Abstract: A telephone directory having a plurality of pages is disclosed. The pages can be moveable between a first position and a second position such that a desired page can be selected by moving pages from the first position to the second position until the desired page is at the top of a stack of pages in the first position. Each page can comprise locations for a plurality of photographs. Selectors can be provided for selecting one of the photograph locations on the selected page. Telephone numbers of persons or places depicted in photographs on the pages can be stored in a digital memory. A telephone call can be initiated to a particular person or place by selecting the page and photograph location on the page of that person or place.

Abstract: Energy beams with different wavelengths or wavelength ranges may be passed through a gas sample in a test chamber. Ones of the energy beams may have wavelengths or wavelength ranges that are absorbed by particular gases. To determine whether any of those particular gases are in the gas sample, the loss of energy, if any, as the beams pass through the gas ample may be determined. The presence of one or more gases that do not absorb the energy beams may be determined by placing a chemical reactant that reacts with those one or more gases and then detecting a chemical reaction between the chemical reactant and the gas sample.

Abstract: A telephone directory having a plurality of pages is disclosed. The pages can be moveable between a first position and a second position such that a desired page can be selected by moving pages from the first position to the second position until the desired page is at the top of a stack of pages in the first position. Each page can comprise locations for a plurality of photographs. Selectors can be provided for selecting one of the photograph locations on the selected page. Telephone numbers of persons or places depicted in photographs on the pages can be stored in a digital memory. A telephone call can be initiated to a particular person or place by selecting the page and photograph location on the page of that person or place.