Institution.

Aperture in Inches.

Focal

Length in

Feet.

Date of Erection.

Yerkes Observatory, Wisconsin, U. S. A.......................

40.0

62.0

1897

Lick Observatory, California, U. S. A.................

36.0

57.8

1888

Lick Observatory, California, U. S. A...................

33.0

49.2

National Observatory, Meudon.........................

32.5

53.0

1891

Astrophysical Observatory, Potsdam....................

31.1

39.4

Bischoffsheim Observatory, Nice....................

30.3

52.6

1889

Imperial Observatory, Poulkova.....................

30.0

42.0

1882

National Observatory, Paris..................

28.9

Royal Observatory, Greenwich....................

28.0

28.0

1894

Imperial Observatory, Vienna.....................

27.0

34.0

1894

Royal Observatory, Greenwich...................

26.0

26.0

1897

Naval Observatory, Washington.........................

26.0

32.5

1871

Leander McCormick Observatory, Virginia, U. S. A.................

26.0

32.5

1874

Cambridge University Observatory..................

25.0

1868

National University, Meudon.................

24.4

52.2

1891

Harvard College, Cambridge, U. S. A........................

24.0

11.3

1894

Royal Observatory, Cape of Good Hope....................

24.0

22.6

1897

Lowell Observatory, Mexico...................

24.0

31.0

1895

National Observatory, Paris.........................

23.6

59.0

1889

Halstead Observatory, Princeton, U. S. A......................

23.0

32.0

1881

Etna..........................

21.8

Buckingham Observatory...........................

21.2

M. Porro, Private Observatory; Italy..................

20.5

Chamberlin Observatory, Colorado, U. S. A.......................

20.0

28.0

1891

Manila Observatory, Philippines.....................

20.0

1892

Astrophysical Observatory, Potsdam........................

19.7

41.2

Imperial Observatory, Strassburg.....................

19.1

23.0

1880

Milan Observatory, Italy........................

19.1

23.0

North-Western Observatory. Illinois, U. S. A........................

18.5

27.0

1863

Dearborn Observatory........................

18.5

National Observatory, La Plata.....................

18.1

29.5

1890

Lowell Observatory, Mexico.......................

18.0

26.3

1894

Flower Observatory, Philadelphia, U. S. A...................

18.0

1896

Vander Zee Observatory.....................

18.0

Royal Observatory, Cape of Good Hope.........................

18.0

22.6

1897

- Knowledge Diary and Scientific Handbook.