This research is part of a long-term editing project, the first comprehensive edition, in three volumes, of James Clerk Maxwell's scientific letters and manuscript papers, to be published by Cambridge University Press. Maxwell was the most important physicist of the nineteenth century, and his work was seminal in establishing the electromagnetic theory of light and statistical physics, work that is fundamental to modern science and technology. Under this grant, Dr. Harman is working on the editorial commentary for Volume II of the edition, which covers the years 1862-73. The manuscript papers of this period, which are of especial interest and complexity, shed important light on Maxwell's scientific maturity, the period in which he wrote the classic works on field physics and statistical molecular theory on which his unique reputation largely rests. The edition aims at textual accuracy and completeness. The textual notes and introductions clarify textual obscurities and establish the historical context within which the documents were written, employing contemporary published and manuscript sources. The work, to be carried out at Harvard University in consultation with historians of physics in the Boston area, will make available, in a critical edition, fundamental source materials for the study of modern science.