Description
Constellations are named in large capital letters but without indication of boundaries. The stars are shown as variously sized dots, circles, and stars according to order of magnitude, some named, some identified with Greek letters. The Equator is graduated in 24 sections, each 0 to 60 degrees; the Ecliptic is graduated to 360 degrees and showing the months instead of being numbered from 0 to 30 within each zodiac sign as on older globes; the Galactic Circle is graduated to 360 degrees. Black stars, lines and lettering are printed on a cream-colored ground. North Pole of Ecliptic, South Pole of Ecliptic, North Pole of Galaxy and South Pole of Galaxy are labeled.
The stars are mapped according to a system known as the Besselian Epoch 1950.0, which means their positions refer to the equator and equinox of 1950, a century later than the epoch of most of the available globes in the 1920s. Because the sun’s apparent motion is not completely regular and owing to gravitational interactions between the Earth and other bodies in the solar system, the celestial equator changes over time and so do the positions of stars relative to the ecliptic (the apparent path of the Sun through the year). To more precisely report the position of an astronomical body, astronomers qualify the coordinates with a date, or epoch. Specifying the epoch defines the coordinate system that is being used. In 1984, astronomers moved to a new system; current star maps use the Julian Epoch 2000.0.
In 1927 John C. Duncan and Leah B. Allen described the globe in a paper published in Publications of the American Astronomical Society. They explain that they designed it after not finding a suitable globe on the market for the teaching of elementary astronomy that was “free from distortion, but more especially for solving elementary problems in spherical astronomy.” They chose the Besselian Epoch to locate the stars. star symbols are arranged on a logarithmic scale. To keep the globe at a practical size for use at desks by individual students, they chose eight inches in diameter, Further, they included only about 400 stars and omitted traditional constellation figures to keep the design uncluttered yet useful for practicing calculations. In addition, their article describes the rationale for other design features (see References below for online link).
Oval cartouche: Duncan’s Eight-Inch/ CELESTIAL GLOBE/Showing the positions of the principal/Stars and Circles of Reference for the/ EPOCH OF 1950.0/ By John C. Duncan, Professor of Astronomy/ and/Leah B. Allen, Instructor of Astronomy/ Wellesley College/ Copyright, 1924, by/ Rand McNally & Company/ Made in U S A.
Additional Legend on Horizon Band: “EASTERN SCIENCE SUPPLY CO. P.O. BOX 1414, BOSTON, MASS., U.S.A.”
Read more about Rand McNally in our Guide to Globe Makers.
Condition: Generally very good with the usual overall light toning, handling, wear. Few minor abrasions restored. Some light oxidation to metal on horizon band. Stand very good with the usual wear and oxidation.
References:
Duncan, John C. and Leah B. Allen. “A New Celestial Globe for the Use of Students.” in Joel Stebbins, ed. Publications of the American Astronomical Society. Vol. 5. 1927. pp. 145-146. Online at: http://articles.adsabs.harvard.edu/full/seri/PAAS./0005//0000161.000.html (25 October 2021).
