ta] = -2 deg. and
[delta] = -23 deg. by SCHOeNFELD, according to much the same plan, but with a
larger instrument (aperture 159 mm, focal length 1930 mm, magnifying
power 26 times). The observations were made in the years 1876 to 1881
and include 133659 stars.[8]

The positions in B. D. are given in tenths of a second in right
ascension and in tenths of a minute in declination.

20. _The Cape Photographic Durchmusterung_[9] (C. P. D.). This embraces
the whole southern sky from -18 deg. to the south pole. Planned by GILL, the
photographs were taken at the Cape Observatory with a DALLMEYER lens
with 15 cm. aperture and a focal-length of 135 cm. Plates of 30 x 30 cm.
give the coordinates for a surface of 5 x 5 square degrees. The
photographs were taken in the years 1885 to 1890. The measurements of
the plates were made by KAPTEYN in Groningen with a "parallactic"
measuring-apparatus specially constructed for this purpose, which
permits of the direct obtaining of the right ascension and the
declination of the stars. The measurements were made in the years 1886
to 1898. The catalogue was published in three parts in the years 1896 to
1900.

The positions have the same accuracy as in B. D. The whole number of
stars is 454875. KAPTEYN considers the catalogue complete to at least
the magnitude 9m.2.

In the two great catalogues B. D. and C. P. D. we have all stars
registered down to the magnitude 9.0 (visually) and a good way below
this limit. Probably as far as to 10m.

A third great Durchmusterung has for some time been in preparation at
Cordoba in Argentina.[10] It continues the southern zones of SCHOeNFELD
and is for the present completed up to 62 deg. southern declination.

All these Durchmusterungs are ultimately based on star catalogues of
smaller extent and of great precision. Of these catalogues we shall not
here speak (Compare, however, Sec.23).

A great "Durchmusterung", that will include all stars to the 11th
magnitude, has for the last thirty years been in progress at different
observatories proposed by the congress in Paris, 1888. The observations
proceed very irregularly, and there is little prospect of getting the
work finished in an appreciable time.

21. _Star charts._ For the present we possess two great photographic
star charts, embracing the whole heaven:--The _Harvard Map_ (H. M.) and
the _FRANKLIN-ADAMS Charts_ (F. A. C.).

_The Harvard Map_, of which a copy (or more correctly two copies) on