Emperor Ling creates Consort He as the new empress and makes her brother He Jin a key official in his government in 180.

(According to legends, she had initially been selected as an imperial consort because her family had bribed the eunuchs.)

She receives the empress position because she has given birth to Emperor Ling's son Liu Bian.

During the past few years, Emperor Ling has become interested in heavy spending to build imperial gardens, and to finance them he has ordered the prefectures and principalities to offer tributes to him personally.

This in turn has created pressures for officials to become corrupt.

However, he also listens to good advice at times, but does not follow his advisors consistently.

For the more honest of his officials, it has become a frustrating exercise to try to persuade Emperor Ling on points that are beneficial to the people—because he can in fact sometimes be persuaded, but not usually.

Evidence of Han-era mechanical engineering comes largely from the choice observational writings of sometimes disinterested Confucian scholars.

Professional artisan-engineers do not leave behind detailed records of their work.

Han scholars, who often have little or no expertise in mechanical engineering, sometimes provide insufficient information on the various technologies they describe.

Nevertheless, some Han literary sources provide crucial information.

For example, in 15 BCE the philosopher Yang Xiong described the invention of the belt drive for a quilling machine, which was of great importance to early textile manufacturing.

The inventions of the artisan-engineer Ding Huan are mentioned in the Miscellaneous Notes on the Western Capital.

Around 180 CE, Ding creates a manually operated rotary fan used for air conditioning within palace buildings.

Ding also uses gimbals as pivotal supports for one of his incense burners and invented the world's first known zoetrope lamp.

(Needham, Joseph.

[1986c].

Science and Civilisation in China: Volume 4, Physics and Physical Technology; Part 2, Mechanical Engineering.

Taipei: Caves Books Ltd) Modern archaeology has led to the discovery of Han artwork portraying inventions which are otherwise absent in Han literary sources.

As observed in Han miniature tomb models, but not in literary sources, the crank handle is used to operate the fans of winnowing machines that separate grain from chaff.

The odometer cart, invented during Han times, measures journey lengths, using mechanical figures banging drums and gongs to indicate each distance traveled.

This invention is depicted in Han artwork by the second century CE, yet detailed written descriptions are not offered until the third century CE.

Modern archaeologists have also unearthed specimens of devices used during the Han Dynasty, for example a pair of sliding metal calipers used by craftsmen for making minute measurements.

These calipers contain inscriptions of the exact day and year they were manufactured.

These tools are not mentioned in any Han literary sources.