Isaac Frost was a scientist and prominent member of the Muggltonian sect in the mid nineteenth-century. He was instrumental in the refinement of the Muggletonian’s geocentric astronomical theory, as presented on the plates offered here, which were originally published under the title “Two Systems of Astronomy”. For example, Frost’s anti-Newtonian comment on plate 6 reads: “This diagram will show that if the Earth revolves round the Sun, as the Solar System states, then it will necessarily follow that the Earth will differ in its position with the Sun and any given fixed star on its equator, every day, throughout the whole year. Now consider is it so? If it is not so, then it will make much in favour of the Holy Scriptures, that the Sun revolves round the Earth”. The origins of the sect lie in the religious ferment of the Civil War period. In 1651-2 London tailor John Reeve (1608-1658) and his cousin Lodowick Muggleton (1609-1698) announced themselves to be the, two witnesses