18,341. Laganke, C. F., Smith, J. A., and Elliott-Fisher Co. Sept. 11. Calculating - apparatus; counting- apparatus. - A differential setting- mechanism for a master setting-wheel, consisting of a series of link-work and toothed segment combinations, each producing a rotation proportional to the value of the key by which it is operated, is mounted upon the movable carriage which supports the keyboard, type-ring, and associated parts of a Fisher typewriter adapted to print upon a fixed flat surface. The master-wheel thus engages successively with the pinions of a totalizing-counter normally fixed but adjustable with respect to the carriage, the whole arrangement constituting a single-bank key-operated printing adding-machine. Fig. 2 shows in transverse section the carriage 4, the eetting- mechanism contained in the transparent cover 106 thereon, the master setting-wheel 25, on the main spindle 26, and the counter casing 23 with its spindle 107, adjustable on the fixed cross-bar 21 by a wedge operated from the external knob 101. The magnifying-glass, mounted upon the counter, facilitates reading of the numerals which are placed upon the broad ends of the pinion teeth, and spacing-mechanism of the anchor and escapewheel type is operated by the universal bar 19 to rotate the pinion 15 along the rack 14. The differential movement is effected by a set of the following parts for each key. A fork on the horizontal projection 20 from each shank normally receives a pin on the link 47, which when depressed operates links 43, 41, having fixed centres at one end of each and a slotted intersection to swing the segment 40 through an angle determined by the proportions of the linlis, the parts being subsequently restored by a spring bolt 53. Each segment gears with a toothed lever 32, Fig. 11, which is loose upon the main shaft and carries 'a spring-pivoted pawl 34 for driving the corresponding ratchet-wheel keyed to the shaft. Overrunning is prevented and a full stroke ensured by (1) a spring detent for the master-wheel, (2) a second' detent for the same which is positively thrown into play when the pawl, at the end of its stroke,: strikes the proper arm 68 on the shaft to which the detent is pivoted, and (3) a fixed extension 70, Fig. 11, of the supporting-bracket for each ratchet-wheel, whereby the projection 61 upon the pawl is normally held out of engagement with its ratchet, but is positively put into gear when operated by the cam guard 60, which prevents the pawl rising to reverse the motion until the stroke has been complete, while upon the backward movement, it is lifted on to a rack 69 ensuring a full return. The total key, which is also used whenever the computing-arrangements are not required, rocks the shaft 73 and yoke '76 so as to swing the links 47 out of engagement with their key-projections, and the space corresponding to the decimal point is automatically inserted by the contact of the arm 91, Fig. 25, upon the carriage with a fixed tappet 96 upon the couuter casing, whereupon the arm 90, attached to the anchor spindle, is rocked and the escape-wheel makes an additional movement. The transfer mechanism is of the type in which a transfer lever moved by the lower wheel actuates and then locks the higher wheel, the motion of the master-wheel being always from left to right. Fig. 29 shows a transfer tooth 117 on the left side of a number-wheel depressing the projection 122 of the lever 109, pivoted upon the spindle 108 ; simultaneously, the pivoted dog 118 carried by the lever engages and moves the higher wheel, and finally the dog is pushed aside by the next tooth of the higher wheel acting on its curved surface while the action is completed and the wheel locked by the overhanging part 125 of the lever. To ensure engagement of the dogs, they are pressed forward at every spacing movement by a projection upon the carriage depressing teeth 130, Fig. 40, on the bent and pivoted yoke 126, 128. The following detent and restoring parts are provided :-The spring bolts shown press the detents 135 upwards ; the projection 154, Fig. 50, upon the carriage presses in a slide on the counter-casing at the end of the returning movement to the left, and thereby restores all the transfer levers by means of the angle levers 149, 148 ; the plate 167 extending from the carriage limits the transfer lever movement by contact with arms 168, another plate 164 with spring end slightly depresses the tops 163 of the levers to the left to prevent motion if a number-wheel comes to the "9" position with a shock, and a third plate 166 prevents accidental displacement of the lever feeding the wheel actuated. To zeroize the number-wheels, which have a cam and spring-pawl connexion with their spindle, as shown in Fig. 29, the spindle is rotated by means of a pinion thereon and a segment 174, Fig. 46, upon the zeroizing-lever, to which is attached a latch and latch-lever for locking it to the frame until the extremity 183 is grasped. The movement of the latch-lever also depresses the pivoted link 186 in order to actuate the transfer-lever restoring-slide and unlock all the wheels, and as the zeroizing-lever moves up the spring catch 191 swings above the shoulder 195. This enables the zeroizing-lever at the end of its return movement to again unlock all the wheels, which have become locked by the last step of zeroizing from. "9" to "0." As shown in Fig. 2, the counter bar 21 is supported on the main frame by means of screws and double nuts to allow of adjustment between the setting-wheel and counter pinions.