A transition for IEP

An electronic sundial apparatus which signals the passage of each hour by a chime, bell or other audible indication and which requires no external source of power other than the sun. Inner and outer concentric hemispheres with vertically extending apertures, specifically slits, configured so as to diverge at their uppermost ends and having a location, length and shape corresponding to the azimuths and distance between the maximum and minimum altitudes of the sun in the sky at each hour throughout the year at predetermined latitudes collimate the sunlight once each hour. The collimated sunlight is detected by a photoelectric cell coupled to a signaling circuit powered by a photovoltaic cell.