COLLECTION OF DON OLSON p OBSERVATORY TOWER Through an arch of the Hôtel de Cluny in Paris, we see the tower supporting Messier's observatory, from which he discovered comets, clusters, and nebulae. This portrayal, drawn by Frederick Nash and engraved by John Pye, appeared in Picturesque Views of the City of Paris and its Environs (London, 1823). s k y a n d t e l e s c o p e .c o m * JUNE 2017 35http://www.skyandtelescope.com