21. The honeycombed structure of the 200" mirror sets waiting for the thin aluminum coating that will give it its high reflectivity Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
22. Interior of Yerkes Observatory, Williams Bay, on Lake Geneva, Wisconsin Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
23. Interior view of Palomar Mountain Observatory, showing details of world's largest telescope Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
24. Kirkwood Observatory, Indiana University, Bloomington, Indiana Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
25. Largest (200-inch) mirror in the world Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
26. The Loines Observatory of the Maria Mitchell Association of Nantucket Island, Massachusetts Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1968–1996] Institution: Anna Maria College
27. Maria Mitchell memorial and observatory, Nantucket, Mass. Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
28. McDonald Observatory Ft. Davis Tex. Format: Postcards/Cards; Photographs Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
29. McDonald Observatory on Mt. Locke Format: Postcards/Cards; Photographs Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–June 21, 1933] Institution: Anna Maria College
30. McDonald Observatory on scenic drive - Davis Mts Format: Postcards/Cards; Photographs Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–April 18, 1940] Institution: Anna Maria College
31. McDonald Observatory on top of Mount Locke, Davis Mts Format: Photographs Collection: Travel Postcards of Charles Blumsack Date: September 1940 Institution: Anna Maria College
32. Moraine Farm, Dayton, Ohio Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
33. Moraine Farm, Dayton, Ohio - observatory Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
34. Morningside College- Sioux City, Iowa Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
35. Mt. Palomar Observatory, still in the process of building, is soon to become the home of the world's largest telescope--a 200-inch medium that will penetrate stellar... Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: (c) 1939 Institution: Anna Maria College
36. Night time scene of observatory and grave of Dr. Mitchell Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
37. Observatoire de Paris - Grand Equatorial coudé de 0m60 d'ouverture et 18 mètres de distance focale Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
38. Observatoire de Paris - Salle Méridienne Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
39. Observatoire de Paris - terrasse superieure Coupole de l'Equatorial de la Tour de l'Est Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: [ca. 1906–1996] Institution: Anna Maria College
40. Observatory and lake view. St. John's University, Collegeville, Minn. Format: Postcards/Cards Collection: Travel Postcards of Charles Blumsack Date: (c) 1907 Institution: Anna Maria College