TYPEWRITING MACHINES.
As early as 1714 Henry Mill patented a machine which he " had brought to perfection at great paines and expence,'* for impressing letters on paper as in writing; no drawings or particulars are, however, given. In America the first record of any kind is the patent granted in 1829 to William A. Burt for a " typographer/' All record of this machine perished in a fire at Washington in 1836. In 1833 Mons. X. Progin, of Marseilles, patented a " ktypographic machine or pen," which is remarkable as being the first to embody the type-bar principle.
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Typewriting machines may now be classed imder three heads, viz. : index machines, type-wheel machines, and type-bar machines.
Type-bar machines, however, embrace by far the largest number of modern typewriters. All of these have keyboards, and the type are on pivoted bars, arranged in a circle or segment of a circle, and strike to a common printing point ; the inking is usually done by a ribbon, but in some machines by a pad.
To this class belonged the machines of Francis and Beach, while many examples of modem type-bar machines will be found in the collection. Some of the later machines give " differential" spacing, by which the feed after a letter is printed varies with the width of the character, a modification that somewhat improves the appearance of the work produced.
1474. Sholes & Glidden typewriter. Presented by Lady Brassey, 1881. M. 1512.
This is one of the original machines invented by Messra. C. Latham Sholes & Carlos Glidden, between 1867 and 1873. It was manufactured and introduced by Messrs. E. Remington & Sons, of Ilion, New York, in 1875, and was a soimd practical machine, but only wrote in capital letters.
It is a type-bar machine, with the levers hanging vertically round a circular opening in the top of the frame, so that the type strike upwards at the common centre. There are 44 keys, connected by horizontal levers and
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vertical wires to the same number of tjpe-bars. Each bar has but one character, so there is no change of case.
The platen cylinder is supported in a carriage, that slides on a rod at the back and is supported by a wheel in front. The paper, which may be of any length but not more than 8 ' 25 in. wide, passes under the platen cylinder, with which it is held in contact by two rubber bands passing round rollers on the carriage. To inspect the work, the caiiiage can be swung upwards roiuid the guide rod, which acts also as a hinge. The carriage is continuously pulled to the left by a spring, the motion b^g checked by a rack attached to the carriage, and engaging with two yibrating detents that release one tooth with each character printed. At the end of a line the carriage is returned and the cylinder sHghtly rotated by a cord attached to an external lever at the right-hand side; this return movement also winds up the feeding spring.
Ii￡ng is done by a wide ribbon, interposed between the paper and the type. The ribbon stretches horizontally over the top of the framing from a spool on each side, and is slowly woimd alternately from one to the other by the motion of the machine ; the reversal of the winding, when either spool is emptied, is performed by a hand-moved clutch.
The arrangement of this keyboard has since been adopted in neariy all tyi)ewi'iting machines, and is now known as the " universal." In front of the four rows of keys is a long space-key, for moving the carriage at .the end of each word.
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最終更新：2009年09月22日 14:01
