Eighteenth Century Coin Weights and Counterfeit Coins

Earlier in 2020, the South and West Yorkshire PAS office recorded an interesting coin weight, SWYOR-80FFA8, which was probably made locally in Sheffield. In this blog, SWYOR volunteer Diane Gourley looks into the history and local connections to the manufacture of this object in a little more depth.

Underweight half guinea coin weight
SWYOR-80FFA8: a lightweight half guinea coin weight dating from 1773 – 1800. Copyright: West Yorkshire Archaeology Advisory Service, CC BY-SA

The post medieval coin weight SWYOR-80FFA8 is a copper alloy half guinea coin weight dating from 1773 – 1800. It is thought that it was either made by the firm of Charles and Luke Proctor in Sheffield or it is a copy of a design made by the firm.  It is seriously under the required mass and may have been made to carry out illegal activities. A coin weight of low mass would presumably persuade traders to accept coins that were below the legal minimum weight. You can see the full record for the weight on the PAS database here.

The inscription of “S d // 10 6 // Pw Gr // 2 16½” indicates that the weight was supposed to weigh two pennyweights and sixteen and a half grains, the lowest legal weight of a half guinea (a coin with the value of ten shillings and six pennies) from 1773 onwards. This equates to 4.2g, but SWYOR-80FFA8 is only 3.2g.

In the eighteenth century, counterfeit coins were a major concern because of the harm they did to business and trade. There were a variety of methods used to remove gold from genuine coins and this was widespread and common practice in some parts of the country. It was known to be carried out in Yorkshire at this time (and also see SWYOR-AEF0A6 and SWYOR-9E9B0E  for evidence of coin forgery in the seventeenth century in South Yorkshire). The pilfered gold was then used to make fake Portuguese coins, of types that were widely used in the United Kingdom

Removing gold from genuine coins

A number of techniques were used to supply counterfeiters with gold from genuine coins, including a method known as ‘sweating’ which consisted of rubbing coins together in a leather bag causing wear from which gold dust formed. Several bags could be strapped to the wheel of a wagon. Other methods were to clip or file the edges of coins. It could be difficult to detect by sight alone if thin slivers of gold had been carefully removed from the edges of coins. A variety of techniques were used to replace the milled edges of the coins. Sometimes gold was removed from genuine coins by immersing them in a mixture of acids. Gold was later recovered by a chemical process.

Methods used by counterfeiters

Counterfeiters used alloying to produce counterfeit coins. Clippings and gold dust were melted with silver to form an alloy. The hot metal was cast into small blank discs in a brass mould before being hammered to size. Next it was punched between dies to give the markings and appearance of a real coin. Sometimes gold was alloyed with copper but this was easier to detect as counterfeit coins of the same size as real coins were lighter in weight. Another method used by counterfeiters was to file two genuine coins so they were wafer thin and then to solder them to a disc of copper. The edges were gold-plated to hide the layers of different metals. Alternatively, complete copper discs were gold-plated by counterfeiters.

Counterfeiters’ success in producing fake coins lay in imitation coins being produced with great skill, and was further guaranteed by producing coins which the public were less familiar with, such as the coins from a previous monarch’s reign or the imported Portuguese currency which was in circulation in Britain. Ordinary citizens rarely handled gold coins, were unfamiliar with what a genuine coin should look like and did not possess a genuine coin for comparison.

Portuguese gold coin; a moeda, which would have circulated in Britain
SUR-422962: A Portuguese gold moeda coin, known in eighteenth century England as a moidore and widely accepted as currency in Britain. Copyright: Surrey County Council, CC BY-SA

The Recoinage of 1773-1776

The government, concerned about the widespread fake coinage circulating in Britain because of the effect this was having on business and trade, took steps to reduce the number of fake coins in circulation by bringing in a phased withdraw of underweight coins between 1773 and 1776.

The Light Coin Act of 1773 gave citizens the right to deface light coins offered to them. The phased withdrawal allowed fake coins above a certain weight to remain in circulation so that any effects of suddenly removing a lot of coins on which traders relied could be minimised.  Further coinage reforms were carried out in 1774 and 1776 until only guineas at the correct weight remained in circulation. 

Portuguese coins still formed a large part of the circulating currency though they were not mentioned in the re-coinage act, possibly because it was thought that removing fake guineas from circulation would make it more risky to hold Portuguese gold.  In 1773, tradesmen in different parts of the country advertised that they would accept light guineas and Portuguese gold because they feared loss of trade and there was an opportunity to profit as people with light guineas accepted discounted rates.  Businessmen could then sell a quantity of light guineas and Portuguese gold back to the Bank at a standard rate.  It is likely though, that Portuguese coins remained in circulation after 1775.

Weighing coins to spot fakes

Provision was made for light coins to be returned to the mint for re-coinage, however the measures taken were inadequate, and clipping, filing and counterfeiting continued.  Coin scales were produced so ordinary citizens could try to protect themselves from fake coins by checking their weight, but alloyed or counterfeit coins of the correct weight escaped detection when weighed on ordinary scales. Hydrostatic coin balances were manufactured by some makers to make it easier to detect these fake coins. 

Charles and Luke Proctor: Scientific Instrument Makers

Charles and Luke Proctor were one company that manufactured a hydrostatic balance. They were also makers of knives and forks, medals and other instruments such as ring dials in Sheffield between 1774 and 1787.

Ring dials were used as pocket sundials. Examples manufactured by the Proctors can be seen on the Museum of the History of Science website (Inventory Numbers 33544, 46125 and 48396). Several ring dials are also recorded on the PAS database, for example, SWYOR-2295A2 and even one made by the Proctors: WILT-554BA1 inscribed with their name.

Ring dial made by the Proctors
WILT-554BA1: a ring dial or pocket sundial stamped with the maker’s name: “Proctor” found in Wiltshire. Copyright: Salisbury and South Wiltshire Museum, CC BY-SA

A hydrostatic coin balance produced by Charles and Luke Proctor in Sheffield is pictured in ‘Equilibrium (1980)’, Quarterly Magazine of the International Society of Antique Scale Collectors.

The hydrostatic balance comprises a steel column screwed into a socket in a mahogany box. The column was used to support the scale beam. Brass weights for measuring different coins were provided with the mark C & L Proctor. Water weights were also provided for each coin.

The coin was weighed in the normal way by placing it in pincers below the small pan while the weights were placed in the other pan. Then the coin was immersed in water and the correct water weight was placed in the pan to counteract the buoyancy. A gold coin would balance level in both air and water, while a counterfeit coin, although weighing correctly in air, would float high in the water.

Coin weights were issued in Sheffield bearing the firm’s name, with some dating from 1773 suggesting the Proctors were making coin weights before the re-coinage occurred.

Coin weight made by C and L Proctor
FAJN-042103: a coin weight made by C and L Proctor, though not of the type stamped with their name. Copyright: Ashmolean Museum of Art and Archaeology, CC BY-SA

Charles and Luke Proctor: Silversmiths

In 1773, an assay office was established in Sheffield. Assay offices needed weights and scales to verify the fineness of samples and to check the weight of silverware to assess the duty that was payable. They also weighed coins offered in payment as the duty was part of the government’s revenue. Birmingham and other assay offices like Sheffield began verifying coin weights at the critical weight.

Charles and Luke Proctor’s firm also operated as silversmiths and their silver mark ‘C.L above P’ was registered with the assay office in Sheffield. It is suggested that silver production was a smaller part of the business.

Proctor and Beilby: Opticians

It seems that the Proctor firm took advantage of opportunities and adapted their business to suit changing business trends under the guidance of Charles Proctor.  When Luke Proctor left the firm, Charles Proctor continued the business with his sons and went on to develop an opticians business with Thomas Beilby.  The firm was the first in Sheffield to install a ‘rotary’ steam engine in 1786 which suggests successful large scale manufacturing. Proctor and Beilby had a large shop in Birmingham in 1788 and the Sheffield firm became Proctor and Beilby in 1800.

Telling Stories

One of the aims of the PAS is to share archaeological knowledge, by telling the stories of ordinary people as learned from the objects they left behind. The corroded and non-descript coin weight SWYOR-80FFA8 is  great example of how a mundane object can shed light on the past, in this case, the nefarious activities of Sheffield coin forgers in the past, and how it can illustrate the history of a local business and named individuals.


Edward Law. Sheffield Silver Smiths, Part 1. http://homepage.eircom.net/~lawed/SILVERSMITHSPART1.htm

Robert Eadon Leader. ‘Reminiscences of Old Sheffield: It’s Streets and its People’, (1876) Leader and Sons, (New York Public Library) downloaded from Google books [accessed 10.03.2020]

Biggs, N. (2004) PROVINCIAL COIN-WEIGHTS IN THE EIGHTEENTH CENTURY in BNJ 74. https://www.britnumsoc.org/publications/Digital%20BNJ/pdfs/2004_BNJ_74_10.pdf

Counterfeit Coin Detectors, Paper presented by M.A Crawford in ‘Equilibrium (1980)’, Quarterly Magazine of the International Society of Antique Scale Collectors, M. A Crawford (ed.), pps. 261-276 https://archive.org/details/equilibrium1980inte/mode/2up