672,771. Calculating-apparatus. OLIVETTI & CIE. SOC. ANON., C. Dec. 30, 1947 [Aug. 26, 1944], No 34867/47. Class 106 (i). A multiplying mechanism for an adding and subtracting machine having a stop carriage and a supplementary keyboard on which the digits of the multiplier may be set in turn, is characterized in that operation of one of the multiplier keys " 6 " to " 9 " causes the machine to carry out a complementary number of subtraction cycles to effect a displacement of the stop carriage to the next higher order, and to carry out a subsequent addition cycle. The multiplier keys, Fig. 2, are arranged in two adjacent rows and depression of any one moves a slide 3, Fig. 3, which has cam slots to co-operate with pins in the key-stems. At the same time the key depresses the appropriate one of five spring bars 4 which correspond with the five complementary pairs of keys and are mounted in a slidable frame 12. The bar 4 rocks a yoke 5 which through a slide 6, rocks a lever 7 to lock the key-operated slide 3 and to move a link 8 which causes the machine-drive to operate. At each cycle, a pawl 11 on a rotating arm advances a rack 9, which co-operates with a pawl 10, by one step, until an abutment on the rack engages the depressed bar 4 and slides the frame 12 against a spring until the bar is moved from beneath the depressed key-stem and restored by its spring. The machine is normally conditioned for addition. If the depressed key was one of the keys "1" to " 5," the yoke 5, slide 6 and lever 7 are also restored so that the slide 3 and depressed key are released and the link 8 is free to be restored at the end of the cycle to stop the machine. A link 22 is also restored to move the stop carriage to the next higher denomination. However, if one of the keys " 6 "-" 9 " is depressed, a yoke 21, Fig. 4, is also rocked and, through a bar 13 and lever 14, shifts a link 15 which conditions the machine for subtraction. The lever 14 also causes an arm 17 to engage behind a pin in the starting link 8, in which latching position it is locked by a sprung lever 18. When the slide 12 is moved by the rack 9, the bar 13 is rocked and disengaged from a pin in the yoke 21 to allow the lever 14 to be restored so that the machine is conditioned for addition again. By virtue of the latch 17 the machine continues to operate for a further cycle after the link 22, Fig. 3, has moved the stop carriage to the next higher denomination and during this cycle, a cam 19 rocks the lever 18 to release the latch 17 and allow the link 8 to be restored to stop the machine. If the zero key is depressed, known mechanism merely causes a shift of the stop carriage.