Includes more than 12,000 letters and documents during the time of the Observatory's founder, Percival Lowell.

This correspondence is primarily with George W. Corner, Executive Officer of the American Philosophical Society, concerning Whipple's membership in and contributions to the Magellanic Committee of the APS. This committee awards a medal for the best discovery in navigation, astronomy, or natural philosophy.

Most of this collection is original letters and drafts of Herschel's replies, with some miscellaneous papers other than letters. There are about 400 letters between Herschel and Charles Babbage.

This item, by an unknown author, presents an astronomical sketch of eclipses, some of which could be seen from Philadelphia and Canton, China.

This essay formed the basis of lectures George Howard Darwin delivered before the Royal Institution of Great Britain on January 25, 1889. It was a popular account of a paper he read before the Royal Society the previous November ("On the Mechanical Conditions of a Swarm of Meteorites, and on Theories of Cosmogony," Proc. 45:3-16).

These volumes contain calculations and drawings of an eclipse of the sun, 24 June 1778, and of the moon, 29 May 1779, adjusted to the meridian of Philadelphia. There is also an incomplete duplicate of the calculations for the sun, and a duplicate of the calculations for the moon. An apparently personal reference in the text suggests that Freehauff was a native of Germany.

Included in these papers are letters, memoranda, computations, and tables.

These papers include letters from Admiral C.R. Moorson, correspondence with James Ross and Edward Sabine concerning polar exploration, and a map of the stars near the North Pole.

The 43" tube is fabricated of cast brass sheet. The focal length is 45" and total length of the tube equals 46 1/2" and it is mounted on a mahogany tripod for use in a standing position. The finder is a 9 3/4" telescope with crossed hairs. The control handle for horizontal adjustment is missing, as is part of that for vertical adjustment. The wooden tripod can be used as altazimuth or parallactic mounting so that the telescope might be used for terrestrial or celestial viewing. The wooden, cylindrical, telescope base on top of the tripod is divided into two halves of an angle of 25 1/2° and pivoted at the center on a tapered axis, vertical to the plane of division. When the two halves form a cylinder, the top surface is horizontal and may be used for terrestrial viewing. By turning the top half 180°, the top surface makes an angle of 51° with the horizontal (the latitude of London). These two positions are indicated on the cylindrical bodies by two lines, 180° apart. The lines of marked by two thin ivory strips inlaid in the wood. Marked, "Dollond, London." (Robert P. Multhauf, "Catalogue of Instruments and Models," 1961).

Celestial globe mounted on a four-legged wooden stand. Equator of stand notes months and corresponding astrological signs, as well as measurements affixed on paper. Brass meridian circle. Inscribed: "Britanniarium REGI Augustissimo/GEORGIO TERTIO. Astronomorum Patrono Munificentissimo, Celeberrimo Globum hunc Cælestem, Novam et Emendatiorem Cæti Imaginem, Syder apud Africæ Promontorium Aufrical nuperrime observata, Atq Stellas Catalogi Flamistediami Universas, vere exprimentem. Grati anime et pietatis Monumentum, D. D. Q. Omni cultu et officio devinctissimus G. Adams./Londinin apud G. Adams artificem Regium in vico Fleet Street."

Inscribed: "To the Rev. Nevil Maskelyne, D.D., F.R.S., Astronomer Royal, this new British Celestial Globe. Containing the positions of nearly 6000 Stars, Clusters, Nebulae, Planetary Nebulae, etc. correctly computed and laid down for the year 1800 from the latest observations and discoveries by Dr. Maskelyne, Dr. Hershel, the Rev. Mr. Wollaston, etc., etc. is respectfully dedicated by his most obedient hbl servents [sic] Wm. G.M. Bardin." In addition to the usual constellations, the celestial globe includes others in the extreme southern hemisphere named for the air pump, mariner's compass, chemical furnace, sculptor's apparatus, microscope, painter's easel, clock, telescope, and drawing compass. Also affixed with a paper tag, "Sold by W. & S. Jones, Holborn, London." (Robert P. Multhauf, "Catalogue of Instruments and Models," 1961).

Inscribed: "To the Rt. Honorable Sir Joseph Banks, Bart., President of the Royal Society, this new British terrestrial globe containing all the latest discoveries and communications from the most correct and authentic observations and surveys to the year 1799 by Capn Cook and more recent navigators. Engraved from an accurate drawing by Mr. Arrowsmith, Geographer, is respectfully dedicated by His most obedient serven Wm. H. [partially obliterated] Bardin." Also affixed with a paper tag, "Sold by W. & S. Jones, Holborn, London." (Robert P. Multhauf, "Catalogue of Instruments and Models," 1961).

Mahogany case. Bell-top hood with three beet-shaped wooden finials, the base of the center one being flanked by brackets resembling thorny branches. The dial is 12 1/2" square, of silvered brass. Marked "Duffield, Philada." The movement has a time train of four arbors and is conventional. The deadbeat escapement is located between the plates. An 8-pound pendulum with a pine rod and lens-shaped bob is driven by a crutch wire. It is adjustable but not compensated. (Robert P. Multhauf, "Catalogue of Instruments and Models," 1961).

The sitter faces the viewer’s right in three-quarter view. He has a receding hairline with short, thin, graying hair and a prominent brow, and his right ear is visible. He is dressed in a dark overcoat and white cravat, positioned against a dark, somewhat modulated background.

Portrait with head and shoulders visible to above waist. Body slightly turned right, head facing forward. Figure wears red academic robe, brown coat and waistcoat, blue cravat. Signed "Lazar Raditz" in lower right corner. After ca. 1894 photograph.

Rectangular wood dial covered with paper consisting of two leaves that fold flat. The dial is surrounded by a decorative border with a floral pattern. String gnomon (no longer extant) would attach between the inner surfaces of the two leaves. Exterior top: list of cities in the Americas, Italy, France, Spain, and Germany along with sundial's numerical position. Interior: sundial base and embedded compass (no longer functioning).

Marble portrait bust with bare shoulders and upper chest. The subject has wavy, cropped hair and a stern expression. "D. RITTENHOUSE" inscribed on the base. "DE FACIE PHILADELPHIAE / EX ECTIPO FLORENTIAE / FACIEBAT JOS. CERACCHI / CIDDCCLXXXXIV" incised on verso.

The personal library of Nathaniel Bowditch encompasses works on mathematics, astronomy, and navigation. Among the treasures of the collection are early editions by such scientific luminaries as Galileo, Newton, and LaPlace; numerous treatises on comets and sundials; long runs of scientific periodicals; and, of course, Bowditch's own manuscripts.