As the use of the addressograph increased, Mr. Duncan and Mr. Hall realized the need of a more efficient way of making changes and additions to the list of names. It was important that individual names be located and removed from the list more quickly than was possible with the chain addressograph. Demand for improvement along this line was stimulated by the loose-leaf and card index wave which was just then beginning to sweep the country. And Mr. Duncan, taking the card index idea as a basis, designed what he called the Model "A" or Rubber Card Index Addressograph. Instead of the separate plates being linked together in the form of a chain, they were inserted into a tin holder - called the frame - which closely resembled in appearance a 3x5 paper file card. In addition to carrying a printing plate, this frame also carried a paper card bearing a proof of its respective printing plate. In this complete form, these address plates were filed in steel filing drawers like ordinary paper cards. About every fifteenth address plate in a drawer was equipped with a vertical, subdividing tab - numerical, alphabetical or geographical as the case might require. Each filing drawer carried a printed label showing the contents of the drawer - and by means of these complete card index features it proved a simple matter to locate and remove individual names when making revisions to the list; and, in addition, these features afforded all of the advantages of a perfect reference file, as the paper proof card could be provided with a printed form for retaining memoranda.

Of course, a new addressograph was necessary to handle this card index improvement. And in the Model "A" Addressograph, we find the basic principle of the addressograph of today. A drawerful of plates is emptied into the magazine. The empty filing drawer is placed beneath the addressograph so that after addressing the address plates fall back into the original drawer in their original card index order.