Problems with determining quantities
Early records of measuring weight
The oldest record of an unfavorable trade and the ensuing punishment is to be found in the Code of Hammurabi from cca 1750 BC.
“If an inn-keeper refuses to accept crop in exchange for beer, but only accepts silver measured using a large weigh – thus lowering the value of beer in relation to crops – then they shall find she has erred, and she shall be thrown into the river.”
How to measure the value of something that cannot be counted or measured using standardized measures such as the inch or the foot?
Balance scales
We can compare the weight of two objects by holding them in our hands. But is this accurate? Of course not, because our hands and arms send signals to our brain separately. But what would happen if our hands were firmly connected by, say, a metal rod? That would already form a balanced lever, which acts pretty much in the same way as balance scales. The Egyptian Book of the Dead from 1250 B.C. details the use of balance scales to compare the weight of two objects. The dead were allowed to enter the underworld only if the weight of their heart was measured against the feather of truth.
The balance scale was a useful tool for comparing two different objects or materials. It consisted of a balanced beam (propped up in the middle), with one pan or hook on either side. Instead of relying on your feelings as to which of the two hands must exert greater force to hold the object, you placed these two objects on the pans or hooks and watched the beam tilt to one side or the other.
If you were to measure identical quantities, you would either add more material to the lighter side or remove bits of material from the heavier side, until the beam was balanced in a horizontal position.
Using weights in balance scales
Our ancestors knew that if they weighed goods against an object whose weight remained the same, they could determine the weight of the goods in relation to this object. This is how weights came into being. The oldest known weights were made of flint came from the valley of the Indus river and from Egypt, roughly 4000 B.C.
Other types of weights
You can imagine how difficult it was back then – without postal service or the internet – to spread the same standardized weights across the country and avoid forgeries. Therefore, people in different cultures discovered – quite independently of one another – that certain objects or materials in nature are remarkably stable in their shapes and sizes. This was particularly true of plant seeds – cereals, carob (or Saint John’s bread), millet etc. It may seem primitive today, but the truth remains that natural laws determined millions of years ago the size of a seed that is capable of growing into a new plant.
The downside was that these natural weights were tiny; you had to use many seeds at once and before every measurement, you had to count them or determine their overall volume.
Standardized weights
Seeds were unsuitable in measuring the weight of heavier goods or larger amounts. Therefore, people in ancient cultures began to use weights made of precious metals, glass or various alloys such as bronze. Their main advantage was durability, together with the fact that neither the materials, nor the technologies to manufacture them were easily available – which made the production of forgeries rather difficult. The weights were cast in moulds and it was the ruler’s duty to oversee weighing standards and their application in trading. This gave rise – as early as the antiquity – to the connection between balance, honesty and divine justice.
Even today, we are still fascinated by the effectiveness of the ancient civil authorities, able to enforce and maintain the same weighing standards that were essential for trading – both inland and in colonies overseas.
The disadvantages of the balance scale
Using balance scales had some disadvantages, despite using weights of different sizes. As the very name suggests, to keep the balance, both arms of the scale had to be the exact same length, and the weights had to correspond exactly to the weight of the object measured. This became problematic, especially when available space was limited, or large objects measured – for instance, when you were to weigh cargo unloaded from a ship. Also, you needed scales with a longer beam to measure the weight of a goat or a cow, and much smaller scales to measure a flacon of rose oil – and keeping large numbers of different scales was not very effective – not to mention the great number of standardized weights you would need to keep, and the clumsy heavy ones you would need to move around.
Therefore, in the 1st century A.D., the so called steelyard balance was invented, with arms of unequal length.
The Roman steelyard balance
The steelyard balance, or the so called Roman scale, was invented in the 1st century A.D. The scale was not very accurate, but it was capable of measuring goods from 10 Kg up to 110 Kg, using only one movable weight.
The steelyard consisted of a beam with two parts of unequal length, a dial, a movable weight and three hooks. The hook on the furthest side held the goods that were to be measured, while the other two hooks were used to hang the steelyard – one for goods between 10 and 35 Kg, and the other for heavier goods.
Using the steelyard balance
The obvious advantage of the steelyard was in using only one single weight, which was moved along the longer arm of the scale.
In determining weight, only two hooks were used at a time. For lighter goods, hook “A” was used, being closest to the longer arm of the scale. You would use this hook to hang the steelyard up on a beam or a frame.
On the furthest hook, you place the goods, while leaving the middle hook empty. Then, you move the weight back and forth on the longer arm, until the scale is balanced. When you have reached that balance, you read the measured value from the dial.
If the goods were expected to be heavier than 35 Kg, the steelyard would be turned around and you used the middle hook to hang it up, thus increasing the length ratio between the two arms. The weight and the hook for hanging goods were also turned around and the process was repeated, as described above.
As with any lever with arms of unequal length, balance was not achieved simply by equating weights on both sides of the scale. Rather than that, it was the product of the size of the weight and the length of the arm from the weight to the central part. Therefore, a small weight placed further from the center could create a balance with a much heavier object on the other side.
The disadvantage of the steelyard balance lay in its low accuracy. Therefore, in the case of rare and expensive goods, people looked for different weighing methods.
Using the steelyard balance
The obvious advantage of the steelyard was in using only one single weight, which was moved along the longer arm of the scale.
In determining weight, only two hooks were used at a time. For lighter goods, hook “A” was used, being closest to the longer arm of the scale. You would use this hook to hang the steelyard up on a beam or a frame.
On the furthest hook, you place the goods, while leaving the middle hook empty. Then, you move the weight back and forth on the longer arm, until the scale is balanced. When you have reached that balance, you read the measured value from the dial.
If the goods were expected to be heavier than 35 Kg, the steelyard would be turned around and you used the middle hook to hang it up, thus increasing the length ratio between the two arms. The weight and the hook for hanging goods were also turned around and the process was repeated, as described above.
As with any lever with arms of unequal length, balance was not achieved simply by equating weights on both sides of the scale. Rather than that, it was the product of the size of the weight and the length of the arm from the weight to the central part. Therefore, a small weight placed further from the center could create a balance with a much heavier object on the other side.
The disadvantage of the steelyard balance lay in its low accuracy. Therefore, in the case of rare and expensive goods, people looked for different weighing methods.
Accurate scales
Merchants in rare and expensive goods were not troubled by heavy weights, unlike lime merchants or cattle merchants. Their major concern was accuracy. They needed to determine exactly when the two arms of the scales are in balance. Therefore, a pointer (or balance indicator) was attached perpendicular to the beam. When the pointer was perfectly vertical, without tilting to either side, there was balance between goods on one end and the weights on the other. Another way to solve this problem was to place the pans above the beam and attach pointers to them – when the pointers met, the two pans were in balance – together with anything that was placed on them.
The Decimal scale
The accuracy of the measurement was also influenced by placing the goods on different places on the pan – the further from the center of the pan, the less accurate the measurement.
However, how can you force cattle, for instance, to stand still and in the center? This problem was solved by the so called decimal scale. The decimal scale was a type of balance with arms of unequal length. The arm holding the weight was ten times longer than the arm holding the goods, which, amongst other things, allowed using weights that were ten times lighter than the goods measured.
In the case of the decimal scale, the accuracy problem was solved by a special mechanism. The floating bridge of the scale allows us to place the goods on any place on it, as long as the scale is in a horizontal position.
The decimal scale – a description
The decimal scale consists of a bridge, a beam, a fixing element, a lead and a pan for placing the weight (or, alternately, a movable weight). A more advanced type of the decimal scale might have two movable weights, one for kilograms and one for tenths of a kilo. The movable weights fall into notches while traveling on the beam.
Scales and measuring weight in the mill
Mill probes
Do you know what a mill probe was, and how it was used?
The technical procedure of flour milling in the watermill consisted of a number of different stages – moistening, piercing, grinding, multiple milling and then sieving the flour or semolina.
Wheat was processed using the so called upright technique. Gradually, the process yielded semolina, cake flour, fine semolina, white flour and several other flour types.
On the other hand, rye was processed using the “flat milling technique”, yielding white flour, dark flour and superfine flour.
In other words, it was very difficult to determine beforehand exactly how much of each type of flour or semolina will be produced.
So, from mid-16th century, mill probes were used in Czech mills. A probe consisted in preparing a test sample, to determine how much of each type of flour or semolina will be produced.
The General Milling Code, set up by Emperor Francis in 1814, ordered every miller to own and use a genuine, calibrated scale.
Both the crops and the resulting flour, together with the bran, had to be measured on a balance scale with the correct weights.
If the miller were to keep using a steelyard balance, they were to be confiscated, sold as scrap metal, the money given to the poor and the miller was to be punished.
