Anyone concerned with navigation, be he practising navigator, design or development engineer, teacher, or amateur yachtsman, will be aware that the great majority of developments took place prior to Captain Cook's epic voyages (1768–1779) or after 1904 when the first radio time signals were transmitted. During the first period the science of astro-navigation had been developed and such aids as log, chronometer, sextant andNautical Almanacwere available. The methods developed during that period differ very little from the traditional methods which are still in use today.