Granted Patent
Utility
US 4,404,955 · App. 06/294,614
Fireplace heat extractor
Inventors:
William P. Sherman, Floyd R. Clark, Lothar K. Will
Patented Case
View Patent ↗
Granted: Sep 20, 1983
Filed: Aug 20, 1981
Inventors
William P. Sherman
Floyd R. Clark
Lothar K. Will
Assignee (at issue)
THOMAS INDUSTRIES, INC.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.