The different units of a rotary printing press, such as roller drivers, printing units and ink fountains, autopaster, the folding mechanism as well as the entire paper fee ding device form a unit of work, the entire groups of which must cooperate in harmony to achieve optimum printing quality and highest output. Especially the behavior of the paper and the paper feed often cause interruptions in the manufacturing process, particularly on account of the ever-increasing operating speed. For this reason this problem is dealt with here in detail. First the requirements of the printing technique are outlined which the printing material, paper, has to meet nowadays. Then it is tried to outline the causes for the interruptions in the operation of rotary printing presses and how to eliminate them. The printer wants to have the same quality of performance throughout the entire process even at a high printing speed with a minimum of waste paper and unproductive stoppage of the press. Thus the modern high-speed presses require an unobjectionable paper reel, too. As a matter of fact, the printer must on his part do everything possible not to disturb the equilibrium ratio in the paper feed. Automatie devices to measure and control the paper facilitate his work with the presses. The paper manufacturer endeavours to supply homogeneous and faultless papers ready for use which were manufactured by his machines that are operated by controllers and which were selected by the printer according to their printability. Intelligent printers know of the thorny ways the paper manufacturer has frequently to choose in order to meet the ever-increasing requirements in which the price of the paper often plays an important part. Exhaustive researches in the field of printing and paper techniques along with practical observations inside the plants are necessary in future, too. An exact examination of the causes for varying web tensions in units and their consequences, especially examining the elastic behaviour of paper, is of special importance. In order to successfully fight the causes of bottlenecks and to study the motions of different machine mechanisms in the rotary printing presses the "Institut für Druckmaschinen und Druckverfahren der Technischen Hochschule Darmstadt" (Institute for Printing Presses and Printing processes of the Technical College Darmstadt) has successfully used high-frequency cine-cameras. This will occassionally be dealt with in another article. Only through constant, sympathetic and fair cooperation between the printers and the experts of paper manufacture, a paper may be supplied that is not only best suited for the different rotary printing presses but also inexpensive and in a good condition when supplied.