History of the Typewriter

— 51 — to a long wooden lever, which passes from front to back of the machine. At the further end of the lever is a slot which admits a rod or fulcrum, F, upon which all the type levers swing. The typebars are of drop-forgings. One end of the bar carries the type, the other is fixed by means of a pivot of steel wire turned l-shaped at each end. On the top plate of the machine are screwed a number of U-shaped yokes, between the ends of which the l-shaped bearings swing. The typebar is connected to the lever by means of a connecting rod or wire, so that when the key is depressed it forces down the lever, which in its turn pulls down the free end of the typebar, which thus swings on its pivot, and forces the type upward on to the platen. Towards the further end of the lever will be seen a bar, Y, which passes under all the type-levers alike, and which is also forced down when a key is depressed. This second bar, which goes by the name of “The Universal Bar,” pulls down the rocking L-shaped piece, W. On the top of W are two small steel plates side by side. One of the plates, which are called “dogs,” is rigidly fixed to the rocker’ and merely takes the rocking movement conveyed to it by the depression of the Universal bar. The other, or “ loose dog,” is hinged, and is thrown forward in advance of the rigid dog just the distance of one tooth of the rack, which is a sawlike piece of metal fixed below the travelling portion of the machine called the “ carriage.” Now, when the rocking shaft is set in motion, the rigid dog, which has kept the carriage stationary during the repose ” of the machine, moves out of the rack, and the loose dog enters. I he carriage is being constantly pulled along by the strain of the mainspring, but when the rigid dog is in position is, of course, held in restraint. Directly, therefore, the rig d dog leaves the rack, and the loose dog enters, the restraint is taken off, and the carriage moves so far forward as the movement of the loose dog will allow it to. The carriage having travelled along, the action stops, as when the finger is taken off the key the lever returns to its natural position, the rigid dog takes the place of the loose dog, and all further movement is stopped until it is set again in motion by pressure on another key. This is the bed rock of the science of typewriter con- struction, and everything differing from this description is merely a difference in detail, and in no way affects the theory. In Figure 35 we have a sectional view of the new No. 10 Yost. In this machine the fulcrum is shifted from the