Group of 275 pencil, ink and colour wash observations of the Sun and Jupiter made by Willis in Folkestone between 1879 and 1906. Some include detailed spot diagrams, and some manuscript notes on the viewing conditions.
Drawings 1-229 comprise studies of sunspots during 1882 (44), 1883 (5), 1884 (1), 1885 (12), 1893 (22), 1903 (1), 1904 (45), 1905 (96), and three undated.
Drawings 230-275 comprise studies of Jupiter during 1879 (1), 1885 (4 + 1 photograph), 1890 (3), 1891 (1), 1892 (1), 1904 (2), 1905 (5), 1906 (2), and six undated, and [20] other papers prepared but unused. -