The First Aplanatic Object Glass

Herschel J. F. W. , “On the aberrations of compound lenses and object-glasses”, Philosophical transactions of the Royal Society of London (1821), 222–67, p. 222.

Ibid., 261.

King H. C. , The history of the telescope (London, 1955), 191–2.

South J. , “Results of some astronomical observations …”, Quarterly journal of science, literature and the arts, xiii (1822), 386, note plate v.

See, for example King , op. cit., 192.

Pearson W. , An introduction to practical astronomy (London, 1829), 36.

Encyclopaedia metropolitana, ed. Smedley E. , Mixed sciences, ii (London, 1830), 427.

Private communication from Rev. Edmonds B. B. .