During the late eighteenth and early nineteenth centuries, the American Philosophical Society regularly received letters, and occasionally full blown manuscripts, from members of the public regarding their ideas on science or technology. In 1829, Edward Mulhern of Philadelphia submitted a manuscript on terrestrial magnetism that he felt had implications for navigation. Little is known about Mulhern other than that he died before 1833. Mulhern's "Dissertation on the doctrine and principles of magnetism &" is an attempt to work through some fundamental issues in terrestrial magnetism, including the relative orientation and positions of the geographic and magnetic poles, with an eye toward their impact on navigation. The APS Minutes for April 15, 1833, read: "An application from Alex Mulhern to have returned to him a paper on the 'doctrine of Magnetism' laid before the society by his deceased father, was received and the Librarian was directed to return the same.'"

Included in this volume are short treatises on military topics, such as fortification and geometry, and military discipline; an account of campaigns (1689-1697) with the Royal Regiment of Foot in Ireland fighting the Williamite War between King James II and King William III, an account of campaigns under Prince Eugene of Savoy, with lists of troops; a section entitled "Un traittes touchant les conquètes quon pouroit faire en Amerique sur la maison de Bourbon au cas que la querre devienne generale et qui seules peuvent retablir lequilibre de l'Europe;" and lists of imperial regiments. Volume describes campaigns that took place during the successive reign of William of Orange, Queen Anne, George I and George II. British officers of note are John Lindsay, 20th Earl of Crawford and John Churchill, Duke of Marlborough.

The papers of the Italian natural philosopher and electrician, Giambatista Beccaria (1716-1781) contain letters to Benjamin Franklin, Joseph Banks, Laura Bassi, Gian Francesco Cigna, and others on a variety of scientific topics, including atmospheric and terrestrial electricity, the aurora borealis, earthquakes, meteorology, and phosphorescence. In addition to Beccaria's epistolary essays, the collection includes several journals of meteorological observations and notes for Giovanni Eandi's biography of Beccaria.

The correspondence is principally to Zaccheus Collins (1810-1840), with bills, receipts, and notes on Rafinesque vs. Parker; letters from Collins, L.A. Tarascon, Lewis C. Beck, John Torrey, and Charles W. Short (1817-1835); and miscellaneous correspondence and documents relating to Rafinesque vs. Parker, with an account of the Felician Society of Feliciana County, Illinois (1820). The writings are chiefly on botanical topics, and include notes and essays on Indians, Blacks, grapes and wine-making, banking, and speculation. Rafinesque's growing interest in Indian antiquities, linguistics, and history is apparent in letters after 1820. There is an account of Rafinesque's scientific travels in North America and southern Europe (1800-1832), and a bibliography. The botanical notes include descriptions of specimens collected by Lewis and Clark, Patrick Gass, and Henry Muhlenberg.