﻿APPENDIX 
  

  

  CONSTRUCTION 
  AND 
  USES 
  OF 
  GOVERNMENT 
  CONTOUR 
  

  

  MAPS 
  

  

  A 
  number 
  of 
  plates, 
  comprising 
  portions 
  of 
  government 
  topo- 
  

   graphic 
  (contour) 
  maps, 
  have 
  been 
  introduced 
  into 
  this 
  book 
  for 
  

   the 
  purpose 
  of 
  illustrating 
  the 
  typical 
  relief 
  features 
  of 
  various 
  

   parts 
  of 
  the 
  State. 
  Since 
  many 
  persons 
  are 
  not 
  familiar 
  with 
  these 
  

   maps 
  and 
  their 
  uses, 
  a 
  brief 
  explanation 
  is 
  here 
  given. 
  

  

  These 
  topographic 
  maps, 
  which 
  are 
  called 
  sheets 
  or 
  quadrangles, 
  

   are 
  rectangular 
  in 
  shape 
  and 
  bounded 
  by 
  latitude 
  and 
  longitude 
  

   lines. 
  The 
  size 
  of 
  each 
  map 
  is 
  about 
  ijy 
  2 
  inches 
  high 
  by 
  11J/2 
  to 
  

   16 
  inches 
  wide, 
  the 
  latter 
  varying 
  with 
  the 
  latitude. 
  In 
  New 
  York 
  

   State 
  the 
  scale 
  is 
  nearly 
  always 
  1 
  to 
  62,500 
  or 
  nearly 
  one 
  mile 
  to 
  

   the 
  inch, 
  such 
  a 
  sheet 
  or 
  quadrangle 
  covering 
  an 
  area 
  of 
  just 
  one- 
  

   sixteenth 
  of 
  a 
  square 
  degree. 
  The 
  most 
  valuable 
  feature 
  of 
  these 
  

   maps 
  is 
  the 
  fact 
  that 
  the 
  surface 
  configuration 
  (relief) 
  of 
  the 
  

   country 
  is 
  so 
  accurately 
  shown, 
  this 
  feature 
  being 
  explained 
  by 
  the 
  

   accompanying 
  figures 
  and 
  the 
  following 
  description 
  which 
  is 
  gen- 
  

   erally 
  found 
  printed 
  on 
  the 
  back 
  of 
  each 
  map 
  : 
  " 
  Relief 
  is 
  shown 
  

   by 
  contour 
  lines 
  in 
  brown. 
  Each 
  contour 
  passes 
  through 
  points 
  

   which 
  have 
  the 
  same 
  altitude. 
  One 
  who' 
  follows 
  a 
  contour 
  on 
  the 
  

   ground 
  will 
  go 
  neither 
  up 
  hill 
  nor 
  down 
  hill, 
  but 
  on 
  a 
  level. 
  By 
  

   the 
  use 
  of 
  the 
  contours 
  not 
  only 
  are 
  the 
  shapes 
  of 
  the 
  plains, 
  hills, 
  

   and 
  mountains 
  shown, 
  but 
  also 
  the 
  elevations. 
  The 
  line 
  of 
  the 
  sea 
  

   coast 
  itself 
  is 
  a 
  contour 
  line, 
  the 
  datum 
  or 
  zero 
  of 
  elevation 
  being 
  

   the 
  mean 
  sea 
  level. 
  The 
  contour 
  line 
  at, 
  say, 
  20 
  feet 
  above 
  sea 
  

   level 
  is 
  the 
  line 
  that 
  would 
  be 
  the 
  sea 
  coast 
  if 
  the 
  sea 
  were 
  to 
  rise 
  

   or 
  the 
  land 
  to 
  sink 
  20 
  feet. 
  Such 
  a 
  line 
  runs 
  back 
  into 
  the 
  valleys 
  

   and 
  forward 
  around 
  the 
  points 
  of 
  hills 
  and 
  spurs. 
  On 
  a 
  gentle 
  

   slope 
  this 
  contour 
  line 
  is 
  far 
  from 
  the 
  present 
  coast 
  line, 
  while 
  on 
  

   a 
  steep 
  slope 
  it 
  is 
  near 
  it. 
  Thus 
  a 
  succession 
  of 
  these 
  contour 
  lines 
  

   far 
  apart 
  on 
  the 
  map 
  indicates 
  a 
  gentle 
  slope 
  ; 
  if 
  close 
  together, 
  a 
  

   steep 
  slope; 
  and 
  if 
  the 
  contours 
  run 
  together 
  in 
  one 
  line, 
  as 
  if 
  each 
  

   were 
  vertically 
  under 
  the 
  one 
  above 
  it, 
  they 
  indicate 
  a 
  cliff. 
  . 
  . 
  . 
  

   The 
  contour 
  interval, 
  or 
  vertical 
  distance 
  in 
  feet 
  between 
  one 
  

   contour 
  and 
  the 
  next, 
  is 
  stated 
  at 
  the 
  bottom 
  of 
  each 
  map. 
  This 
  

   interval 
  varies 
  according 
  to 
  the 
  character 
  of 
  the 
  area 
  mapped; 
  in 
  a 
  

   flat 
  country 
  it 
  may 
  be 
  as 
  small 
  as 
  5 
  feet; 
  in 
  a 
  mountainous 
  region 
  

   it 
  may 
  be 
  200 
  feet. 
  Certain 
  contours, 
  usually 
  every 
  fifth 
  one, 
  are 
  

  

  [118] 
  

  

  