There were 22 that ruled during that period.
Answer:
Employment is based on there being a profitable organization. This requires skilled human resources to do the work. As an organization grows it needs more human resources and needs new specialist skills. So there is a direct relationship between employment and skilled human resources.
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Explanation:
You might be surprised to find, however, that the first seismometer was invented in China in 132 AD by a Chinese astronomer, mathematician, engineer, and inventor called Zhang Heng. The instrument was said to resemble a wine jar six feet in diameter, with eight dragons positioned face down along the outside of the barrel, marking the primary compass directions. In each dragon’s mouth was a small bronze ball. Beneath the dragons sat eight bronze toads, with their broad mouths gaping to receive the balls. When the instrument sensed an incoming seismic wave, one of the balls would drop and the sound would alert observers to the earthquake, giving a rough indication of the earthquake’s direction of origin. The device is said to have been very accurate and could detect earthquakes from afar, and did not rely on shaking or movement in the location where the instrument was positioned. The first ever earthquake recorded by this seismograph was supposedly somewhere in the east. Days later, a rider from there reported this earthquake. Moreover, it had the most wicked ornaments. They don’t make scientific instruments like they used to! Of course, the insides of the seismometer was filled with a sensing mechanism of some sort, the contents of which have been lost in time. In all likelihood, a simple or inverted pendulum was employed, according to experts.
They must be kept on hand in order to meet central bank requirements. It ensures the safety of the nations financial institutions. It also is important so that banks always have some money on hand to prevent a run (the bank runs out of cash)