﻿148 
  2'ransaciions.--Miscdlaiiemis. 
  

  

  thick. 
  At 
  Cranz, 
  on 
  tlie 
  Baltic, 
  rows 
  of 
  piles 
  8x8 
  inches 
  and 
  10 
  to 
  12 
  feet 
  

   long, 
  spaced 
  13 
  inches 
  g,part, 
  have 
  been 
  successful, 
  with 
  a 
  breastwork 
  of 
  

   IDiles 
  and 
  fascines. 
  Breastworks 
  are 
  often 
  required 
  in 
  cases 
  of 
  low 
  foreshore 
  

   or 
  where 
  a 
  cliff 
  is 
  exposed 
  to 
  rapid 
  erosion 
  by 
  the 
  sea. 
  

  

  Beaches 
  have 
  also 
  been 
  successfully 
  formed 
  along 
  the 
  sea 
  barriers 
  of 
  recla= 
  

   matioir 
  works 
  by 
  means 
  of 
  groynes. 
  At 
  Sunderland, 
  successive 
  additions 
  were 
  

   made 
  to 
  the 
  reclaimed 
  area 
  as 
  the 
  beach 
  formed. 
  In 
  1874-5 
  the 
  author 
  had 
  

   ■charge 
  of 
  similar 
  works 
  at 
  Ayr 
  ; 
  a 
  reclamation 
  of 
  24 
  acres 
  of 
  foreshore 
  for 
  a 
  

   dock 
  was 
  made, 
  and 
  six 
  groynes 
  with 
  stone 
  filling, 
  each 
  150 
  feet 
  in 
  length 
  

   and 
  260 
  feet 
  apart 
  (see 
  figs. 
  8 
  and 
  4), 
  were 
  constructed 
  along 
  the 
  line 
  of 
  sea 
  

   barrier 
  in 
  order 
  to 
  collect 
  a 
  beach 
  in 
  front 
  of 
  it. 
  In 
  the 
  first 
  year 
  after 
  their 
  

   erection 
  a 
  rise 
  of 
  two 
  to 
  three 
  feet 
  took 
  place. 
  With 
  main 
  piles, 
  having 
  a 
  

   nett 
  length 
  of 
  31 
  lin. 
  feet, 
  the 
  rate 
  per 
  yard 
  run 
  with 
  scrub 
  and 
  stone 
  filling, 
  

   instead 
  of 
  wholly 
  stone 
  as 
  shown 
  in 
  the 
  drawing, 
  would 
  be 
  18 
  ^^q 
  lin. 
  feet 
  

   main 
  piles, 
  2|- 
  CBM 
  timber 
  in 
  way-balks, 
  waliugs, 
  cross-ties, 
  and 
  planking, 
  

   and 
  50 
  lbs. 
  iron 
  work 
  in 
  bolts, 
  3f 
  lbs. 
  spikes 
  and 
  21 
  lbs. 
  in 
  shoes 
  ; 
  scrub 
  

   and 
  stone 
  filling 
  17-| 
  cubic 
  yards. 
  The 
  cost 
  of 
  6 
  groynes, 
  each 
  66 
  lin. 
  yards, 
  

   would 
  be 
  about 
  £5,300. 
  

  

  On 
  spits 
  and 
  low 
  beaches 
  exposed 
  to 
  encroachment, 
  groynes 
  require 
  to 
  be 
  

   constructed 
  first, 
  and 
  then 
  rows 
  of 
  fascines 
  and 
  scrub 
  can 
  be 
  placed 
  with 
  

   advantage 
  along 
  the 
  crest 
  of 
  the 
  beach. 
  The 
  scrub 
  placed 
  along 
  the 
  beach 
  

   at 
  Hokitika 
  probably 
  assisted 
  the 
  accumulation 
  of 
  sand 
  behind 
  it; 
  but 
  

   without 
  groynes 
  it 
  cannot 
  affect 
  the 
  action 
  of 
  the 
  sea 
  at 
  the 
  foot 
  of 
  the 
  beach 
  

   where 
  the 
  erosion 
  is 
  greatest, 
  and 
  encroachment 
  proceeds 
  until 
  the 
  scrub 
  is 
  

   undermined. 
  The 
  rough 
  cribwork 
  groynes 
  that 
  Mr. 
  Eochfort 
  placed 
  on 
  the 
  

   beach 
  in 
  1867 
  and 
  1868 
  * 
  were 
  efforts 
  in 
  the 
  right 
  direction, 
  but 
  a 
  much 
  

   greater 
  length 
  would 
  be 
  required 
  for 
  efficient 
  protection. 
  The 
  formation 
  of 
  

   a 
  broad 
  beach 
  upon 
  which 
  the 
  waves 
  can 
  expend 
  their 
  force 
  is 
  of 
  far 
  greater 
  

   importance 
  than 
  a 
  high 
  narrow 
  ridge 
  which 
  must 
  always 
  be 
  liable 
  to 
  be 
  

   washed 
  down 
  by 
  heavy 
  seas. 
  

  

  The 
  fetch 
  or 
  reach 
  of 
  open 
  sea 
  is 
  considerably 
  greater 
  here 
  than 
  at 
  those 
  

   places 
  that 
  I 
  have 
  mentioned, 
  and 
  the 
  waves 
  from 
  that 
  cause 
  must 
  be 
  larger 
  ; 
  

   but 
  the 
  depth 
  of 
  water 
  off' 
  Hokitika 
  at 
  ^ 
  mile 
  and 
  1 
  mile 
  distance 
  is 
  26 
  and 
  

   42 
  feet, 
  at 
  Sunderland 
  it 
  is 
  27 
  and 
  52 
  feet; 
  while 
  the 
  range 
  of 
  spring 
  tides 
  

   at 
  Hokitika 
  is 
  9 
  feet, 
  and 
  at 
  Sunderland 
  it 
  is 
  14 
  feet 
  6 
  inches 
  ; 
  and 
  it 
  must 
  

   follow 
  that 
  the 
  power 
  of 
  the 
  waves 
  are 
  more 
  broken 
  here, 
  having 
  to 
  pass 
  

   over 
  shallower 
  water. 
  I 
  beheve 
  the 
  design 
  shown 
  in 
  figs. 
  1 
  and 
  2 
  would 
  be 
  

   efficacious, 
  and 
  it 
  has 
  the 
  merit 
  of 
  presenting 
  the 
  minimum 
  amount 
  of 
  

   surface 
  to 
  the 
  seas. 
  

  

  * 
  See 
  Trans. 
  N.Z. 
  Inst., 
  1871, 
  Vol. 
  IV., 
  p. 
  299. 
  

  

  