Abstract: Permanent gray-scale reproductions including half-tone images. A refractory background region bears refractory thin-film dichroic filter means patterned to conform to the reproduced half-tone image. Preferred background region materials include metals, semiconductors, and ceramics; the thin-film materials are preferably oxides or nitrides of metals and semiconductors. If the refractory materials are appropriately selected, the reproductions are highly resistant to chemical and thermal deterioration and should have useful lives in the hundreds of thousands of years.

Abstract: A heating system includes a water heating solid fuel stove operated in conjunction with a gas or oil fired hot water furnace. The two are connected in parallel and furnish heat to at least one heating zone and domestic hot water. In a first embodiment, a circulator pump is coupled to receive zone return fluid at its inlet and pump fluid from its outlet to the fluid fuel fired and solid fuel fired boilers. A first water valve is coupled between the circulator outlet and the solid fuel fired boiler, and a second water valve is coupled between the circulator inlet and the solid fuel fired boiler. In a second embodiment, separate circulator pumps are coupled in series with each of the fluid fuel fired and solid fuel fired boilers.