﻿Report 
  of 
  the 
  State 
  Geologist. 
  251 
  

  

  The 
  perpendicular 
  opening 
  in 
  the 
  rocks 
  from 
  the 
  surface 
  to 
  the 
  

   bed 
  of 
  rock 
  salt, 
  technically 
  called 
  the 
  shaft, 
  is 
  the 
  only 
  avenue 
  

   of 
  communication 
  between 
  the 
  mine 
  and 
  the 
  outside 
  world. 
  

  

  Not 
  only 
  must 
  all 
  the 
  machinery 
  and 
  materials 
  for 
  mining 
  the 
  

   salt 
  and 
  the 
  salt 
  itself 
  be 
  transported 
  through 
  it, 
  but 
  it 
  is 
  the 
  only 
  

   means 
  of 
  ingress 
  and 
  egress 
  for 
  the 
  men 
  employed 
  in 
  working 
  

   the 
  mine. 
  It 
  is 
  therefore 
  of 
  the 
  utmost 
  importance 
  to 
  the 
  success 
  

   of 
  the 
  enterprise 
  financially 
  and 
  to 
  the 
  safety 
  of 
  the 
  lives 
  of 
  the 
  

   miners 
  that 
  every 
  element 
  of 
  danger 
  in 
  the 
  passage 
  of 
  men 
  or 
  

   material 
  through 
  the 
  shaft 
  be 
  reduced 
  to 
  its 
  minimum. 
  

  

  Perhaps 
  the 
  greatest 
  danger, 
  if 
  not 
  guarded 
  against, 
  would 
  

   arise 
  from 
  the 
  tendency 
  of 
  some 
  kinds 
  of 
  rock 
  to 
  disintegrate, 
  or 
  

   become 
  weakened 
  on 
  exposure 
  to 
  the 
  atmosphere, 
  and 
  allow 
  frag- 
  

   ments 
  to 
  become 
  detached 
  and 
  fall 
  down 
  the 
  shaft, 
  the 
  great 
  

   depth 
  of 
  which 
  would 
  give 
  them 
  the 
  veLocity 
  of 
  a 
  bullet. 
  

  

  In 
  the 
  Livonia 
  shaft 
  all 
  of 
  the 
  rock 
  above 
  the 
  Corniferous 
  lime- 
  

   stone, 
  802 
  feet, 
  was, 
  with 
  the 
  exception 
  of 
  a 
  few 
  thin 
  layers, 
  soft 
  

   shale 
  that 
  crumbled 
  quickly 
  on 
  exposure 
  and 
  was 
  full 
  of 
  joints 
  or 
  

   " 
  slips," 
  i. 
  e. 
  9 
  thin 
  vertical 
  seams 
  filled 
  but 
  not 
  cemented 
  by 
  almost 
  

   transparent 
  calcium 
  carbonate, 
  making 
  very 
  dangerous 
  " 
  ground," 
  

   and 
  it 
  was 
  necessary 
  that 
  the 
  shaft 
  be 
  not 
  only 
  "timbered 
  " 
  but 
  

   " 
  lined 
  " 
  also, 
  which 
  was 
  done 
  with 
  the 
  greatest 
  care 
  and 
  the 
  very 
  

   best 
  material 
  obtainable. 
  

  

  The 
  method 
  of 
  timbering 
  and 
  lining 
  in 
  the 
  Livonia 
  shaft 
  is 
  as 
  

   follows 
  : 
  

  

  When 
  the 
  rock 
  in 
  the 
  bottom 
  of 
  the 
  shaft 
  had 
  been 
  excavated 
  

   by 
  the 
  process 
  briefly 
  described 
  on 
  a 
  preceding 
  page 
  to 
  a 
  depth 
  

   sufficient 
  to 
  avoid 
  danger 
  from 
  the 
  blasting, 
  " 
  hitches 
  " 
  were 
  cut 
  

   into 
  the 
  sides 
  of 
  the 
  shaft 
  one 
  to 
  two 
  feet 
  deep, 
  in 
  such 
  shape 
  as 
  

   to 
  make 
  a 
  flat 
  shoulder 
  of 
  solid 
  rock 
  to 
  support 
  the 
  " 
  bearers." 
  

  

  These 
  bearers, 
  four 
  in 
  number, 
  are 
  of 
  carefully 
  selected 
  white 
  

   oak, 
  twelve 
  by 
  fourteen 
  inches 
  in 
  size, 
  for 
  those 
  placed 
  at 
  the 
  ends 
  

   of 
  the 
  shaft, 
  and 
  ten 
  by 
  fourteen 
  inches 
  for 
  the 
  other 
  two, 
  and 
  are 
  

   long 
  enough 
  to 
  reach 
  across 
  the 
  shaft 
  and 
  to 
  the 
  full 
  depth 
  of 
  the 
  

   hitches, 
  where 
  they 
  are 
  solidly 
  fastened 
  by 
  means 
  of 
  keys 
  and 
  

   wedges. 
  

  

  They 
  are 
  all 
  in 
  the 
  same 
  plane 
  and 
  so 
  placed 
  as 
  to 
  divide 
  the 
  

   shaft 
  into 
  three 
  compartments 
  of 
  equal 
  size. 
  

  

  