4 pages (five with overwriting on page 3). Edward Pickering had just graduate from Harvard and became a Professor at the Massachusetts Institute of Technology. He later made the Harvard College Observatory known and became a leading writer on astronomy and after questioning Niels Bohr on atomic structure, he became convinced of Bohr's theories. He is writing to his friend Conwell who was classmate from the Lawrence Scientific School. He writes of his collection of photographs of bridges, he notes he has over 100 stereoscopic views from Europe (courtesy of Anthon in New York), He notes a Professor E. is interested in the project. He inquires about the bridge at St. Paul over the Mississippi as well as the Railroad Bridge, notes the one destroyed by weather, notes the Bangor Bridge in Maine with nice description, says class he is teaching has twenty promising young men, a very nice letter. Later this fascination with photography led to his method to photograph the spectra of multiple stars by putting a large prism in front of the photographic plate. A bit of staining to last letter.