The carbon process enables the answers to be filed with the original letter.
The modern chemical letter copier offers distinct advantages over other methods. It consists of a simple machine designed to carry a roll of specially prepared paper. The letter to be copied is laid on the feed board, the handle is turned, the sheet is fed automatically into the machine.
It will be noticed that a water bath and brush or damping sheets, are completely dispensed with; there is no "off-sheeting" and no drying drum. The copy may be either filed with the letter to which it relates, or placed, day by day, in a cover having the appearance of an ordinary letter-book; or two copies can be made of each letter—one for filing and the other for the book.
(1). A type-writer should be durable. Every part should be simple and strong and adapted to serve its purpose with the smallest degree of wear. Every mechanical movement must be definite, and incapable of incomplete performance. All wearing parts should be adjustable and interchangeable.
(2). It should possess absolutely "visible" writing. The common-sense way to write easily and speedily is to see what you are writing while you are writing it.
The writing should be performed in such a part of the machine as to be most readily seen during progress.
(3). The keyboard—on type bar machines in particular—should be that known as the "Universal," or "Standard" arrangement.
The keys on any style of keyboard should have a light and uniform depression, so that the machine may be operated with the minimum of fatigue.
(4). The types should present an even and regular appearance, termed "alignment." A type bar made of suitable material in the right way is the keystone of typewriter construction. In all machinery, there is some part on which falls the greatest strain and wear; consequently on the durability of that part rests the life of the machine. The devices used to secure alignment are numerous and ingenious. One machine depends on a wide pivoted bearing and a rigid type bar; another has a bearing composed of a continuous steel rod, with a type bar flexible while in motion, and made rigid at the printing point by means of guides; a third employs a wide pivotal bearing, a flexible type bar and an indispensable guide plate at the printing point; a fourth employs a compound type bar and an indispensable guide at the printing centre, and so on. Some have wide and adjustable bearings, to enable the wear to be taken up. These devices, however, are not the only essentials. The type bar hangers in machines embodying the pivotal principle need to be rigid and solidly fixed, while the paper carriage should be perfectly rigid and present a level and even platen surface for the type to strike against.
(5). The type should be capable of being easily and quickly cleaned, and in such a way as not to injure the type or soil the hands. A device should be embodied for rendering it impossible to batter the face of the type when the type bars are accidentally struck one against the other, and for preventing the type perforating or puncturing the platen.