Pale turquoise/yellow observation of the Sun, 15 May 1904

Pale turquoise/yellow observation of sunspots made by John Willis on 15 May 1904 at 5:40pm. On the reverse Willis has noted: "During this observation the sky was becoming obscured with very small clouds, or what is known as a 'mackerel' sky. JW." Mackerel sky refers to cirrus clouds. One of 275 pencil, ink and colour wash observations of the Sun and Jupiter made by Willis in Folkestone between 1879 and 1906.