﻿oil 
  

  

  of 
  wliicli 
  the 
  gate 
  may 
  be 
  raised 
  or 
  lowered. 
  "C, 
  (7, 
  C" 
  

   represent 
  erib-work, 
  filled 
  with 
  stones, 
  and 
  sustaining 
  

   in 
  position 
  the 
  screens 
  s, 
  s 
  and 
  o, 
  o, 
  wliich 
  are 
  arranged 
  

  

  to 
  slide 
  in 
  their 
  respective 
  grooves, 
  similarly 
  to 
  those 
  

   already 
  described. 
  

  

  A 
  tinnie 
  or 
  trunk 
  of 
  somewhat 
  simpler 
  and 
  cheaper 
  

   design 
  ; 
  which 
  may 
  be 
  constructed 
  by 
  hollowing 
  ont 
  

   one 
  side 
  of 
  a 
  stout 
  log, 
  for 
  nearly 
  its 
  entire 
  length, 
  

   and 
  covering 
  the 
  groove 
  thus 
  formed 
  with 
  j)iecesof 
  thick 
  

   plank, 
  is 
  also 
  figured; 
  the 
  bark 
  should 
  be 
  allowed 
  to 
  

   remain 
  undisturbed, 
  where 
  practicable, 
  for 
  the 
  sake 
  of 
  

   the 
  protection 
  which 
  it 
  affords 
  to 
  the 
  wood. 
  The 
  gen- 
  

   eral 
  arrangement 
  of 
  the 
  flume 
  and 
  its 
  valves 
  is 
  so 
  plainly 
  

   indicated 
  in 
  the 
  diagram 
  as 
  to 
  rendei- 
  further 
  descrip- 
  

   tion 
  unnecessary; 
  it 
  will 
  only 
  be 
  reuiarked. 
  therefore, 
  

   that 
  as 
  the 
  valves 
  do 
  not 
  Avork 
  automatically, 
  such 
  a 
  

   "plug-trunk" 
  — 
  as 
  it 
  is 
  called 
  — 
  would 
  appear 
  to 
  be 
  better 
  

   adapted 
  for 
  ponds 
  located 
  in 
  other 
  than 
  tidal 
  i-egions. 
  

  

  