Pat,
 
Funny you should mention this, as we just recovered a 1910 advertisement  for 
a Prairie style building in San Diego that advertised the chimney as having  
"Dutch clinker bricks" in the chimney. This is a chimney of sandy common 
bricks  with a diamond pattern comprised of dark over-fired (distorted and bubbly)  
bricks set slightly out from the rest of the bricks. When you stand away from 
 the building, the diamond pattern becomes evidence. When close, it cannot be 
 discerned. 
 
Ron May
Legacy 106, Inc.