Abstract: A book mark is disclosed which is an extension of a book's endpaper or flyleaf and folded such that the fold coincides with the width of the book page and the extension folds inwardly to mark a place in the book. The book mark may be made as a separate endpaper extension by folding a sheet of paper of defined length along its longitudinal axis to form a major portion and a minor portion which has adhered to its outfold surface adhesive for attachment to the endpaper or flyleaf such that the outer edge of the endpaper or flyleaf coincides with the fold and the extension folds inwardly to mark a place in the book.

Abstract: A conduit construction which enhances the flow of liquid to a turbine when the rate of flow from the liquid source is low, and which limits the flow to the turbine when the flow rate from the source is high. The turbine is placed in a branch conduit which communicates with the interior of a larger main conduit through an opening in the side of the main conduit near its bottom. A flow diverter in the form of a vertically concave wall extends from the downstream side of the opening across the bottom segment of the main conduit, curving upstream as it does so; the wall stops below the top of the interior of the main conduit, leaving room for liquid to flow over it. When the flow rate is small, the diverter collects all of the liquid stream in the main conduit and delivers it to the branch conduit; when the flow in the main conduit becomes excessively high, it flows in part over the diverter, thus mitigating the tendency for the liquid to back up in the main conduit.

Abstract: A hydroelectric generator is located in the basement of a high-rise building and connected in series in the clean waste-water line of the building, to produce electrical power in response to the flow of the waste water from the building. An automatically controlled valve in a bypass line serves to direct excess water flow around the hydroelectric generator unit and maintain the flow through the generator unit at a predetermined maximum level. An automatic switch-over device disconnects the generator output terminals from the electrical output terminals of the unit when the voltage and/or frequency of the generator output is unsatisfactory, e.g., too low.