The development history of weighing instrument

The first weighing device is recognized to have appeared in Egypt and Babylon, as early as 5000 BC. This ancient weighing instrument uses a simple wooden balance with a hole at each end and a hole in the middle. The rope passing through the middle hole is used to support the balance beam. The weighing pan is supported by ropes passing through holes at both ends of the balance beam. This structure is called an "equal-arm balance". The weight of an object in one weighing pan is equal to the weight of an object in another weighing pan, and the central support serves as a fulcrum.
Around 2000 BC, people made some improvements to the original structure. A vertical hole was drilled from the top of the balance to connect the horizontal holes at each end of the balance. The sling of each weighing pan passes through the vertical hole through the horizontal hole to the weighing pan. In this way, due to the weight of the weighing pan, the sling remains in fixed contact with the ends of the balance beam. This improvement helps to more accurately determine the length of the lever arm.
This kind of balance is a known weighing instrument before Roman times. However, this does not mean that it maintains its original structure. During this five thousand years, the main improvement is to greatly improve the accuracy and convenience of the balance.
In about 1000 BC, the above-mentioned weighing instrument was improved by replacing the rope pivot with a bronze ring. Although the bronze ring does not improve the accuracy of the weighing instrument, it does improve the portability and convenience, thereby making the use of the weighing instrument more common. Then, around 500 BC, hooks and loops were used. Fix the pivot pin on the shackle so that the balance beam can be easily removed from the pivot pin. Soon, by shifting the support shaft off the center, the lower load can balance the heavier load, and the use of multiple levers (non-equal arm balances) is started.
For thousands of years, equal-arm balances have been weighing instruments used worldwide. Around 400 BC, a new weighing principle appeared, known as the "Danish Bismarck Weighing Apparatus". It includes a wooden pole and a weighing hook. The wooden pole fixes a larger weight on one end, and the weighing hook is used for the load on the other end. The fulcrum can be moved, and the rope or metal ring slides along the weighing beam until it is balanced.
Read the weight through the series of notches on the underside of the scale. Although it is not accurate, it is very popular all over the world and uses different names. Referred to as weighing controller
This kind of balance underwent important improvements in 200 BC, when the Romans invented the steelyard. Steelyards are different from Bismarck's scales in that they have a weighing pole with a fixed pivot and are based on the principle of equal moments.
The steelyard is considered a reliable and accurate weighing instrument. The principle is to apply force from a distance. The product of force multiplied by distance is called "moment". If the sum of the two moments is equal, the system is considered to be in equilibrium.
The steelyard is also the first to use the principle of sliding weights. One weighing hook is fixed on the shorter arm to support the load, and the other weighing hook is fixed to the second fulcrum for supporting or hanging the steelyard. The load is weighed by moving the weight along the weighing pole. Compared with equal-arm balances, the big advantage of steelyards is that they can weigh heavier loads with lighter weights. For example, the beam of an equal-arm balance is a single lever with a ratio of 1:1; the beam of a steelyard is a multiple lever with a ratio of 5:1.
In 1490 AD, Leonardo da Vinci, a famous painter, sculptor, architect and engineer, designed a weighing instrument with automatic balance and automatic indication.
He used the same principle to design two weighing instrument structures. In one structure, the semicircular weighing pan is suspended on the column by means of a rotating shaft, and the rotating shaft is located at the center of the diameter of the weighing pan. The weight hanging on one corner of the weighing pan makes the scale rotate, thereby slowly increasing the weight corresponding to the load. When these two weights are balanced, the rotation stops.
The other adopts a triangular structure, the triangle is hung on its height, and the load is hung on a corner of the triangular base. In this case, the load causes the triangle to pivot around its axis in the same way as the semicircular scale. Da Vinci's automatic indicating weighing instrument is as important as the automatic balancing instrument. This kind of weighing instrument has a reader, which is located on the curved surface of the weighing pan, and the development of three weighing instruments