Correspondence, writings, records of astronomical expeditions, diaries, notebooks and scrapbooks of David Peck Todd, astronomer and teacher at Amherst College from 1881 to 1917. Between 1882 and 1914 Todd conducted nine expeditions to various parts of the world to study solar eclipses. The notes, photographs, drawings and memorabilia of these expeditions make up a significant portion of the papers. He was also a fertile inventor, and plans and drawings for many devices, some related to solving technical problems encountered on his expeditions are included in the papers.

As an early enthusiast of aviation, he made a balloon ascent in 1910 and advocated aerial photography for recording eclipses. In Amherst he raised funds to build a new observatory in 1905 and records of this project and of his teaching career at Amherst are very well documented.

His writings include three textbooks on astronomy and a wide range of scientific and popular articles, copies of which are in the papers. His wife, Mabel Loomis Toddd, who was the first to transcribe and publish Emily Dickinson's poems, was an active social force in Amherst and their family correspondence offers a vivid picture of the life of the town as well as a remarkably frank picture of their personal relationship. She also lectured extensively, basing her talks on observations made during the eclipse expeditions.

Her letters to her husband during her lecture tours provide an insight both into her character and into female social life of the period. The 368 letters that she wrote between 1878 and 1922 are in themselves a significant section of the papers. Todd's correspondents include astronomers and scientists from all over the world as well as public figures in the United States. In 1922 he was declared incompetent and spent his remaining years in institutions.