Glossary - Part H

•  Harbor Light: A light to guide ships safely into a harbor. This is usually a small light at the end of a pier.

•  Hazard Avoidance Light: A lighthouse used to mark a specific hazard such as a shoal, reef, rocky point or dangerous island.

•  Holophotal System: In 1849, Thomas Stevenson of Scotland invented a new reflector design where no light escapes around the rim of the reflector as was the case in all other reflector designs.

•  Horn: A sound signal, which uses electricity or compressed air to vibrate a disc diaphragm.