Invention which improved the printing technology after 17th century are listed below : (i) Metal Press : In the 19th century, there were a series of innovations in the printing technology. Now the press was made out of metal. (ii) Rotary Printing Press : Richard March Hoe, an American inventor designed and improved the printing press. He invented the Rotary Printing Press, a design much faster than the old flat-bed printing press. The new press could print* about 8,000 sheets per hour. The new press was very useful for printing newspapers. (iii) Offset Press : In the late nineteenth century, the offset press was developed which could print up to six colours at the same time. (iv) Electrically Operated Presses : From the turn of the twentieth century, electrically operated presses accelerated printing operations. A series of many other developments followed. Methods of feeding paper improved, the quality of plates became better, automatic paper reels and photoelectric control of the colour register were introduced. The accumulation of several individual mechanical improvements transformed the appearance of the printed texts.