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Steelyard balance

Steelyard balance is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Steelyard balance rather than just read about it. In short: 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.

Steelyard balance — main illustration
Steelyard balance — illustration

Key takeaways

  • Steelyard balance belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Steelyard balance to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Steelyard balance from memory before moving on to harder problems.

Reference excerpt

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.

Structure

The steelyard comprises a balance beam which is suspended from a lever/pivot or fulcrum which is very close to one end of the beam. The two parts of the beam which flank the pivot are the arms. The arm from which the object to be weighed (the load) is hung is short and is located close to the pivot point. The other arm is longer, is graduated and incorporates a counterweight which can be moved along the arm until the two arms are balanced about the pivot, at which time the weight of the load is indicated by the position of the counterweight.

Mechanism The steelyard exemplifies the law of the lever, wherein, when balanced, the net moment around the pivot must be zero. Since M = F d {\displaystyle M=Fd} , the weight of the object being weighed multiplied by the length of the short balance arm to which it is attached is equal to the weight of the counterweight multiplied by the distance of the counterweight from the pivot.

History According to Thomas G. Chondros of Patras University, a simple steelyard balance with a lever mechanism first appeared in the ancient Near East over 5,000 years ago. According to Mark Sky of Harvard University, the steelyard was in use among Greek craftsmen of the 5th and 4th centuries BC, even before Archimedes demonstrated the law of the lever theoretically. The Latin name statera comes from the Ancient Greek στατήρ (statḗr). Roman and Chinese steelyards were independently invented around 200 BC. Steelyards dating from AD 100 to 400 have been unearthed in Great Britain. Steelyards and their components have also been excavated from shipwrecks of the Byzantine period in the Mediterranean and the Red Sea, such as the 7th-century wreck at Yassi Ada, Turkey, and the mid-first millennium shipwreck at Black Assarca Island, Eritrea. The Oxford English Dictionary suggests that the name "steelyard" is derived from steel combined with yard, influenced by an allusion to the Steelyard, the main trading base of the Hanseatic League in London in the 14th century.

Large steelyard balances (known as cart steelyards), both public and private, were a common feature in agricultural areas in England from the eighteenth century forward. An example of a public cart steelyard remains at Soham, Cambridgeshire, and another is at Woodbridge, Suffolk.

Function 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. Small steelyard-type rocker balances were also made to weigh and gauge coins. An English example made around 1840, Simmons's Improved Sovereign Balance, was designed for sovereigns and half-sovereigns and checked both their diameter and thickness. In other cases a steelyard could be several feet long and used to weigh sacks of flour and other commodities. Even larger steelyards were three stories tall and used to weigh fully laden horse-drawn waggons.

Electromagnetic steelyard balance A steelyard could be used to measure electric current. in 1856 Wildman Whitehouse announced his method of using magnetic coils, representing the load be measured, at one end of a steelyard balance. The position of the moving weight on the balance was adjusted in the usual way to counter the pull of the coils. Whitehouse claimed that his invention gave a steadier reading of current passing through telegraph cables under test than the galvanometers then commonly used.

Horizontal variants

A horizontal cart balance or cart steelyard has grooved plates, mounted on pivoted frames, to receive the wheels of a cart. The movement of the frames is transferred to a conventional steelyard, mounted on a post, by a horizontal chain. In 1870, a patent was granted to the North British Railway for a similar apparatus to weigh railway waggons. A printed paper chart is mounted behind the steelyard weight, which has a pin attached. When the waggon is in place the pin is made to strike the chart, providing an automatic record of the weight.

Scandinavian variant A Scandinavian steelyard is a variant which consists of a bar with a fixed weight attached to one end, a movable pivot point, and an attachment point for the object to be weighed at the other end. Once the object to be weighed is attached to its end of the bar, the pivot point, which is frequently a loop at the end of a cord or chain, is moved until the bar is balanced. The bar is calibrated so that the object's weight can be read off directly from the position of the pivot. This type is known in Sweden, Denmark, Norway and Finland

Gallery

See also Weigh house

References

External links

The physics of the steelyard To calibrate a steelyard Roman steelyard and weight from Caernarfon Iron steelyard Steelyard with sliding weight Steelyard Weight and Hook A Roman steelyard, 79 AD The Chinese steelyard dates to 200 B.C.E. Roman steelyards unearthed in Britain A three-storey steelyard

Illustrations

Steelyard balance: A 19th-century steelyard crane
A 19th-century steelyard crane
Steelyard balance: Steelyard weighing device from the late nineteenth century. Minnesota Historical Society collections.
Steelyard weighing device from the late nineteenth century. Minnesota Historical Society collections.
Steelyard balance: Roman steelyard from Pompeii
Roman steelyard from Pompeii
Steelyard balance: Eighteenth century cart balance at Fountains Lane, Soham
Eighteenth century cart balance at Fountains Lane, Soham
Steelyard balance: Waybill for consignment of limestone, weighed on a wagon steelyard of the North British Railway
Waybill for consignment of limestone, weighed on a wagon steelyard of the North British Railway

Worked examples

Example 1 — a first encounter with Steelyard balance

Start with the simplest possible case. Write down what Steelyard balance claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Steelyard balance before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Steelyard balance ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Steelyard balance

In research
Steelyard balance appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Steelyard balance in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Steelyard balance is common in secondary-school and first-year university syllabi. It links to neighbouring topics Weighing instruments, so understanding it makes those chapters shorter.
In everyday life
Look for Steelyard balance outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Steelyard balance in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Steelyard balance means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Steelyard balance out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Steelyard balance in simple terms?

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.

Why does Steelyard balance matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Steelyard balance?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Steelyard balance.

Tags

  • Weighing instruments

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