These letters are from Rutherford to Bertram Borden Boltwood, the Yale University chemist who worked with Rutherford on his scientific study of radioactivity and the structure of the atom. There is much information concerning professional activities and colleagues.

These classroom notes, taken by an unidentified student, present the state of knowledge in natural philosophy, especially astronomy, during these years. There are mentions of many contemporary scientists, and much on Newton and Newtonian philosophy.