These are beautifully expressive.

It Is amazing they have weathered the elements all these years.

These drawings were made by different artists living at different times. Some of them are related to:

Characteristics for the Occurrence of a High-Current, Z-Pinch Aurora as Recorded in Antiquity (2003)

https://archive.org/details/anthony-peratt-characteristics-f...

Part II of Characteristics For The Occurrence Of A High Current Z Pinch Aurora As Recorded In Antiquity Part: Directionality And Source (2007)

https://archive.org/details/characteristics-for-the-occurren...