"Back of the Envelope"

An informal illustration of technology in action


Sketch by Jonathan Sills
The Mural Quadrant

The mural quadrant was fixed to a sturdy wall within the observatory, and aligned with the meridian (an imaginary line through the poles).

The observer pivoted the telescope along the graduated scale until a targeted star was in view. The star's altitude could then be measured using the highly accurate divisions on the quadrant.

Sometimes a ladder or reclining chair was necessary to achieve just the right angle for making the observation.


VIEW A MURAL QUADRANT FROM THE MUSEUM'S COLLECTION

Back to the main page