Abstract: Document detector and collector for detecting and collecting identifiable documents from a high speed stream of documents. A plurality of documents including identifiable documents are fed along a path. A detector detects the identifiable documents. A table is mounted above the document path to receive the identifiable documents. A first vacuum wheel responsive to the detector, removes the identifiable documents and feeds the removed documents to a second vacuum wheel. The second vacuum wheel delivers the documents to the delivery table.

Abstract: A low reflection coating for windows. A coating of silicone rubber is applied on one surface of the window and preferably also on the other surface. Each coating preferably has a thickness of several wavelengths of light and has a minimum thickness of two microns. The coating is low cost and is suitable for large areas, for instance solar heat collectors. Reflectivity is reduced by approximately one-third. The coating has no relation to a quarter wavelength or any multiple thereof of incident light.

Abstract: A heat storage tank suitable for solar house heating systems. The tank includes a rigidly supported bottom panel covered with a layer of stones of substantially uniform size which are bonded together thermally and mechanically at their points of contact with each other, but which have voids forming air passages remaining between them, bottom insulation below said bottom panel, a bottom air passage between the bottom insulation and the bottom panel, and at least one opening in the bottom panel whereby air can pass from said bottom air passage into said layer of stones.

Abstract: A solar heating system. A roof mounted panel collects heat from the sun. The panel having an upper sunlight-absorbing surface. A translucent cover is mounted above the panel to protect it from the weather. The panel has a lower surface for heat transfer to a stream of water. The panel is mounted in cooperative relation with a roof to form a passage for the stream of water. Means are connected to the panel for maintaining the stream of water in substantially uniform contact with said lower surface of the panel. Insulated tank means connected for receiving and storing the stream of water. Means are provided for controlling the stream of water under the panel in response to the temperature of the panel and the water in the tank, whereby the water collects heat from the panel only at useful temperatures. Air stream means are provided for preventing the roof from overheating.