Patent GB-540604-A (GB)
Abstract: 540,604. Calculating-machines. MARCHANT CALCULATING MACHINE CO. April 11, 1940, No. 6583. Convention date, April 18, 1939. [Class 106 (i)] A multiplying apparatus comprises a keyboard by means of which one of the factors is set on a register, an adjustable device associated with the register for showing the position of the decimal point in this factor, a product register denominationally shiftable with respect to the factor register, and a device for indicating the position of the decimal point in this product, which device is carried by a part of the machine not moving with the product register and is adjustable relatively to the factor decimal point register. As shown, the multiplicand is set up on dials 301 by keys 100, the position of the decimal point 26 being indicated by operating the appropriate key 119. The multiplication is performed by maintaining an operating key 550 depressed until the first digit of the multiplier appears in the leftmost dial 900 of a multiplier factor register on a carriage 200. The carriage is then shifted by a shift lever 1015 one ordinal position to the left, and the second multiplier digit is then similarly set in the second dial 900, the process being repeated until the complete multiplier factor is shown, when the resulting product is displayed in product register dials 222 on the carriage 200. The device for indicating the position of the decimal point in the product comprises a member 27 slidable on a bar 20 secured to the frame of the machine and carrying a decimal point indicator 23 which is adjusted so that the number of multiplicand dials between it and the decimal point indicator 26 is equal to the number, of digits after the decimal point in the multiplier factor. Since the number of digits following the decimal point in a product is the sum of those following the decimal points in the factors, the indicator 23 indicates the position of the decimal point in the product shown in the dials 222. As a further aid in effecting the proper settings the machine shown is provided with an indicator 16 sliding on a fixed bar 11 and carrying a decimal point indicator 15 for the multiplier factor in the dials 900. The bars 11 and 27 carry numerals spaced at the same intervals as the dials 900 and 301. In use, the indicator 16 is set to the digit on the bar 11 corresponding to the digits after the decimal point in the multiplier, in the case shown two the indicator 26 is then set as above described, and finally the bar 27 is set so that the same number on it as that shown by the indicator 16 is set opposite the indicator 26. The indicators at the conclusion of the multiplication show the position of the decimal points in the multiplier, multiplicand, and the product, irrespective of whether the carriage 200 was at the extreme right-hand position or not in commencing. Further, should the multiplier have a different number of digits from that for which the indicators 16 and 27 are set, re-setting of these indicators may be avoided by shifting the carriage 200 'after completion of the multiplication until the decimal point 15 indicates correctly in relation to the multiplier factor in the dials 900, when the decimal point 23 will be correctly positioned relative to the product. The application of the invention to a machine of the type in which the carriage is shifted automatically after multiplication by each digit of the multiplier is described.