Written by William Alexander at Basking Ridge, New Jersey, March 27, 1773, this essay appeals to the American Philosophical Society to collect and publish astronomical observations. It was sent to the American Philosophical Society, where it was duly read in May 1773.

The Smith-Houston-Morris-Ogden Family Papers document the history of the Houston, Smith, Ogden, Morris and allied families, beginning in the late 17th century, and continuing through to near the end of the 20th. Among the many treasures in this vast collection are the papers of Pennsylvania Railroad executive Henry Howard Houston (1820-1895), his son, Samuel Frederick Houston (1866-1952), and of Pennsylvania attorney and treasury official, William Meredith (1752-1816). Although the collection contains a great deal of interest with respect to land speculation, commerce, and trade emanating from Philadelphia, the bulk of the Smith Family Papers consists of personal and family correspondence and other papers. Among the largest and most interesting bodies of papers are those of L.M.C. Smith and Eleanor Houston Smith, daughter of Samuel F. Smith. These document the family's progressive attitudes regarding and resource conservation, historic preservation, and their social activism. This very large collection includes much material that is not itemized below.

James Burd (1726-1793) was well-known in colonial Pennsylvania through his role in the French and Indian War, as well as his connections to many of the colony's leading families (most notably the Shippen family). Initially starting out as a merchant in Philadelphia, Burd became increasingly involved with colonial affairs after moving to Lancaster County with his family in 1752. It would be on the frontier where Burd would make his mark first as a soldier, and later as a magistrate. The Burd-Shippen Papers consist mainly of letters and business documents sent to James Burd, with the bulk of the collection relating to the French and Indian War, 1754-1763, in which Burd served as an officer commanding troops at Fort Augusta and elsewhere. The collection reflects all aspects of Burd's life in Pennsylvania as a merchant, soldier, and magistrate; as well as his involvement with the Shippen family professionally and personally. Intermixed with items sent to Burd are receipts to his wife Sarah Shippen Burd, and correspondence between Edward Shippen and James Hamilton regarding land matters and Indian affairs in Lancaster.

These letters and papers include ten small volumes of letterbooks (1752-1781), and ca. 100 pieces of correspondence with Joseph Shippen (1750-1778). Topics discussed are business in Philadelphia and Lancaster, provincial politics, army supply in the French and Indian War, land purchases and speculation, housebuilding, and family affairs.

A collection of business and personal papers of three generations of the prominent Philadelphia Jewish family from 1750-1974. Business records include trade and land transactions (some in Yiddish) of the Gratz brothers, Barnard and Michael (1750-1804) with the business continued by Michael's sons: Simon, Hyman, Joseph, Jacob, and Benjamin (1791-1861). Personal correspondence are primarily letters to Rebecca Gratz from her sisters Rachel and Sarah (1795-1867) with later correspondence to Rachel's children: Horace and Sara Moses (1832-1879). Contains a small group of French letters related to Napoleon III, collected by family member Miriam Fox, and some heirloom artifacts.