Measurement apparatus with pendulum-based plumb indication and fluid-based level indication

A measurement apparatus comprising:

• a housing defining a sealed chamber and a viewing window, the viewing window comprising at least one transparent face of the housing;
• a fluid disposed within the sealed chamber to occupy a first portion of a volume of the sealed chamber, wherein a fluid interface between the fluid and a headspace above the fluid provides a level reference across the viewing window;
• a pendulum disposed within the sealed chamber and pivotably supported for rotation about a pivot axis located at or proximate a geometric center of the sealed chamber, wherein at least a portion of the pendulum extends through the fluid, and wherein the pendulum is configured to align with a direction of gravity independently of an orientation of the housing to provide a plumb reference visible through the viewing window concurrently with the level reference provided by the fluid interface;
• and
• a plurality of exterior indicia disposed along a circumference of the housing and adjacent the viewing window, the plurality of exterior indicia including at least:
• a first pair of opposed level reference marks corresponding to the level reference, and a second pair of opposed plumb reference marks angularly offset from the first pair of opposed level reference marks.