Portrait mezzotint print from engraving of Phelps Thomas and Bartlett John, 1778

Portrait mezzotint print of Phelps Thomas, made by Watson James, Printed & Published March 14th 1778 by Bretherton James No.134 New Bond Street, London, ; 45x31cm., image platemark 35.3x27.8cm., text platemark 7x27.7cm, frame 57.5x42.5x2cm. Image plate cut at bottom, figures placed on globe and regulator, inscription added beneath on separate plate. Pull trimmed to platemarks. Watermark: IHS (similar to Heawood 2997). Phelps stands in observatory at Shirburn Castle, seat of Parker George 2nd Earl Macclesfield, looking through transit telescope. Bartlett, his assistant, perched on observer's chair frame, prepares to record. Foreground, celestial globe; background L, telescope with altazimuth mounting on braced tripod stand; R, astronomical regulator. Phelps Thomas(1694-) began as a stableman for Parker George, President of the Royal Society (1952-1764) and from 1742 became Observer in the Earl's Observatory. He was the first person in England to detect the great comet of 1743. Barlett John (1724-) was originally a shepherd and became the Assistant Observer in the Earl's Observatory

This portrait formed part of the Bennet Woodcroft Bequest, which was among the founding collections of the Science Museum. Woodcroft had developed a 'National Gallery of Portraits of Inventors, Discoverers and Introducers of the Useful Arts’ combining gifts, loans and purchases of portraits, while acting as the first curator of the Patent Museum.