GB210468A - Improvements in calculating machines - Google Patents

Abstract

210,468. Barr, J. M. M. Aug. 1, 1922. Adding and subtract. ing apparatus; multiplying and dividinq apparatus.-In key-set and independently electrically operated machines of the kind described in Specifications 5674/15, 5675/15, 203,236, and 203,351, and in which subtraction is effected by the addition of the complement, the key values are transferred to circuitclosing devices comprising groups of four contacts from which the digits can be made up for subsequent transmission to ball-actuated totalizing-counter mechanism. Three sets of circuit-closing devices are provided, one for the " item " and one for the " rate " in multiplication operations and one called " general " for operations involving addition and subtraction. The " item " and " rate " sets are associated with co-ordinating mechanism as described in Specification 208,737 for ascertaining the various partial products. The machine may be combined with any usual form of typewriter for printing any desired letterpress in addition to the numerals required. As shown, the current through the key-operated contacts passes by way of the leads h, Fig. 4, to one or other of a combination of the leads i, k, l as determined by selecting switches A - - D. The leads i, k, l are connected to corresponding " item, " " rate," and " general " circuit-closing devices, one of which sets is shown in Fig. 1 and comprises electromagnetically-operated switches d, spring-controlled slides a and two sets of contacts e, f arranged in groups of four, one for each denomination. The contacts e are normally open while the contacts f are normally closed. The particular group of contacts selected for receiving the key value depends on the carriage position, and that value is transmitted, when current is passed through the conductor e<1>, through leads e<2> to ball release mechanism for the counters, as described in Specification 208,737 referred to above. If the key value is to be subtracted the conductor e<3> is made alive to add the complement of the number set up. The arrangement of one of the totalizing-counters m - - p is shown in Fig. 2 with one denomination connected to the printing device r through normal and complementary contacts s, t. An additional counting disc q is provided to ensure that a single impulse will be given to the units denomination when subtracting a lesser number from a greater number. If the additional impulse is not required an electromagnet u is energized to ensure that the number printed will be the complement of that shown on the totalizing counter and be printed in a distinctive colour. A denomination-selecting distributor arm X, Fig. 3, is provided, and is so arranged with respect to the " rate " contact devices that its phase may be altered by means of a per cent or discount key for calculations dealing with percentages. The contacts A<1>, B<1>, &c. are associated with the thousands, hundreds, &c. contacts e, f for ordinary multiplication, while for percentage calculations the arm x is moved to the position C' for tens while the carriage is in the thousands denomination.