Plate, four figures showing the catadioptric telescope and Saturn by I [John] Sturt Four figures engraved by John Sturt. Figures 1-3 show the various features of the catadioptric telescope and figure 4 shows Saturn as it was seen through the telescope in June of 1720. Subject: Astronomy / Scientific instruments Published in Philosophical Transactions as 'An account of a catadioptrick telescope, made by John Hadley, Esq; F. R. S. with the description of a machine contriv'd by him for the applying it to use'. [1723]