CATALOGUES OF ECLIPSES: AND THEIR CALCULATION.
This must of necessity be a brief chapter, so far as mere lines of text
are concerned, but it will not on that account be unimportant. It will
be evident to the reader that many more eclipses of interest have
happened, and will happen, than it has been possible to speak of in
these pages. Accordingly, as it is one of the main objects of this
series of volumes to create a thirst for knowledge, to be satisfied by
the study of other and bigger volumes, it will be desirable to furnish a
list of some of the various books and publications, in which eclipses
will be found catalogued or described in detail, so that readers
desirous of pursuing the matter further, may possess facilities for
doing so.
By far the most complete and comprehensive catalogue of solar eclipses
is that prepared some years ago by an Austrian astronomer, the late
Theodore Von Oppolzer of Vienna, and published under the title of _Canon
der Finsternisse_, in the Memoirs of the Imperial Academy of
Sciences.[144] This work supplies approximate calculations of about 8000
eclipses of the Sun, for a period of more than 3000 years, from November
10, 1207 B.C. (Julian Calendar), to November 17, 2161 A.D. (Gregorian
Calendar). There are appended 160 charts, of all the principal
eclipses; but as the charts only exhibit the beginnings, middles, and
ends of the eclipses dealt with, they are frequently misleading, because
the intermediate lines of path are, in many cases, more or less
considerably curved.
Another very important and comprehensive catalogue of eclipses, solar
and lunar together, will be found in the well-known French work, _L'Art
de vérifier les Dates_,[145] compiled by a member of the religious order
of St. Maur. One volume of this famous work contains eclipses from the
year 1001 B.C. to the Christian Era, whilst another volume gives a
similar catalogue from the year 1 A.D. to 2000 A.D. The other volumes
deal with chronological matters only. Although not strictly a work of
extreme astronomical exactness, yet _L'Art de vérifier les Dates_ stands
unrivalled as a record not only to subserve the purpose indicated by its
title, but of the bare facts of the eclipses which have happened during
the period of 3000 years stated above.
There has not been much done in England in the way of publishing eclipse
records or tables, past or future, but in the _British Almanac and
Companion_ for 1832 there is given a catalogue, which was useful in its
day, of eclipses, then future from 1832 to 1900, omitting, however,
solar eclipses hardly visible to any inhabited portion of the Earth, and
lunar eclipses where the part of the Moon's diameter obscured was less
than 1/12th.
In by-gone days several attempts were made to gather together in a
tabular or paragraph form the details of eclipses which had happened,
and some of these have been important sources of information for the
guidance of us moderns. Foremost amongst these efforts must be named the
_Almagestum Novum_ of J. B. Ricciolus.[146] This work contains a
catalogue of eclipses observed from 772 B.C. to A.D. 1647, and continued
in tables to A.D. 1700. It is prefaced (pp. 286-8) by a long series of
quotations from classical authors relating to eclipses, some few of
which have already been mentioned in these pages.
Kepler paid much attention to eclipses, and left behind him a large mass
of notes and original observations. These will be found chiefly in his
_Astronomiæ Pars Optica_, c. vii. § 2, originally published at Frankfurt
in 1604. The most convenient and accessible edition of this is to be
found in Frisch's reprint of all Kepler's works.[147]
Tycho Brahe also gathered together from various sources many
observations of eclipses, and combined them with a number of his own,
the whole being published in his _Historia Coelestis_.[148] Tycho Brahe
was a very interesting personage in spite of the fact that he went all
astray on the subject of the system of the Universe, and he well
deserves, what has been given to him, a book[149] all to himself. It is
peculiarly appropriate that I should give him a good word in this little
volume on eclipses, because it was the solar eclipse of Aug. 21, 1560,
which first seriously led him to take up astronomical pursuits, he being
then 14 years of age, and struck with wonder that eclipses could be
predicted.
A vast amount of historical and other information respecting eclipses
will be found in a book, the latinised name of whose author is Sethus
Calvisius. The title of the work is _Opus Chronologicum_.[150] The
historical matter is very much mixed, but the eclipses can be got hold
of through the Index, which is very full. P. Gassendi,[151] a well-known
astronomer of the 17th century, left behind him observations of many
eclipses observed by himself between 1628 and 1655. In a book entitled
_An Introduction to Universal Geography_,[152] one Nicolas Struyck in
the middle of the 18th century published a very full array of eclipse
observations collected with infinite pains from an endless variety of
authors ancient and modern.
In 1757 the well-known James Ferguson reprinted in his
_Astronomy_,[153] but in a very condensed form, all Struyck's eclipses
from 721 B.C. to A.D. 1485. Then he carried on his catalogue to 1800 by
means of the materials furnished by Ricciolus and _L'Art de vérifier les
Dates_. Ferguson also invented a machine for illustrating mechanically
the circumstances of an eclipse. He called it the "Eclipsareon." A full
description is given in his book, mentioned above, but I do not know
whether any such instrument is still in existence, or, if so, where it
is to be found.
Ferguson apologises[154] for the incompleteness of his eclipse
information in the following words:--"I have not cited one half of
Ricciolus's list of portentous eclipses, and for the same reason that he
declines giving any more of them than what that list contains, namely,
that 'tis most disagreeable to dwell any longer on such nonsense, and as
much as possible to avoid tiring the reader. The superstition of the
ancients may be seen by the few here copied. My author further says that
there were treatises written to show against what regions the malevolent
effects of any particular eclipse was aimed, and the writers affirmed
that the effects of an eclipse of the Sun continued as many years as the
eclipse lasted hours, and that of the Moon as many months."
The most comprehensive (indeed almost the only) modern English book on
eclipses is the Rev. S. J. Johnson's,[155] of which frequent use has
already been made in these pages. It contains a vast amount of matter
put together in a condensed form but the references to authorities are
rather defective and deficient. Less comprehensive in one sense yet
exceedingly valuable and interesting as a succinct summary of solar
eclipse knowledge up to the date of 1896 is Mrs. D. P. Todd's excellent
little volume[156] which has been several times quoted on previous
pages. On various occasions in 1890 and following years Professor J. N.
Stockwell contributed to the American _Astronomical Journal_ a number of
papers[157] discussing in a very interesting and exhaustive manner many
of the eclipses recorded by the ancient classical authors. These papers
should be consulted by all who desire to realise the value of eclipse
records in connection with mundane chronology.
The calculation of eclipses is a matter of some interest. It is beyond
the scope of the present work to explain even in outline the methods in
use, but with the aid of the books mentioned below[158] a reader
possessed of the necessary time, mathematical knowledge, and patience,
will be able to pursue this matter as far as his inclination may lead
him. Johnson has found very useful the tables given in the eighth
edition of the _Encyclopædia Britannica_ (Article, "Astronomy") but
strange to say these tables do not appear in ninth edition of that
famous work.
Lalande[159] has given numerous references to eclipses of the Sun during
the 16th, 17th and 18th centuries which may be useful to those who wish
to work at the history of eclipses.
FOOTNOTES:
[Footnote 144: _Denkschriften der Kaiserlichen Akademie der
Wissenschaften_, vol. lii. Vienna, 1887.]
[Footnote 145: There are several editions of this work in
circulation. The first (published in 1783) was in folio volumes,
but the best known edition is in a large number of octavo
volumes published in 1818 and following years. The eclipse lists
will be found in the 1st volumes of the first and second series
respectively. The French astronomer, Pingré, is responsible for
them.]
[Footnote 146: Published at Bononia (Bologna) in 1653.]
[Footnote 147: _Omnia Opera_, vol. ii. pp. 311-16. Edited by Ch.
Frisch. 8 vols. 8vo. Frankofurti-a-M., 1857-60.]
[Footnote 148: A collected edition of Tycho Brahe's works, edited by
"Lucius Barettus," was published at Augustæ Vindilicorum (Augsburg)
in 1666. Lucius Barettus is an anagram for the real name Albertus
Curtius.]
[Footnote 149: J. L. E. Dreyer, _Tycho Brahe: a Picture of
Scientific Life and Work in the Sixteenth Century_.]
[Footnote 150: _Opus Chronologicum._ Francofurti ad Moenum, 1650.]
[Footnote 151: _Astronomica_, vol. iv. Lugduni, 1657.]
[Footnote 152: _Inleiding tot de Algemeene Geographie._ Amsterdam,
1740.]
[Footnote 153: _Astronomy Explained upon Sir Isaac Newton's
Principles._ 2nd ed. 4to, pp. 167-79. London, 1757.]
[Footnote 154: _Astronomy_, p. 178.]
[Footnote 155: _Historical and Future Eclipses._ 2nd Ed., 1896.]
[Footnote 156: _Total Eclipses of the Sun._ Boston, U.S., 1894.]
[Footnote 157: _Astronomical Journal_, vol. x. pp. 25, 185; vol. xi.
pp. 5, 28, 57; vol. xii. p. 121; vol. xiii. p. 73; vol. xv. p. 73;
vol. xvi. pp. 89, 175.]
[Footnote 158: J. Ferguson. _Op. cit._; W. D. Snooke, _Brief
Astronomical Tables for the Expeditious Calculation of Eclipses_,
8vo. Lond. 1852.]