﻿758 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  TEKRA 
  GOTTA 
  

   General 
  properties 
  

  

  The 
  increasing 
  tendency 
  of 
  architects 
  to 
  place 
  considerable 
  adorn- 
  

   ment 
  on 
  the 
  exterior 
  of 
  buildings 
  has 
  led 
  to 
  the 
  extensive 
  adoption 
  

   of 
  terra 
  cotta 
  as 
  a 
  cheap 
  substitute 
  for 
  stone. 
  

  

  The 
  advantages 
  ascribed 
  to 
  it 
  are 
  

   Durability 
  

   Cheapness 
  

   Permanent 
  color 
  

   Resistance 
  to 
  fire 
  

   Lightness 
  and 
  strength. 
  

  

  The 
  term 
  terra 
  cotta 
  is 
  usually 
  applied 
  to 
  those 
  ornamental 
  clay 
  

   products 
  for 
  structural 
  work 
  which 
  are 
  more 
  than 
  8 
  inches 
  square^ 
  

   If 
  the 
  pieces 
  are 
  under 
  this 
  size 
  they 
  are 
  called 
  ornamental 
  brick. 
  

  

  Terra 
  cotta 
  objects 
  should 
  be 
  burned 
  to 
  an 
  even 
  color, 
  the 
  pieces 
  

   should 
  be 
  of 
  regular 
  outline 
  and 
  not 
  show 
  signs 
  of 
  warping, 
  neither 
  

   should 
  they 
  discolor 
  superficially. 
  The 
  hardness 
  should 
  be 
  above 
  

   6 
  in 
  the 
  scale, 
  that 
  is, 
  it 
  should 
  resist 
  scratching 
  with 
  a 
  knife. 
  

  

  Terra 
  cotta 
  is 
  seldom 
  vitrified, 
  but 
  the 
  slip 
  covering 
  the 
  surface 
  

   generally 
  forms 
  an 
  impervious 
  coating, 
  and 
  also 
  serves 
  to 
  give 
  the 
  

   desired 
  color 
  to 
  the 
  ware. 
  

  

  At 
  first 
  the 
  forms 
  produced 
  in 
  terra 
  cotta 
  were 
  comparatively 
  

   simple, 
  but 
  improvements 
  in 
  methods 
  and 
  experience 
  have 
  greatly 
  

   extended 
  the 
  possibilities 
  of 
  the 
  material. 
  Among 
  the 
  more 
  re^ 
  

   cent 
  uses 
  is 
  to 
  be 
  mentioned 
  its 
  employment 
  in 
  columns 
  and 
  balus- 
  

   trades. 
  

  

  In 
  the 
  manufacture 
  of 
  balustrades 
  the 
  solids 
  and 
  voids 
  should 
  be 
  

   made 
  in 
  the 
  proper 
  proportions 
  to 
  prevent 
  warping 
  and 
  cracking 
  

   of 
  the 
  ware 
  in 
  burning. 
  

  

  The 
  strength 
  of 
  terra 
  cotta 
  brackets 
  has 
  been 
  well 
  shown 
  by 
  the 
  

   following 
  experiments:* 
  

  

  ^ 
  An 
  important 
  and 
  instructive 
  series 
  of 
  articles 
  on 
  "Terra 
  cotta 
  in 
  archi- 
  

   tecture", 
  by 
  T. 
  Cusack, 
  has 
  appeared 
  in 
  the 
  Brickhuilder. 
  1898. 
  p. 
  7, 
  55, 
  98, 
  

   142, 
  185, 
  230. 
  

  

  