As paper strip a passes over measuring roll d, it rotates the roll and gear 1 which is rigidly attached to roll d. From gear 1 rotation is transmitted through gear 2 to shaft b. When clutch 3 is engaged, rotation is transmitted further to shaft c and worm 4 which is keyed on shaft c. Worm 4 drives worm wheel 5 and gears 6 and 7. This turns hand e on meter dial 8. When the paper strip tears, lever 9 is raised by spring 10 and it disengages clutch 11, stopping the meter.
$2551$LrG,FD$