Undercover - In China - Book 7

Part 81 - The Three Kingdoms

The Three Kingdoms is a book attributed to Luo Guanzhou and first published in 1522 CE. It is a romanticised history covering a period of 112 years (from 168 to 280 CE) at the end of the Han Dynasty. 

 The author had access to detailed historical records of the period and contemporary critics noted that perhaps 70% was historically accurate. In China, this book has a status roughly equivalent to the works of Shakespeare. It has been translated into many languages and is the subject of many motion pictures including an epic series of 114 episodes. (Many of the photographs and video are from this work).

The events covered in Undercover in the Three Kingdoms are generally as described in the 1459 page translation of The Three Kingdoms by Moss Roberts, but I have used only a small part of the epic story and then compressed this into a very much shorter time frame. I also borrowed Kongming's Empty City Strategy from a much later period. 

Descriptions of Chinese technology are taken from The Genius of China by Robert Temple (3000 years of science, discovery and invention).

The Chinese invented techniques to drill boreholes up to 4,800 feet (1500 metres) deep more than 2000 years ago. The earliest records show tribes in the western Sechuan (Kingdom of Shu) were drilling in the third century B.C.E. They were looking for salt and they often found brine spurted out of the wells under pressure from natural gas. Brine could be found at depths between 100 ft. and 600 ft. and deeper holes also yielded natural gas, primarily methane. The deepest recorded was 4,800 ft. but most of them averaged 3,000 ft. By 1089 CE there were hundreds of them in the province of Chengdu alone. An imperial edict limited the district to 160 wells. Many were later capped to prevent or punish tax avoidance.

Two kinds of cast-iron drill bits were used. The larger was 10 ft. long and weighed 300 lb. It was used to pound the rock and widen the hole made by the smaller bit. The smaller bit weighed only a few dozen pounds.  The bit, suspended by bamboo cables from the derrick, would be lifted and dropped onto the rock. Men stepped onto a lever to raise the bit and jumped off again to let it crash down onto the rock. They did this for hours on end drilling from an inch to three feet per day. Sometimes it took years to drill a deep hole.

Ingenious devices were used to clear anything that might get stuck in the boreholes. The rock chips would either be mixed with water poured down the well or water which seeped into the borehole. So that the detritus from several successive drill smashes would be removed by suction through hollow bamboo tubes with leather flap valves at the end. The suction being provided by the double acting, piston air pumps used in Chinese steel making.

A single strand cable (made of bamboo strips 40 foot long) would be used down to 1500 ft. At greater depths the cable was of double thickness. Tensile strength of hemp rope is 750 lbs. per square inch, whereas that of bamboo was nearly 4 tons per square inch, similar to some steel wire. The bamboo was also so flexible it could easily be wound around the drill head winding drum. Bamboo cables had the added advantage of becoming tougher when wet, the opposite of hemp rope. In later medieval times a winding drum 40 ft in circumference (13 ft dia) was recorded as rotating 50 times to raise the bit to the surface indicating a depth of 2000 ft.

The brine was poured into huge cast iron evaporation pans and boiled for long periods, using natural gas if it was available, to evaporate the water.

Bamboo pipelines were used to carry both brine and natural gas for many miles. The use of natural gas for light and fuel posed problems. Gas from shallow wells could be piped directly to burners and safely lit. Gas from depths below 2,000 ft. had to be mixed with air, and the pressure regulated, before it could be safely burned.

Source: The Genius of China by Robert Temple (3000 years of science, discovery and invention).

There is, however, no evidence that water wheels were used as cable winches. But such wheels were used as a power source to raise water for irrigation.