The DAS Librarian has initiated a comprehensive survey of astronomers connected to Delaware, along with their telescopes, sundials, instruments, and observatories. This effort spans from the observational traditions of Native American (Lenape) skywatchers, through the celestial navigation practices of 17th-century explorers and settlers from England, Holland, and Sweden, to the work of 18th-century surveyors, teachers, and gentleman astronomers.
The publication of astronomical almanacs in Wilmington during the 18th century—such as those printed by Delaware's first printer, James Adams, who was part of the Franklin & Hall printing network—reflects the early dissemination of practical astronomical knowledge to the public, including calendars, planetary motions, eclipses, and navigational data. In 1769, observations of the Transit of Venus were conducted in Lewes, placing Delaware within the broader international scientific effort to measure the scale of the solar system. Notable among Delaware observers is the Quaker Brandywine miller and mathematician, William Poole (1726–1779), who used a 12-foot refractor in Wilmington to observe the transit.
The survey also includes the 19th century, a period of significant development in Delaware astronomy. During this time, astronomy became increasingly formalized through published works and academic instruction, including professorships in astronomy at Delaware College (now the University of Delaware). The century also saw the construction of both college-based and private observatories, the rise of gentleman astronomers, the practice of amateur telescope making (ATM), and the start of early astrophotography. The history includes the acquisition, in 1836, of a 14-foot Herschelian reflector built by Amasa Holcomb, one of America's first professional telescope makers from Southwick, Massachusetts, for use at Delaware College. Observational milestones of the period include the 1882 Transit of Venus, which saw particpation from Wilmington's gentlemen astronomers in the William Harkness Survey for the US Naval Observatory.
The survey extends into the 20th and 21st centuries, documenting both professional and amateur astronomers and the cutting edge instruments in use today, reflecting the continued advancement of astronomical knowledge and activity in Delaware.
To support this initiative, a living spreadsheet has been created and will be continuously updated as data is collected. The DAS Library is also assembling a research archive of images and documents, which will be made available to researchers upon request.
Survey submissions are encouraged. Volunteers are welcome. Help us write the history of Delaware Astronomy. Please contact:
DAS Survey of Delaware Astronomers and Telescopes
Please email