Elizabeth Speakman O'Neill, 1911 Encyclopædia Britannica, Volume 28… (1911)
“ Vicars-apostolic at the present day are nearly always titular bishops taking their titles from places not acknowledging allegiance to the Roman Catholic Church. The title is generally given by the pope to bishops sent on Eastern missions. A neighbouring bishop was sometimes appointed by the pope vicar of a church which happened to be without a pastor. A special vicar was appointed by the pope to superintend the spiritual affairs of Rome and its suburbs, to visit its churches, monasteries, &c., and to correct abuses. ”
