Patent ID: 6978671

Claim:
A device for measuring and indicating the volume of the contents of a tank having a tank weight equal to the weight of the tank plus the weight of the contents of the tank, comprising: a fixed base; a spring deflectable with respect to said base, said spring supporting at least a portion of the tank weight; a band slidably received into said base, the movement of said band coupled to, and parallel with, the deflection of said spring; a diagonal slot in said base through which said band is visible such that said band is visible in a first position through said slot when the spring is at a first deflection under a first tank weight when the tank holds a first volume of contents, and visible in a second position through said slot when the spring is at a second deflection under a second tank weight less than said first tank weight when said tank holds a second volume of contents less than said first volume of contents; and a pin coupled to said spring and protruding through said slot.