Preparation for observation of the Sun

Preparation for a black/cream observation of sunspots by John Willis. It's ready for use but there's no date. There are two spots. One of 275 pencil, ink and colour wash observations of the Sun and Jupiter made by Willis in Folkestone between 1879 and 1906.

Details

Category:
Art
Object Number:
2001-769/229
Materials:
paper, pencil, ink, col. wash
Measurements:
overall: 133 mm x 171 mm
type:
drawing
credit:
Sotheby's (Olympia)