In 1886 this same concern made a press which is still used for printing some of the forms of the _Century Magazine_. This press had two pairs of cylinders, and curved electrotype plates were used on it. The paper was in a roll at one end, and at the other end there were delivered, to each revolution of the cylinders, eight eight-page signatures already folded to the size of the _Century_ page. This was the first rotary press made for a good grade of book-work. Two similar presses were afterward made for _Harper's Weekly_ and for the _Strand Magazine_ of London.
What is known as the rotary art press was made in 1890 for printing the fine half-tone illustrations in the _Century Magazine_.
This has one plate cylinder and one impression cylinder, and curved electrotype plates are used. The sheets are "fed" by hand in the usual manner, and are printed on one side at a time and delivered by a sheet-flier. It produces as much work as four flat-bed cylinder presses and of better quality. The plates are inked by sixteen rollers. The performance of this press is another demonstration of the superiority of the rotary over the flat-bed principle of printing.
Since then hundreds of rotary presses have been made for magazine and book printing, most of them equipped with attachments for folding the sheets as they are printed, and all having a high rate of speed. C. B. Cottrell & Co. have made many rotary presses for magazine printing, most of which deliver the sheets flat, without folding, and most of them made to suit some predetermined size or sizes of sheets or pages.
In the evolution of the printing press there are three sharply defined stages: first, the flat impression surface and the flat printing surface, requiring the exertion of all of the impressing power upon the entire surfaces; second, the cylindrical impression surface and the flat printing surface, requiring the exertion of all of the impressing power upon only a narrow line or a small portion of the printing surface; third, a cylindrical impression surface and a cylindrical printing surface, still further reducing the area upon which all the impressing power is exerted.
Just as the second stage has, particularly for book-work, virtually superseded the first, so the third is destined to supersede the second. It is only an adaptation of the means to the ends. The mechanical principles of the rotary press are, in fact, simpler than those of the flat-bed cylinder press, and it may be said that so far as the purely mechanical part of the press is concerned, they have been fully developed, but much still remains to be done in other directions. The variety in the sizes of the pages of different books, the smallness of the editions, and the fact that the finer grades of paper, especially coated paper, cannot be obtained in roll form, are obstacles to be removed. As most book forms are electrotyped for flat-bed presses, and as it requires but little additional expense to curve the plates, this one item is not much of an obstacle to overcome. It is, however, still difficult to curve the plates perfectly, and the pressmen, even if they can produce excellent work from flat-bed presses, require considerable training if they have had no experience on rotary presses. All these difficulties are sure to be overcome in time.