Astronomy: Thomas Phelps (left) and John Bartlett making astronomical observations in the observatory of the Earl of Macclesfield, Oxfordshire. Mezzotint by J. Watson, 1778.

Phelps and Bartlett were respectively observer and assistant observer in the observatory of George Parker, 2nd Earl of Macclesfield, at Shirburn Castle, Oxfordshire: Phelps was originally a stable-boy in the Macclesfield household, Bartlett a shepherd. "Phelps and Bartlett are shown in the Shirburn observatory's transit room, with Phelps observing through the 5-foot transit telescope, by Jonathan Sisson, fixed to supporting pillars. He is steadying himself by leaning on the back of an observing chair. Behind Bartlett is an astronomical regulator, an accurate observatory clock, by George Graham. To the left is an equatorially-mounted, unfixed telescope, probably by Dollond, and in the right foreground is a celestial globe."--online catalogue of the National Maritime Museum, Greenwich, accessed 29 April 2013