In 1877, L.N. observed Mars & created detailed maps of its surface features & 3D Mars globe (diameter 10 cm) produced in small series by J. Lebèque & Co., Brussels, 1892; Notices astronomiques
Brussels Royal Observatory (joined its staff in 1878, publ. in Bulletin mensuel du magnétisme terrestre de l'observatoire royal du Belgique)
instrument makers J. Lebeque & Co., Brussels (for Mars globe) ;