21. The observatory, University of Minnesota Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–June 1907] Institution: Anna Maria College
22. Observatory, Vassar College, Poughkeepsie, N. Y. Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
23. Observatory, Vassar College, Poughkeepsie, N. Y. Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
24. Observatory, Washburn College, Topeka, Kan. Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–June 15, 1914] Institution: Anna Maria College
25. Observing station, High Altitude Observatory, University of Colorado Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
26. Perkins Observatory, O.W.U., Delaware, Ohio Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
27. The Ritter Observatory & Planetarium Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
28. Student Union, College of Wooster, Wooster, Ohio Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–January 24, 1953] Institution: Anna Maria College
29. Topped by a meteorological tower and astronomical observatory dome, Davis Hall at Northern University in DeKalb overlooks a man-made lagoon that serves as a scenic... Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1965–1996] Institution: Anna Maria College
30. The University of Chicago Yerkes Observatory Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
31. The University of Chicago Yerkes Observatory Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
32. The University of Chicago. Yerkes Observatory, Williams Bay, Wis. Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–July 25, 1908] Institution: Anna Maria College
33. The University of Michigan's 1854 Detroit Observatory Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
34. The University of Texas McDonald Observatory's 107-inch telescope Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
35. Whitin Observatory. Wellesley College Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
36. Yerkes' Observatory, Lake Geneva, Wis. Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–August 8, 1914] Institution: Anna Maria College
37. The Yerkes Observatory of the University of Chicago, William Bays, Wisconsin Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
38. 100 inch telescope dome, Mt. Wilson Observatory Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–October 2, 1936] Institution: Anna Maria College
39. 100 inch telescope, Mt. Wilson Observatory, largest in U.S.A. Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
40. 100" reflecting telescope Mt. Wilson Calif. Format: Postcards/Cards; Photographs Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College