Abstract: A book light that is removably mounted to a book spine, has a flexible lamp support arm, and provides a rotational device that enables full 360 degree rotation of the lamp support arm about a longitudinal axis of the book spine such that a reader can comfortably hold and read a paperback book folded back upon itself with one hand, a page facing the reader is well illuminated, and subsequent pages can be illuminated by turning the folded book over to a new page and simply rotating the lamp support arm and lamp over the new reading page, all without having to remove and re-mount the book light from the book.

Abstract: A leak detection system for detecting a fuel leak from a storage tank comsing a vertically positioned reference tube that spans the full useful length of the fuel tank which is generally located underground. The reference tube is filled and drained with the tank. The system also has a normally open pneumatic by-pass valve which when closed isolates the reference tube from the tank. A differential pressure gauge between the tank and reference tube reads zero pressure immediately after closure of the by-pass valve. A differential pressure reading between the tank and reference tube indicates the presence of fuel leakage from the tank. The inside of the reference tube is tapered at the top portion and bottom portion of the tube to match the cross sectional area of the tank upper dome and lower tank dome ends, while the outside diameter of the tube remains constant through out the length of the tube.