586,709. Book-keeping. AKKER, M. A. H. VAN DEN. Sept. 10, 1941, No. 11593. Convention date, Aug. 3, 1940. [Class 16] A book-keeping apparatus comprises a table 1 to which are clamped a duplicate or control sheet and an overlying carbon sheet, a carriage which includes a vertical ruler 8 adapted to be displaced with respect to the table 1 and carrying an entry sheet, and a zig-zag shaped guide path for the carriage wherein the turning points of the points of the path provide arresting points for the carriage. Of the two book-keeping sheets (not shown), the bottom or control sheet 46 has the entries arranged in tabular form, and the top or entry sheet 45 has the entries made in single column each for debit and credit. The sheet 46, is clamped on the table 1 by spring clamps 2, 3, and the carbon sheet by a spring clamp 4, the handle 6 of the clamps 2, 3 being arranged to engage the handle 5 of clamp 4 to open the latter, if necessary. The entry sheet 45 is clamped between a fixed part 12 and a spring-pressed jaw 11 forming part of the vertical ruler 8 on which is arranged a member 14 carrying a horizontal ruler 15, or line indicator, adapted to slide vertically of the ruler 8. Recesses 16 in the ruler 8 indicate line spaces. The ruler 8 is hinged at 17 to a carrier 25 which passes beneath the table 1 to the bottom thereof where it serves to anchor the bottom free end of the ruler 8 as by providing a support 20 for a locking-pin 22. The table 1 is supported above a plate 7 on which are secured two strips 27, 28 formed with zig-zag grooves 29, 30, respectively, these grooves being engaged by pairs of balls 33, 34 and 35, 36 respectively located in holes in back of two arms 26 secured to the carrier 25. Further balls 37, 38 in the arms 26 roll on a plate beneath the table 1, and leaf spring 39 on the arms 26 engage these balls to urge the plate 26 into engagement with the balls 33-36. If the ruler 8 is moved from the neutral position shown in Fig. 1 to the arresting position 41 the entry sheet 45 is lowered one line space, and if it is then moved to the position 43 the sheet rises two line spaces above the neutral position. The zig-zag path to the right of the neutral position is similarly shaped to enable credit entries to be made. At one stage in each book-keeping operation the entry on the' entry sheet 45 is duplicated on the control sheet 46 by tracing this entry by means of a tracing element forming part of a fountain pen.