Franz von Paula Gruithuisen (1774− 1852) and the ‘Lost City in the Moon’

In the early hours of the morning of July 12 in the year 1822, Franz von Paula Gruithuisen (1774–1852) turned his small telescope to the Moon. What greeted him at the eyepiece, in the environs of the crater named Schroeter, was nothing short of a revelation. The jumbled terrain, caught under raking illumination, coalesced into a regular arrangement which convinced the astronomer he had discovered evidence that the Moon was inhabited.  Two years later Gruithuisen published a lengthy paper in which he presented many evidences to suggest this. However, it was his initial discovery in 1822, an episode which became known as the ‘City in the Moon’, which has become his most published account. This short paper outlines a similar feature recorded by Gruithuisen and revisited by T.  W.  Webb (1806-1885) in his Celestial Objects for Common Telescopes. Conclusions are drawn from Webb’s account which suggest why this episode, similar in general terms to the ‘City in the Moon’, is not more widely known.

Discovering the ‘Lost City’
In the first edition of Celestial Objects for Common Telescopes, published in 1859, the Rev. T. W. Webb (1806-1885) describes the lunar crater Rhaeticus thus:
‘…an irregular crater, marks exactly the Moon’s equator, and is one of the few spots to which both the Sun and Earth may be vertical. In its interior Gruithuisen [Franz von Paula Gruithuisen] detected one of those regular formations of which he said so much: his figure in the Astronomische Jahrbuch for 1828 represents a somewhat curved line with a little crater at one end and a mound at the other, crossed by four shorter straight lines; as he blamed its inaccuracy, it is not worth copying, but the object should be looked for, especially as its site is so convenient;’

Webb revised the text in later editions with a footnote appended to his description of Copernicus. Here Webb corrected and clarified his entry relating to Rhaeticus as follows: (continued)

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