Brief description

A device for measuring mass by comparing an object of unknown mass with an object of known mass.

Use / Function

• Trade: Weighing gold, Spices, food.
• Chemistry/Medicine: Measuring ingredients.

Operating principle

Leverage. A beam pivots at its center (fulcrum). Gravity acts on masses at both ends. When the beam is horizontal, the torque on both sides is equal. If arms are equal length, masses are equal.

How to create it

1. Beam: A straight, rigid stick or bone.
2. Fulcrum: Find the exact center of mass of the beam. Drill a hole or tie a string there.
3. Pans: Hang two identical lightweight containers from the ends of the beam, equidistant from the center.
4. Check: It must balance perfectly when empty. If not, shave weight off the heavier side.

Materials needed

• Essential: Straight Wood or bone beam, suspension cords from Plant fibers or Leather, matched pans of Clay, wood, or gourds.
• Tools: Knife, awl or drill, cord for hanging, reference weights or a known standard.
• Possible substitutes: Pebbles or seed weights for calibration, woven baskets instead of pans, braided fiber in place of leather.

Variants and improvements

• Steelyard Balance: Uses a fixed counterweight and a movable fulcrum (or movable weight on long arm) to measure variable masses with one weight.

Limits and risks

• Drafts: Wind or movement throws off readings.
• Calibration drift: Uneven wear or wet pans changes balance.
• Contamination: Wet goods or powders can stick and bias weights.
• Fragility: Thin beams or cords can snap under heavy loads.