NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Agnostic gnomon and horary error
From: Chuck Varney
Date: 2024 Jun 5, 11:43 -0700
From: Chuck Varney
Date: 2024 Jun 5, 11:43 -0700
Frank Reed,
Thank you for posting the photos you took at Mystic Seaport last weekend.
The two armillary sphere photos confirm what seemed evident from the “Sundial” cover photo; namely, that Edwin Pugsley got his signals crossed when positioning the support post in the 90-degree arc between the gnomon lower end and the equator / time scale ring. This resulted in having the gnomon elevation at, or near, the colatitude angle rather than the latitude angle.
Using an IrfanView graphic viewer, I got 49.2 degrees as the average of five measurements of the gnomon angle in your first sphere photo. This compares to the 49.3 degree average that I measured on the “Sundials” cover crop that I posted earlier.
Chuck V.
