In 1818 Edward Cowper received British patent No. 4194 for "Certain Improvements in Printing Presses or Machines Used for Printing." This described a method of printing on both sides of sheet simultaneously, also called a perfecting press. From this point forward most of the presses sold by Applegath and Cowper were perfecting cylinder presses. Presses of this design, or a modification of this design, were in wide use for decades.
"In January 1818 Cowper patented his ink-distributing table, which was attached to the forme, and indentations at its sides gave an endwise motion to two distributing rollers in a movable carriage held on four bearings, and with two small friction pulleys attached. The ink was conveyed by a vibrating roller which was alternately in contact with the table and with a 'ductor or doctor' roller turning in an ink trough. The table and forme both passed under the inking rollers, which received ink from the table and inked the forme as it passed under them. In Cowper's specification the rollers are described as 'covered with leather, felt, composition (treacle and glue) &c.', an indication that he was still gradually working his way towards composition rollers at the time.
"Another Cowper improvement [included in the patent] concerned the method of conveying the sheet of paper from one cylinder to another in a perfecting machine by the construction of two subsidiary 'carrying drums' between the impression cylinders, on which the sheet was carried by means of two sets of endless strings, 'each composed of two or more strings kept tight by weights or springs', the printing cylinders and carrying drums being connected by means of toothed wheels" (Moran, Printing Presses. History & Development from the Fifteenth Century to Modern Times  127).