The four great inventions

2016-09-20 点击量：

Printing technique dated from woodblock printingin Sui dynasty, and though development and improve-ment by Bi Sheng it created movable type printing,Mongals have spreaded this technique into Europe.Therefore Bi Sheng was recognized as grandfather ofprinting.Although woodblock printing played animportant role in the spread of information andcommercial transactions in China, it was a time-con-suming technology. Bi Sheng has improved this systembetween 1004 and 1048. He made one clay type for eachlinguistic character, then had them fired forhardness. A layer of resin, wax, and paper ashmixture was placed on the bottom of an open iron boxto hold the type with characters facing up. Thebottom of the box was heated to melt the wax mixture,and simultaneously all the typeface was pressed downwith a wood board to ensure that the types werelevel.Finally the tops of the clay types were inked,and the mechanism would then be ready for printingjust like a wood block. Afterward the clay typescould be disassembled and reused. The moveable-typeprinting process substantially reduced the time forprinting from several days to a matter of hours. Thistechnology is easy and simple, but had a significantimpact on the development of world history.
The invention of paper greatly contributed tothe spread and development of civilization. Beforeits invention, bones, tortoise shells, and bambooslips were all used as writing surfaces, but asChinese  civilization  developed  they  provedthemselves unsuitable because of their bulk andweight.Tshai Lun then initiated the idea of makingpaper from the bark of trees, remnants of hemp, ragsof cloth and fishing nets. Invention and spread ofpaper enable to reduce the cost and produce in largequantities, the knowledge could be widespread amongthe common people. It improved the economic andscientific development.
Unlike paper and printing, the birth ofgunpowder was quite accidental. It was firstinvented inadvertently by alchemists while attempt-ing to make an elixir of immorality. It was a mixtureof sulphur, saltpeter, and charcoal. At the end ofthe Tang Dynasty, gunpowder was being used inmilitary affairs. During the Song and YuanDynasties, frequent wars spurred the development ofcannons, and fire-arrows shot from bamboo tubes.Atsome point, they attached bamboo tubes to arrows andlaunched them with bows. Soon they discovered thatthese gunpowder tubes could launch themselves justby the power produced from the escaping gas. The truerocket was born.
A compass is an instrument containing a freelysuspended magnetic element which displays thedirection of the horizontal component of the Earth'smagnetic field at the point of observation.Duringthe Warring States period, a device called a Si Nanbecame the forerunner of the compass. A Si Nan was aladle-like magnet on a plate with the handle of theladle pointing to the south. In the 11th century,tiny needles made of magnetized steel were invented.One end of the needle points north while the otherpoints south. The compass was thus created. Thecompass greatly improved a ship's ability tonavigate over long distances. It was not until thebeginning of the 13th century that compass wasintroduced Arab, then to Europe from China.