﻿LIMESTONES 
  OF 
  NEW 
  YORK 
  AND 
  THEIR 
  ECONOMIC 
  VALUE 
  42T 
  

  

  dition 
  both 
  as 
  regards 
  the 
  manufacture 
  and 
  purchasing 
  of 
  cement, 
  

   and 
  some 
  definite 
  agreement 
  on 
  these 
  points 
  is 
  very 
  desirable. 
  

  

  Uses 
  of 
  cement 
  

  

  Hydraulic 
  cements 
  are 
  employed 
  in 
  America 
  to 
  some 
  extent 
  for 
  

   all 
  the 
  purposes 
  for 
  which 
  these 
  products 
  have 
  been 
  used 
  in 
  Eu- 
  

   rope 
  but 
  the 
  relative 
  development 
  for 
  different 
  uses 
  has 
  been 
  dis- 
  

   tinctly 
  different 
  here 
  from 
  that 
  abroad. 
  For 
  sidewalk 
  pavements 
  

   Portland 
  cement 
  concrete 
  has 
  probably 
  been 
  employed 
  in 
  America 
  

   to 
  a 
  greater 
  relative 
  extent 
  than 
  anywhere 
  else 
  in 
  the 
  world 
  and 
  

   with 
  very 
  satisfactory 
  results. 
  On 
  the 
  other 
  hand 
  the 
  use 
  of 
  con- 
  

   crete 
  for 
  monolithic 
  construction 
  in 
  masonry, 
  arch 
  bridges, 
  tun- 
  

   nels 
  and 
  sewers 
  has 
  been 
  much 
  less 
  exploited 
  here 
  than 
  abroad. 
  

   The 
  best 
  work 
  in 
  massive 
  concrete 
  construction 
  is 
  probably 
  that 
  

   which 
  has 
  been 
  done 
  in 
  New 
  York 
  harbor, 
  where 
  large 
  monoliths 
  

   have 
  been 
  made 
  by 
  the 
  New 
  York 
  department 
  of 
  docks. 
  These 
  

   blocks 
  are 
  not 
  made 
  in 
  situ 
  but 
  are 
  prepared 
  in 
  large 
  timber 
  

   forms 
  and 
  allowed 
  several 
  weeks' 
  or 
  months' 
  hardening 
  in 
  the 
  

   air 
  before 
  being 
  placed 
  in 
  dock 
  and 
  bulkhead 
  walls. 
  Blocks 
  of 
  

   this 
  kind 
  made 
  by 
  the 
  New 
  York 
  department 
  of 
  docks 
  weigh 
  as 
  

   much 
  as 
  65 
  to 
  70 
  tons 
  and 
  have 
  proved 
  a 
  very 
  satisfactory 
  type 
  

   of 
  construction. 
  

  

  The 
  work 
  which 
  has 
  been 
  done 
  on 
  the 
  Wallabout 
  channel 
  in 
  

   Brooklyn 
  is 
  also 
  a 
  notable 
  and 
  successful 
  use 
  of 
  monolithic 
  con- 
  

   crete 
  masonry 
  for 
  this 
  purpose. 
  In 
  this 
  work 
  the 
  concrete 
  was 
  

   deposited 
  in 
  situ 
  but 
  as 
  the 
  water 
  was 
  excluded 
  by 
  coffer 
  dams 
  

   the 
  concrete 
  had 
  some 
  months' 
  hardening 
  in 
  the 
  air 
  before 
  being 
  

   subjected 
  to 
  the 
  action 
  of 
  the 
  salt 
  water. 
  

  

  Some 
  few 
  bridges 
  have 
  been 
  built 
  in 
  concrete 
  arches, 
  the 
  most 
  

   considerable 
  work 
  in 
  this 
  line 
  having 
  been 
  done 
  in 
  what 
  is 
  known 
  

   as 
  a 
  Melan 
  arch 
  construction, 
  in 
  which 
  steel 
  beams 
  are 
  bedded 
  in 
  

   massive 
  concrete. 
  

  

  A 
  use 
  of 
  hydraulic 
  cement 
  which 
  promises 
  a 
  great 
  develop- 
  

   ment 
  and 
  probably 
  a 
  unique 
  development 
  here 
  is 
  in 
  floor 
  arches 
  

   in 
  fire-proof 
  construction. 
  A 
  great 
  deal 
  of 
  work 
  of 
  this 
  kind 
  has 
  

   been 
  done 
  in 
  the 
  larger 
  cities 
  within 
  the 
  last 
  few 
  years, 
  and 
  some 
  

  

  