Astronomy Sitter, Willem de Album on the occasion of de Sitter's 25th anniversary as professor at the University of Leiden. With 1 sign. Watercolour by J.M. Graadt van Roggen with view of the observatory of Leiden University (ca. 25 x 36 cm) and ca. 200 signed mounted cards with signatures of colleagues and friends. Cards with signatures of colleagues and friends. Leiden, 1933. 23 vols. Landscape fol. master binding in leather (sign. Cris Agterberg (1883-1948)) with a coloured coat of arms embossed in relief on the front cover in a 2-piece cloth case with covers covered in leather with embossed coat of arms and anniversary dates (these somewhat rubbed). With mounted hs. Dedication on pastedown: "Aan Dr W. de Sitter aangeboden op den zeoden October Regentien handered drie en deestig by gelegenheid van zyn Vuf en twintig Jarig Jubileum als Hoogleeraar aan de Universiteit te Leiden". - Contains signatures (arranged from A-Z) of famous astronomers, astrophysicists and others from Sitter's working group, his scientific network and his friends, including Albert Einstein, Giorgio Abetti, Walter S. Adams, Henry Deslandres, Dyson and Edward A. Milne, Sir Arthur Eddington, Ejnar Hertzsprung, Milton S. Humason, August Kopff, F.K. Küstner, George Lemâitre, Bertil Lindblad, J.H. Oort, Antonie Pannekoek, Harlow Shapley, Emile Picard etc. - Willem de Sitter (1872-1934) was a Dutch mathematician, astronomer and cosmologist who developed theoretical models of the universe based on Albert Einstein's general theory of relativity. - Extremely well-preserved, splendid copy. Astronomy - Album on the occasion of de Sitter's 25th anniversary as professor at the University of Leiden. With 1 sign. watercolour by J.M. Graadt van Roggen with view of the observatory of the University of Leiden (approx. 25 x 36 cm) and approx. 200 signed mounted small cards with signatures of colleagues and friends. Master binding in leather (signed Cris Agterberg (1883-1948)) with a coloured coat of arms embossed in relief on the front cover in a 2-piece cloth case with covered in leather with embossed coat of arms and anniversary dates (these somewhat rubbed). - With mounted dedication on vellum: "Aan Dr. W. de Sitter aangeboden op den zeoden October Regentien handered drie en deestig by gelegenheid van zyn Vuf en twintig Jarig Jubileum als Hoogleeraar aan de Universiteit te Leiden". - Contains signatures (arranged from A-Z) of famous astronomers, astrophysicists and others from Sitter's working group, his scientific network and his friends, including Albert Einstein, Giorgio Abetti, Walter S.Adams, Henry Deslandres, Dyson and Edward A. Milne, Sir Arthur Eddington, Ejnar Hertzsprung, Milton S. Humason, August Kopff, F.K. Küstner, George Lemâitre, Bertil Lindblad, J.H. Oort, Antonie Pannekoek, Harlow Shapley, Emile Picard etc. - Willem de Sitter (1872-1934) was a Dutch mathematician, astronomer and cosmologist who developed theoretical models of the universe based on Albert Einstein's general theory of relativity. - Very well preserved, splendid copy. * This work is taxed. There is a 23.95% surcharge on the hammer price and 7% (books only) or 19% VAT on the final invoice amount in the European Union. This work is subject to the regular margin scheme. There is a 23.95% buyer's premium on the hammer price and 7% (Books only) or 19% VAT on the final invoice amount in the European Union. 7500