Historical clue formulations

• Lighthouse light — 2019-04-08
• High light? — 2016-03-24
• The Bat-Signal, e.g. — 2015-08-13
• Source of hope? — 2004-10-07
• Fire sign — 2003-04-04
• Mariner's aid — 1997-09-10
• Lighthouse light — 1996-12-30
• Naval guide — 1995-08-02
• Guiding light — 1995-01-31