Our Collection

Armillary Spheres

Armillary spheres were used well into the seventeenth century to teach the concepts and coordinate systems of spherical astronomy. The Earth is at the center, and rings represent the horizon, equator, tropics, ecliptic, and important colures. The "cage" as a whole rotates around the axis of the celestial poles. An armillary can be used to demonstrate, for example, the azimuths and angles at which the sun rises and sets at different times of the year. Armillary spheres sometimes incorporate models explaining the motion of the Sun, the Moon, or other planets.

Image to the right: This armillary sphere was made in 1562 by Gualterus Arsenius in Louvain, Belgium. [M-1]

See more of our armillary spheres by searching the term in our collections database.

Astrolabes

The front side of a typical astrolabe displays a stereographic projection of the northern portion of the celestial sphere, with the North Pole at the center and the Tropic of Capricorn at or near the edge. Also present are altitude circles for the terrestrial latitude to which the instrument was designed. The altitude circles converge on the zenith, which appears slightly above the central pin of either of the astrolabes shown here.

Image to the above right: An Eastern astrolabe (with inscriptions in Arabic) from Baghdad, this instrument is signed and dated to the year 525 of the Hegira, which is A.D. 1131 in our calendar. It is the oldest instrument in the Adler's collection. [A-84]

Most astrolabes came with a set of plates bearing altitude circles for different latitudes.

A fretwork "rete" bearing pointers for prominent stars can be rotated to align those pointers to the coordinates of the stars at any particular time. Once this is done the coordinates of other stars can be read directly off the plate, and the time of day can be read from a scale on the rim of the astrolabe. The rete also contains a prominent ecliptic circle, allowing the position of the sun to be used along with those of the stars.

Image to the above right: Western astrolabe has inscriptions in Latin and is from 14th-century England. It features a cluster of three star pointers in the shape of a dog's head. [M-26]

The back of the instrument bears a sighting device or "alidade" that is normally used to measure the altitude of the sun or a star. Once this altitude is known, the rete can be rotated to the correct position.

See more of our astrolabes by searching the term in our collections database.

Celestial Globes

Celestial Globes represent the positions of stars on the celestial sphere, and usually bear fanciful depictions of the constellations.

Image to the right: W-274. A small (2 3/4-inch diameter) pocket globe made by J.B. Homann around 1715. Within the outer case is a map of the heavens and a terrestrial globe. The terrestrial globe itself opens to reveal a tiny armillary sphere (not shown).

Navigational Instruments

The mariner's astrolabe was once a common navigational instrument, used to measure the altitude of the sun or a star. It was usually made of thick metal and pierced with large openings, for stability while making observations in the wind.

Image to the right: This Portuguese instrument is dated 1616, and is one of only a few dozen in the world that have survived (apparently most were discarded, or lost at sea). [A-275]

The Adler has a major collection of navigational instruments, dating from the sixteenth through the twentieth centuries. The collection is particularly strong in octants, sextants, and quadrants.

Orreries

Orreries or planetaria are mechanical models that show the motion of planets around the Sun, the Moon around the Earth, or both. There is a good deal of ambiguity in the names used for these mechanisms. Strictly speaking, A-156 is a tellurian, since it shows only the earth and moon. Orreries, and particularly grand orreries such as A-61 and DPW-1, are usually more complex and accurate than mechanisms merely termed "planetaria."

Image to the top right: A grand orrery, about 39" in diameter, this was made by Thomas Heath in London around 1740. After the discovery of Uranus in 1781, the owner had an outer ring (which does not move) added to show the new planet. For this photograph the mechanism was raised out of its cabinet. [DPW-1]

Image to the lower right:This curious object is probably the first orrery ever made. It was made by George Graham in London between 1704 and 1709, is driven (very slowly) by clockwork, and shows the rotation of the Earth around the Sun and that of the Moon around the Earth. [A-156]

The "planetarium" as a simple orrery should not be confused with the "planetarium" as a domed theater on which the heavens are depicted!

Sundials

Almost every conceivable shape has been adapted for use as a sundial by instrument makers. For most of history sundials have been the most reliable and accurate way of telling time, useful whenever the sun was visible. After the widespread adoption of mechanical clocks, sundials were still essential—as a means of setting the clock!

Image to the upper right: Multiple-faced wooden polyhedral sundial. This instrument combines many dials: a "skaphe" (bowl) sundial, and numerous vertical and horizontal dials reading in both regular and "Italian" hours. It was probably made in Bologna around 1575. [M-318]

Image to the lower right: A large silver and brass sundial made in Germany around 1650. The design comes from Oronce Fine's book on sundials printed in 1565. It bears 29 gnomons, and really demonstrates the Renaissance mathematician's interest in solving intricate puzzles, rather than any practical application of his knowledge. [M-324]

Surveying Instruments

Surveying instruments such as compasses and theolodites are used to measure angles and elevations. They can be fitted with a great variety of sights to increase the precision of measurement.

"Mathematical instruments" form a loose class that includes drawing instruments, sectors, and rules of all kinds. Small ones are often packed as a set in an ornate case covered in leather, cardboard, shagreen, or a similar material.

Image to the right: A surveyer's compass is used to measure angles with respect to compass bearings. This one is from the mid-eighteenth century. The detail in the image shows the signature "Made by Thomas: Greenough Boston: N: England".

Telescopes

The Adler has a number of large seventeenth-century telescopes (not shown here, but see the image from the Mensing catalog). Early objective lenses had very long focal lengths, due to the as-yet unsolved problems of spherical and chromatic aberration.

Image to the right: This William Herschel telescope closely resembles the one with which Herschel discovered the planet Uranus in 1781. The tube and primary mirror are original; the mount is a modern reproduction of Herschel’s design.

Where is the Dearborn Telescope?

For many years the Dearborn Telescope, the largest telescope in the world in its time, has been one of the most popular exhibits at the Adler Planetarium. The telescope has had an unusually varied career, and has recently returned from a careful, professional facelift, resuming its place in the new Adler.

Signatures

As a tool for specialists interested in makers of scientific instruments, the Adler is pleased to make available a simple but large database of instrument makers, or more precisely of their signatures, a product of many years of research by the late Roderick and Marjorie Webster, longtime curators of the collection of scientific instruments at the Adler. Use the database as a guide to further research, with caution. Most instruments cited in this database are NOT in the Adler collection. We cannot provide further information on instruments not in the Adler collection.

Search the Webster Signature Database.

Works on Paper

The Works on Paper Collection contains about 650 individual maps, prints, and book plates featuring astronomical illustrations. Strengths of this collection include comet and eclipse broadsides, portrait prints, and celestial charts.

See examples of our Works on Paper collection by searching our database.

Rare Books Collection

The Rare Book Collection contains over 3000 volumes, including over a dozen incunabula (books printed before 1500). The rare books cover a wide range of topics about the history of astronomy and scientific instruments. This collection includes all of the most important historical celestial atlases, as well as many other atlases. It also contains a large number of books on comets, early works on instruments, and astronomical and cosmological texts and tables. Other works include treatises on mathematics and its practical applications, works on optics, physics, astrology, geography, and navigation, and early encyclopedias and dictionaries.

Books are catalogued in OCLC. You can find books listed in OCLC's free WorldCat database (worldcat.org). In libraries where OCLC's FirstSearch is available, you can limit your WorldCat search to the Library Code "AP$". Interlibrary loan is not available.

Modern Books and Periodicals

The Webster Institute at the Adler holds a collection of modern books and periodicals relating to historic scientific instruments and the history of astronomy. Books are catalogued in OCLC. You can find books listed in OCLC's free WorldCat database (worldcat.org). In libraries where OCLC's FirstSearch is available, you can limit your WorldCat search to the Library Code "AP$". Interlibrary loan is not available..

Mensing Collection

The Mensing collection is the heart of the Adler's Antique Instrument Collection. Its core was assembled by Raoul Heilbronner, a German dealer in Paris around the beginning of the twentieth century. When war broke out in 1914, Heilbronner hurriedly returned to Germany. His collection was confiscated by the French government and sold to Antoine W. M. Mensing. Mensing added a number of other items to the collection and in due course sold the entire instrument collection to Max Adler.

Image to the right: Plate 1 from the 1924 catalog of the Mensing Collection. This old photograph shows some of the armillary spheres, sundials, astrolabes, and telescopes purchased by Max Adler and donated to the Adler Planetarium at its founding in 1930.

Webster Institute Publications / Adler Collections

The Webster Institute has produced several publications about the Adler's Collections. Learn more on our Publications Page.