A steelyard balance, steelyard, or stilyard is a straight-beam balance with arms of unequal length. It incorporates a counterweight which slides along the longer arm to counterbalance the load and indicate its weight. A steelyard is also known as a Roman steelyard or Roman balance.

What is a steelyard used for?

Steelyards of different sizes have been used to weigh loads ranging from ounces to tons. A small steelyard could be a foot or less in length and thus conveniently used as a portable device that merchants and traders could use to weigh small ounce-sized items of merchandise.

How does a steelyard work?

The steelyard balance has been around since ancient times. It works by employing a counterweight and lever to weigh objects. Leverage is adjusted by sliding the counterweight on a metal arm. The balance may be used to demonstrate the principles of torque and center of mass.