History of the Typewriter

— 89 — viding a duplicate keyboard, so that on any two keys being struck simultaneously they would both print side by side. The mechanism by which this end was attained was remarkably simple. The hangers and type-bars were not arranged in a circle, as in the Remington, but in two perfect semi-circles, the centres of which are separated by a distance equal to the space between two letters of a printed word. All type-bars operating the left-centre were manipulated by the left hand, and those to the right by the right hand. The result was that in one operation either of the following combinations might be struck :— 1. Any capital letter and punctuation mark. 2. Any small letter and punctuation mark. 3. Any two small letters. 4. Any capital and small letter. It was therefore claimed that the speed power of the operator was doubled, and from the circumstance that the wear of the machine was extended over two alphabets instead of one, the durability of the machine was lengthened accordingly. The Duplex was well constructed, and incorporated a number of very useful devices. The carriage was very light, and was made to rest on and was guided by a series of hardened steel balls. One of the most interesting of the minor devices was an arrangement by means of which the position of the carriage could be slightly shifted, so that shaded letters for headings, or emphasised words, or ornament, could be easily made. The ribbon movement of the Duplex is thus described : The ribbon is moved by the carriage tension wheel, feeds across its entire width, and at the same time moves forward two spaces and again feeds across its width ; these movements continue in succession until the ribbon is wound from one spool to the other, when the movement is reversed, so that the entire surface of the ribbon is used in all kinds of writing. It is contended that by this means the ribbon cannot be hammered more at the centre than at the edges, and by reason of the constant movement referred to it cannot be worn more at one place than at another while printing a column of figures or a succession of short lines. A curious point in the Duplex was the ability to shift the carriage about the fortieth of an inch, so that a line of writing, if rewritten, would appear to be shaded, a very useful point in typing headlines or emphatic words.