Holiday was a keen student of astrology. He began to experiment with selenography, the scientific study of the moon, in the late 1860s, using his own telescope, and in 1870 he visited Robert Newall at Gateshead, who at that time owned the world's largest refractory telescope, in order to draw lunar craters. He had developed the ability to draw without moving his left eye from the lens, and was thus able to produce some astonishingly detailed drawings. Six of these were included in the Holiday Exhibition held at the William Morris Gallery, Walthamstow, in 1989, no.35.
Impressed by Holiday's lunar drawings, the astonomer Norman Lockyer invited him in 1871 to join a government-sponsored expedition to India to observe a solar eclipse. Holiday, who had been suffering from ill-health due to overwork, accepted without hesitation. The party, which also included Lorenzo Respighi, the Director of the Rome Observatory, sailed on S.S. Mirzapore and stayed in south India as guests of the Maharajah of Poodoocottah. After the eclipse, which took place on 12 December 1871, Holiday returned to England via Suez and Malta, having been away four months.
This attractive drawing, reminiscent of an Italian 'primitive',is reproduced in Holiday's autobiography, which contains a long account of the expedition. 'Here is a sketch', he writes, 'of some of the men at work, with a foreman directing and Sebastian, my servant, looking on'. Other drawings of the party's life in India, together with sketches made during the outward and homeward voyages, and drawings of the eclipse itself, were included in the 1989 exhibition, nos.36-9