Deck Prism
Historically, on old sailing vessels, prisms were employed to redirect sunlight to areas below deck where natural light was scarce. These regions, typically devoid of sunlight, were illuminated using prisms as a safer alternative to oil lamps, kerosene lanterns, and candles. Due to their enhanced safety features, prisms were the preferred choice for illuminating the decks of sailing vessels.
According to historical records, it is believed that the use of deck prisms on ships became prevalent around the 1840s. However, there is ongoing debate as some argue that their usage may have begun centuries earlier.
The deck prism shared several important features:
- Construction: Typically made of glass, the deck prism resembled a conventional prism in shape and material.
- Mounting: Deck prisms were installed on ship roofs or held in place by a specific device to maximize sunlight reflection.
- Multiplicity: Some sailing vessels had multiple deck prisms mounted to ensure better lighting below deck.
- Design: Deck prisms were flat-bottomed, facilitating easy mounting. They tapered towards the top and featured multiple faces to enhance the reflection of light. While most prisms were orbital and flat-bottomed, rectangular flat-bottomed prisms were also used. The renowned American whaling vessel Charles W. Morgan, operational in the early 1840s and currently displayed at the Mystic Seaport museum, had a notable prism installation.
- Functionality: Deck prisms were not only used on general vessels but also on those transporting coal. The reflected light from the prism indicated the quantity of coal cargo present in the ship.
Many maritime museums house artifacts related to deck prisms, preserving their historical significance. Despite the convenience of modern electronic lighting, these remnants of the past hold a unique place in maritime history. Hence, some vessels still choose to affix deck prisms, allowing individuals to reconnect with this valuable aspect of maritime heritage.