Abstract: Automatically retractable chalk line assembly, including a housing having a pair of compartments, one of the compartments containing a spool having wound thereon a chalk line, and further containing a quantity of powdered chalk bathing the spool and line. The line passes outwardly of the compartment through a wiping member which removes excess chalk from the line. The other compartment houses a gear arrangement one side of which is connectable with a spur gear mounted on the spool and the other side connectable to a retractable assembly which includes a helical spring for applying rotational movement to the spool. The other end of the spool is connectable to a brake drum which immobilizes the spool from retracting until it is released by the brake drum upon actuation of a lever. The retractable assembly is provided with means for preventing the overwinding of the helical spring in the event that an abnormal amount of line is withdrawn from the chalk line assembly.

Abstract: This invention relates to metal-coated credit cards and to appliances for marking said credit cards in order to make deductions from the credit represented by the card. It is an object of the invention to provide such a card and marking appliance which can be used for an automatic accounting of services used for merchandise taken, such as copies taken from automatic copiers. For this purpose the metal-coated credit card which is adapted to be marked by a marking appliance in order to make deductions from the credit represented by the card has electrically conductive areas separated by electrically non-conducting areas. The credit card comprises a code-representing area, particularly at one edge of the card, and a credit-representing area which is spaced from the edges of the card and can be electrically marked in incremental areas in order to make deductions from the credit represented by the card.