Observations at the Magnetic and Meteorological Observatory, at the Girard College, Philadelphia: Volume 2

Observations at the Magnetic and Meteorological Observatory, at the Girard College, Philadelphia: Part 1

Observations at the Magnetic and Meteorological Observatory, at the Girard College, Philadelphia: Volume 3

Observations at the Magnetic and Meteorological Observatory, at the Girard College, Philadelphia: Part 1

Observations at the Magnetic and Meteorological Observatory, at the Girard College, Philadelphia: Part 1

Observations at the Magnetic and Meteorological Observatory, at the Girard College, Philadelphia: Part 1