Columbia subject headings:
Astronomical observatories--Washington (D.C.)--History--Congresses.
United States Naval Observatory--History--Congresses.
Harvard subject headings:
Astronomical observatories--Washington (D.C.)--History--Congresses.
United States Naval Observatory--History--Congresses.
Princeton subject headings:
Astronomy--United States--Congresses.
United States Naval Observatory--History--Congresses.