﻿torn 
  of 
  the 
  collector, 
  and 
  the 
  valves 
  are 
  here 
  shown 
  as 
  

   they 
  appear 
  when 
  arranged 
  for 
  drawing 
  the 
  water 
  from 
  

   the 
  poad, 
  at 
  ebb 
  tide. 
  The 
  inner 
  valve 
  has 
  been 
  slightly 
  

   raised, 
  as 
  will 
  lie 
  observed, 
  by 
  sliding 
  npward 
  its 
  sup- 
  

   port 
  g 
  thi'ongh 
  the 
  grooved 
  trunnion 
  a; 
  and 
  the 
  pressure 
  

   of 
  the 
  water 
  flowing 
  through 
  the 
  iiunie, 
  in 
  the 
  direction 
  

   indicated 
  by 
  the 
  arrow, 
  serves 
  to 
  sioing 
  open 
  the 
  outer 
  

   valve, 
  and 
  to 
  keep 
  it 
  open 
  until 
  the 
  pond 
  is 
  emptied 
  or 
  

   the 
  tide 
  turns. 
  In 
  the 
  latter 
  event 
  the 
  outer 
  valve 
  closes 
  

   automatically 
  until 
  the 
  level 
  of 
  the 
  water 
  without 
  again 
  

   falls 
  below 
  that 
  of 
  the 
  water 
  remaining 
  in 
  the 
  pond 
  

   when 
  its 
  oi^eration 
  is 
  resumed. 
  

  

  Should 
  it 
  be 
  desired, 
  on 
  the 
  other 
  hand, 
  to 
  admit 
  

   water 
  from 
  the 
  river 
  into 
  the 
  pond 
  — 
  at 
  the 
  proper 
  levels 
  

   — 
  the 
  relative 
  positions 
  and 
  operations 
  of 
  the 
  valves 
  

   would 
  of 
  course 
  be 
  reversed. 
  The 
  outer 
  valve 
  should 
  

   then 
  he 
  raised 
  so 
  as 
  to 
  allow 
  the 
  water 
  to 
  enter 
  the 
  

   flume 
  from 
  the 
  river 
  ; 
  and 
  the 
  inner 
  vah-e 
  should 
  be 
  low- 
  

   ered, 
  in 
  turn, 
  to 
  permit 
  it 
  to 
  swing 
  with 
  the 
  current, 
  and 
  

   to 
  close 
  automatically 
  with 
  the 
  cessation 
  of 
  its 
  flow. 
  

  

  The 
  accompanying 
  figures 
  represent 
  portions 
  of 
  the 
  

   above 
  considerably 
  enlarged 
  for 
  the 
  purposes 
  of 
  a 
  more 
  

   detailed 
  description 
  of 
  the 
  several 
  parts. 
  

  

  The 
  flap 
  valve 
  d 
  — 
  which 
  is 
  here 
  represented 
  as 
  being 
  

  

  