First, the extinguisher valve is removed and the threads and interior of the cylinder are checked for corrosion, pitting, and any other abnormalities. [29 CFR 1910.157(f)(3)] If the cylinder passes the visual inspection, it is placed into a steel chamber, which is then filled with water at normal pressure.
Updated April 17, 2017. The earliest dated printed book known is the Diamond Sutra, printed in China in 868 CE. However, it is suspected that book printing may have occurred long before this date. In 1041, movable clay type was first invented in China.
By 1440 Gutenberg had established the basics of his printing press including the use of a mobile, reusable set of type, and within ten years he had constructed a working prototype of the press. In 1454 Gutenberg put his press to commercial use, producing thousands of indulgences for the Church. The following year he printed his famous 42-line Bible, the first book printed on a moveable type press in the West.