 
  which 
  some 
  of 
  the 
  following 
  is 
  repeated 
  : 
  

  

  A 
  "boat 
  sheet" 
  was 
  prepared, 
  on 
  which 
  were 
  accurately 
  platted 
  

   the 
  positions, 
  as 
  determined 
  by 
  triangulation, 
  of 
  lighthouses, 
  build- 
  

   ings, 
  tripods, 
  etc., 
  used 
  as 
  signals. 
  These 
  data 
  were 
  furnished 
  by 
  the 
  

   United 
  States 
  Coast 
  and 
  Geodetic 
  Survey. 
  

  

  The 
  oyster 
  beds 
  were 
  discovered 
  by 
  soundings 
  with 
  a 
  lead 
  line, 
  but 
  

   principally 
  by 
  means 
  of 
  a 
  length 
  of 
  chain 
  (h'agged 
  over 
  the 
  bottom 
  at 
  

   the 
  end 
  of 
  a 
  copper 
  wire 
  running 
  from 
  the 
  sounding 
  bo 
  at. 
  The 
  wire 
  was 
  

   wound 
  on 
  a 
  reel 
  and 
  its 
  unwound 
  length 
  was 
  adjusted 
  to 
  the 
  depth 
  

   of 
  water 
  and 
  the 
  speed 
  of 
  the 
  launch, 
  so 
  that 
  the 
  chain 
  was 
  always 
  on 
  

   the 
  bottom. 
  Whenever 
  the 
  chain 
  touched 
  a 
  shell 
  or 
  an 
  oyster 
  the 
  

   shock 
  or 
  vibration 
  was 
  transmitted 
  up 
  the 
  wire 
  to 
  the 
  hand 
  of 
  a 
  man 
  

   whose 
  sole 
  duty 
  it 
  was 
  to 
  give 
  heed 
  to 
  such 
  signals 
  and 
  report 
  them 
  to 
  

   the 
  recorder. 
  

  

  The 
  launches 
  from 
  which 
  the 
  soundings 
  were 
  made 
  were 
  run 
  at 
  a 
  

   speed 
  of 
  between 
  8 
  and 
  4 
  miles 
  per 
  hour. 
  At 
  intervals 
  of 
  three 
  

   minutes 
  — 
  in 
  some 
  cases 
  two 
  minutes 
  — 
  the 
  position 
  of 
  the 
  boat 
  was 
  

   determined 
  by 
  two 
  simultaneous 
  sextant 
  observations 
  of 
  the 
  angles 
  

   between 
  a 
  set 
  of 
  three 
  signals, 
  the 
  middle 
  one 
  of 
  which 
  was 
  common 
  to 
  

   the 
  two 
  angles, 
  the 
  position 
  being 
  immediately 
  platted 
  on 
  the 
  boat 
  

   sheet. 
  At 
  regular 
  intervals 
  of 
  15 
  seconds, 
  as 
  measured 
  by 
  a 
  clock 
  

   under 
  the 
  observation 
  of 
  the 
  recorder, 
  the 
  leadsman 
  made 
  a 
  sounding 
  

   and 
  reported 
  to 
  the 
  recorder 
  the 
  depth 
  of 
  the 
  water 
  and 
  the 
  character 
  

   of 
  the 
  bottom, 
  immediately 
  after 
  which 
  the 
  man 
  at 
  the 
  wire 
  reported 
  

   the 
  character 
  of 
  the 
  chain 
  indications 
  since 
  the 
  last 
  sounding 
  — 
  that 
  is, 
  

   whether 
  they 
  showed 
  barren 
  bottom 
  or 
  dense, 
  scattering, 
  or 
  very 
  

   scattering 
  growths 
  of 
  oysters. 
  

  

  With 
  the 
  boat 
  running 
  at 
  3 
  miles 
  per 
  hour 
  the 
  soundings 
  were 
  

   between 
  60 
  and 
  70 
  feet 
  apart, 
  and, 
  as 
  the 
  speed 
  of 
  the 
  boat 
  was 
  

   uniform, 
  the 
  location 
  of 
  each 
  was 
  determinable 
  within 
  a 
  yard 
  or 
  two 
  

   by 
  dividing 
  the 
  platted 
  distance 
  between 
  the 
  positions 
  determined 
  

   by 
  the 
  sextant 
  by 
  the 
  number 
  of 
  soundings. 
  The 
  chain, 
  of 
  course, 
  

   gave 
  a 
  continuous 
  indication 
  of 
  the 
  character 
  of 
  the 
  bottom, 
  but 
  the 
  

   record 
  was 
  made 
  at 
  the 
  regular 
  15-second 
  intervals 
  observed 
  in 
  

   sounding. 
  

  

  The 
  chain, 
  while 
  indicating 
  the 
  absence 
  or 
  the 
  relative 
  abundance 
  

   of 
  objects 
  on 
  the 
  bottom, 
  gives 
  no 
  information 
  as 
  to 
  whether 
  they 
  

   are 
  shells 
  or 
  oysters, 
  nor, 
  if 
  the 
  latter, 
  their 
  size 
  and 
  condition. 
  To 
  

   obtain 
  these 
  data 
  it 
  was 
  necessary 
  to 
  supplement 
  the 
  observations 
  

   already 
  described 
  by 
  others 
  more 
  definite 
  in 
  respect 
  to 
  the 
  desired 
  

  

  a 
  Moore, 
  H. 
  F.: 
  Condition 
  and 
  extent 
  of 
  the 
  oyster 
  beds 
  of 
  James 
  River, 
  Va. 
  Bureau 
  of 
  Fisheries 
  

   Document 
  no. 
  729. 
  

  

  