Pulley 4 with attached hand 5 rotates about fixed axis A. Flexible link 3 runs 360° around pulley 4 and is connected at point B to aneroid capsules (exhausted boxes) 1, and at point C to spring 2. When boxes 1 are deformed, hand 5 turns about axis A through an angle proportional to the deformation.
$3522$SFL,M$