Brief description

A diving bell is a heavy, bell-shaped chamber that is open at the bottom and lowered into the water to allow divers to work underwater. It traps a pocket of air at the top, providing a dry environment and a breathable atmosphere for a limited time or through a continuous supply.

Use / Function

• Primary use: Underwater salvage, construction (foundations for bridges and lighthouses), and exploration.
• Secondary uses: Gathering food (shellfish), repairing ship hulls, and recovery of lost treasures.
• Scale: Local (underwater work sites).

Operating principle

Air Displacement and Pressure:

1. Trapped Air: When the bell is lowered vertically into the water, the air inside is trapped because it is less dense than water and has no way to escape through the solid top or sides.
2. Pressure Balance: As the bell goes deeper, the water pressure increases, which compresses the air inside. The water level inside the bell rises slightly, but the air pocket remains.
3. Breathable Atmosphere: The diver breathes the trapped air. For longer durations, fresh air must be pumped down from the surface via a hose or delivered in weighted barrels.

How to create it

1. The Chamber

• Construct a sturdy, watertight container in the shape of a bell or a barrel.
• Use Wood staves reinforced with Iron hoops, or cast it entirely from iron for greater strength and natural weight.
• Ensure the top and sides are completely airtight.

2. Weighting

• The bell must be heavier than the water it displaces to sink.
• Attach heavy weights (lead or iron) to the bottom rim to ensure it remains upright and stable during descent.

3. Interior Setup

• Install a bench or platform for the diver to sit on above the water line.
• Add hooks for tools and a way to signal the surface (like a rope or a bell).

4. Viewing Port (Optional)

• Cut a small hole and seal it with thick Glass and Leather gaskets to allow the diver to see outside.

Materials needed

• Essential materials: Iron (for the frame and weights), Wood (for the structure), Rope (for lowering and signaling).
• Tools: Hammers, saws, forging tools for iron hoops.
• Possible substitutes: Large barrels or casks can be modified for shallow water use.

Variants and improvements

• Air Resupply: Using a Bellows and a leather Hose to pump fresh air into the bell from the surface, allowing for indefinite stays.
• Weighted Barrels: Lowering separate barrels of fresh air that are then opened inside the bell.
• Diving Suit: A later advancement that allows the diver to move independently of the bell, connected only by an air line.

Limits and risks

• Air Quality: Carbon dioxide builds up as the diver breathes. Without fresh air, the diver will suffocate.
• The Bends (Decompression Sickness): When rising from great depths, nitrogen dissolved in the blood can form bubbles if the ascent is too fast, causing severe pain or death.
• Instability: If the bell tips, the air pocket will escape, and the bell will immediately flood.
• Pressure: At great depths, the pressure can be physically taxing or even crush a poorly constructed chamber.