ie HERSCHEL'Schen Beobachtungen in der
Ausfuehrlichkeit in welcher sie, verschiedenen Andeutungen zufolge,
_handschriftlich_ vorhanden sind, veroeffentlicht wuerden. Es schliesst
sich dieser Wunsch in Betreff der Nebelflecken lebhaft an den an,
welcher, schon vor einem Jahrzehnt nach Veroeffentlichung der 400 noch
unedirten _star-gauges_ von gewichtigerer Seite her geaeussert wurde."
In this all must agree who have a knowledge of the direction in which we
must look for advances in the difficult and important questions of the
distance, the motions, and the changes of the nebulae. Almost the only
aid to be looked for from the older observations must come from such
diagrams, and we may safely say that the publication of this priceless
material, just as it stands, would carry our exact data back from 1833
to 1786, or no less than forty-seven years.

[37] Long after HERSCHEL had abandoned this idea, it continued
current among astronomers. The successes of Lord ROSSE'S telescope
perpetuated to the middle of the nineteenth century an erroneous view
which HERSCHEL had given up in 1791.

[38] These have never been re-observed. They should be sought
for with a powerful refractor, taking special precautions against the
illumination of the field of view from neighboring bright stars.
HERSCHEL'S reflectors were specially open to illusions produced in this
way. His observations probably will remain untested until some large
telescope is used in the way he adopted, _i. e._, in sweeping.

BIBLIOGRAPHY.

I.--LIST OF THE PUBLISHED WRITINGS OF WILLIAM HERSCHEL ON ASTRONOMICAL
SUBJECTS.

[In chronological order.]

_N.B.--In general, translations and abstracts of those which appeared
in periodicals are not noticed here. I have made exceptions in the
more important cases._

[Solution of a prize question. _See_ this book, page 46.]
_Ladies' Diary_, 1779.

Astronomical observations on the periodical star in _Collo Ceti_.
_Phil. Trans._, 1780, p. 338.

Astronomical observations relating to the mountains of the moon.
_Phil. Trans._, 1780, p. 507.

Astronomical observations on the rotation of the planets round their
axes, made with a view to determine whether the earth's diurnal motion
is perfectly equable.
_Phil. Trans._, 1781, p. 115.

Accoun