we should be able to compute astronomical ephemerides from a
single uniform and consistent set of astronomical data. I hope, in
the course of years, to render this possible.

When our ephemeris was first commenced, the corrections applied to
existing tables rendered it more accurate than any other. Since
that time, the introduction into foreign ephemerides of the
improved tables of Le Verrier have rendered them, on the whole,
rather more accurate than our own. In one direction, however, our
ephemeris will hereafter be far ahead of all others. I mean in its
positions of the fixed stars. This portion of it is of particular
importance to us, owing to the extent to which our government is
engaged in the determination of positions on this continent, and
especially in our western territories. Although the places of the
stars are determined far more easily than those of the planets,
the discussion of star positions has been in almost as backward a
state as planetary positions. The errors of old observers have
crept in and been continued through two generations of
astronomers. A systematic attempt has been made to correct the
places of the stars for all systematic errors of this kind, and
the work of preparing a catalogue of stars which shall be
completely adapted to the determination of time and longitude,
both in the fixed observatory and in the field, is now approaching
completion. The catalogue cannot be sufficiently complete to give
places of the stars for determining the latitude by the zenith
telescope, because for such a purpose a much greater number of
stars is necessary than can be incorporated in the ephemeris.

From what I have said, it will be seen that the astronomical
tables, in general, do not satisfy the scientific condition of