The computation of the distance be-tween polyhedra in 3-space

A container for toothpaste, cream or other relatively viscous material has a forward continually open outlet or discharge portion, a one-way piston or follower in the container being disposed at the rear of the viscous or fluent material and sealingly engaging the container wall, the one-way follower being moved automatically by ambient air pressure toward the outlet after each dispensing of the material through the outlet, but gripping the container wall to prevent its retrograde movement during dispensing of the material, such dispensing occurring as a result of squeezing or deflecting a forward head portion of the container. The size of the outlet is so proportioned with respect to the viscosity or resistance to change of the fluent mass that retrograde flow of the fluent mass back through the container outlet is restricted upon release of the squeezing or deflecting action on the head, which results in a partial vacuum being created within the container, causing the atmospheric pressure to shift the one-way follower in the forward direction by a distance corresponding to the volume of the fluent material dispensed through the outlet.