Definition of "quadrat":
Quadrat
(n.) A block of type metal lower than the letters, -- used in spacing and in blank lines.
(n.) An old instrument used for taking altitudes; -- called also geometrical square, and line of shadows.

I found a glossary of printing terms, but it didn't have "chase":
http://home.vicnet.net.au/~typo/glossary/theme-h.htm