Elger: The Moon (1895)(glossary entry)
Thomas Gwyn Elger's The Moon: A Full Description And Map Of Its Principal Physical Features is one of the little known classics from the golden age of visual lunar observing. Because it is in the public domain, and freely available through the kind services of Project Gutenberg and Steve Ridgway (who transcribed it electronically), Chuck has chosen to use it to add a historical perspective to the descriptions of lunar features on the-Moon Wiki. Elger was a careful observer, and if nothing else it gives a good impression of what can be observed by eye, through a small telescope, from Earth. In recognition of his accomplishments, a 21-km diameter crater on the Moon's nearside is named after him.
- Two copies of Elger can also be viewed as a searchable on-line "flip-book" or PDF download at the Internet Archive: Copy 1 or Copy 2.
In many cases Elger's terminology differs from that in modern use. In particular, Elger wrote his book in an era when the convention for what should be regarded as east and west on the Moon was the reverse of the IAU directions used today. For the-Moon Wiki, the Easts and Wests in most of the entries from Elger have been converted to the modern IAU usage. So if a passage is marked IAU Directions it will be consistent with E being on the Crisium side of the Moon. A few older entries may be in Elger's original reversed E-W format.
You will also encounter a number of terms that are not in common use today. For example:
|walled plain or ring plain
(list to be expanded...)
Also, Elger used what are now antiquated names for a number of the lunar features. Some of these have been replaced by newer names, others have been dropped.
||Mons Gruithuisen Delta|
||Mons Gruithuisen Gamma|
||Mons La Hire|
|OTTO STRUVE A
||reference to the crater Eddington?|
|THE ALTAI MOUNTAINS
|THE HERACLIDES PROMONTORY
|THE LAPLACE PROMONTORY
|THE STRAIGHT RANGE
|THE STRAIGHT WALL
|THE TENERIFFE MOUNTAINS
|VASCO DE GAMA
||Vasco da Gama|
Several names Elger used do not match any currently approved name in the IAU Nomenclature. Those features, of course, still exist, they are just no longer named:
THE HERCYNIAN MOUNTAINS
THE HUMBOLDT MOUNTAINS
THE NORTH POLAR RANGE
THE PERCY MOUNTAINS
THE SILBERSCHLAG RANGE
THE SINUS IRIDUM HIGHLANDS
THE STAG'S-HORN MOUNTAINS
Finally, it appears that Elger did not stick strictly to the convention of referring to satellite craters with Roman letters and elevations (peaks) with Greek letters -- a practice that was used by many of his contemporaries. Although he frequently did use Greek letters in this way, his references to something like Fontinelle A may still be to a peak near Fontenelle rather than to the modern lettered crater of that name.
- Full Elger text with E-W directions in modern style:
- Fielder, Gilbert. 1963. Some Lunar Studies by T. G. Elger. Sky and Telescope Vol. 15, No. 4 (May issue), pp. 248-251. article illustrated by drawings made by Elger between 1884 and 1896, with particular emphasis on his depiction of "lineaments"