﻿I08 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  ered 
  steel 
  die 
  of 
  circular 
  section, 
  about 
  i 
  i^ 
  in. 
  diameter, 
  mixed 
  with 
  

   water, 
  and 
  subjected 
  to 
  a 
  pressure 
  of 
  2,300 
  kilograms 
  (about 
  3 
  tons). 
  

   The 
  resulting 
  briquette 
  is 
  then 
  put 
  aside 
  for 
  at 
  least 
  one 
  week, 
  so 
  that 
  it 
  

   may 
  thoroughly 
  dry. 
  

  

  It 
  was 
  at 
  first 
  thought 
  that 
  a 
  test 
  by 
  direct 
  compression 
  would 
  deter- 
  

   mine 
  the 
  cementing 
  power 
  of 
  the 
  stone. 
  A 
  number 
  of 
  briquettes 
  were 
  

   tried 
  in 
  this 
  way, 
  but 
  the 
  results 
  were 
  not 
  very 
  satisfactory. 
  On 
  further 
  

   consideration, 
  it 
  appears 
  that 
  a 
  test 
  by 
  impact 
  would 
  more 
  thoroughly 
  

   determine 
  the 
  cementing 
  power 
  of 
  the 
  stone 
  then 
  that 
  by 
  compression, 
  

   and 
  this 
  method 
  would 
  have 
  the 
  further 
  advantage 
  of 
  approximating 
  

   more 
  closely 
  to 
  the 
  actual 
  conditions 
  obtaining 
  on 
  roads 
  ; 
  accordingly 
  a 
  

   machine 
  was 
  devised 
  for 
  testing 
  the 
  briquettes 
  by 
  impact. 
  With 
  this 
  

   machine 
  a 
  hammer 
  one 
  kilogram 
  (2 
  2-3 
  lbs) 
  in 
  weight 
  can 
  be 
  dropped 
  

   freely 
  from 
  any 
  desired 
  height 
  upon 
  a 
  plunger 
  under 
  which 
  the 
  briquette 
  

   to 
  be 
  tested 
  is 
  placed. 
  The 
  hammer 
  works 
  automatically 
  and 
  is 
  tripped 
  

   at 
  the 
  desired 
  height. 
  Attached 
  to 
  the 
  plunger 
  is 
  a 
  lever, 
  pivoted 
  at 
  one 
  

   sixth 
  of 
  its 
  length 
  from 
  the 
  plunger, 
  and 
  carrying 
  a 
  pencil 
  at 
  its 
  free 
  end. 
  

   The 
  pencil 
  has 
  a 
  vertical 
  movement 
  five 
  times 
  as 
  great 
  as 
  that 
  of 
  the 
  

   plunger, 
  audits 
  movement 
  is 
  registered 
  on 
  a 
  drum 
  against 
  which 
  the 
  

   pencil 
  presses. 
  The 
  drum 
  rotates 
  through 
  a 
  small 
  angle 
  at 
  each 
  stroke 
  

   of 
  the 
  hammer. 
  An 
  automatic 
  diagram 
  is 
  thus 
  taken 
  of 
  the 
  behavior 
  

   of 
  the 
  briquette 
  throughout 
  the 
  whole 
  test. 
  

  

  An 
  analysis 
  of 
  the 
  diagram 
  so 
  taken 
  shows 
  at 
  once 
  the 
  number 
  of 
  blows 
  

   required 
  to 
  cause 
  the 
  destruction 
  of 
  the 
  briquette. 
  A 
  very 
  interesting 
  

   point 
  is 
  brought 
  out 
  by 
  these 
  diagrams, 
  viz, 
  in 
  every 
  case 
  the 
  diagram 
  

   shows 
  that 
  the 
  plunger 
  rebounded 
  at 
  each 
  stroke 
  until 
  the 
  briquette 
  began 
  

   to 
  fail. 
  This 
  behavior 
  is 
  exactly 
  analogous 
  to 
  the 
  elastic 
  phenomena 
  ob- 
  

   served 
  in 
  all 
  material 
  of 
  construction; 
  consequently 
  the 
  point 
  at 
  which 
  

   the 
  briquette 
  ceases 
  to 
  rebound 
  corresponds 
  to 
  the 
  elastic 
  limit 
  of 
  the 
  

   material. 
  Beyond 
  this 
  point 
  the 
  briquette 
  falls 
  to 
  pieces 
  rapidly. 
  

  

  Briquettes 
  were 
  made 
  from 
  many 
  kinds 
  of 
  stone, 
  and 
  were 
  tested 
  in 
  

   this 
  machine. 
  It 
  was 
  thought 
  desirable 
  to 
  use 
  a 
  constant 
  blow 
  for 
  all 
  

   the 
  briquettes, 
  and 
  a 
  short 
  experience 
  indicated 
  a 
  fall 
  of 
  1 
  1^ 
  in. 
  as 
  suitable, 
  

   since 
  it 
  broke 
  the 
  most 
  tenacious 
  materials 
  with 
  a 
  moderate 
  number 
  of 
  

   blows, 
  and 
  yet 
  was 
  not 
  too 
  great 
  to 
  permit 
  the 
  careful 
  determination 
  of 
  

   the 
  properties 
  of 
  the 
  poorer 
  stones. 
  All 
  the 
  briquettes 
  were 
  i 
  in. 
  

   high. 
  

  

  The 
  surface 
  of 
  a 
  macadamized 
  road 
  is 
  constantly 
  being 
  abraded 
  and 
  

   recemented. 
  Evidently 
  a 
  road 
  made 
  from 
  a 
  material 
  which 
  has 
  the 
  

   property 
  of 
  recementing 
  in 
  a 
  high 
  degree 
  will 
  keep 
  in 
  better 
  condition 
  

   than 
  one 
  made 
  from 
  a 
  material 
  of 
  lower 
  recementing 
  power. 
  It 
  was 
  

   therefore 
  desirable 
  to 
  determine 
  the 
  recementing 
  properties 
  of 
  the 
  stones 
  

   tested. 
  A 
  new 
  set 
  of 
  briquettes 
  was 
  made, 
  differing 
  from 
  the 
  former 
  

   only 
  in 
  that 
  they 
  were 
  of 
  constant 
  weight 
  instead 
  of 
  constant 
  height. 
  

   These 
  were 
  tested 
  in 
  the 
  manner 
  described 
  above, 
  and 
  then 
  were 
  remade 
  

   and 
  retested. 
  

  

  It 
  has 
  not 
  been 
  thought 
  desirable 
  to 
  present 
  herewith 
  the 
  complete 
  data 
  

   obtained 
  from 
  the 
  impact 
  test: 
  as 
  the 
  series 
  is 
  not 
  yet 
  completed. 
  The 
  

   writer 
  has, 
  however, 
  collected 
  and 
  shown 
  in 
  the 
  accompanying 
  table 
  

   some 
  of 
  the 
  more 
  important 
  results 
  thus 
  far 
  obtained, 
  a 
  sufhcient 
  number 
  

   to 
  indicate 
  the 
  scope 
  of 
  the 
  work 
  done. 
  In 
  this 
  table 
  the 
  stones 
  are 
  

   arranged 
  in 
  the 
  order 
  of 
  their 
  power 
  of 
  resisting 
  abrasion. 
  Column 
  i 
  

  

  