The automatic control of the spectrographic exposure

An electronic circuit is described by which the following cycle of operations automatically occurs on initiation; the pre-spark starts, the spectrograph shutter opens after a fixed time, the plate remains exposed for the required period, then the shutter closes just prior to switching off the spark and finally the apparatus is reset. By choosing suitable values of the components, a multi-position selector switch enables a choice of pre-spark and the exposure times to be made. It is claimed that this device eliminates some of the tedium of routine spectrograph analysis, saves the operator's time and eliminates some of the personal error.