The twelfth volume of The Correspondence of John Tyndall contains 326 letters and covers the fifteen months of Tyndall’s life from March 1871 through May 1872, a time when he was a central figure in the field and had a substantial reputation in both the UK and the United States. It begins just before the publication of Fragments of Science in April and Hours of Exercise in May. It includes a number of small but public disputes about science, most notably the start of a controversy about Kew Gardens involving botanist Joseph Hooker. Tyndall was visited by friends and dignitaries; he traveled to Switzerland, Ireland, and the countryside for scrambles; and he began planning a trip to the United States. He dealt with issues concerning his family in Ireland, which were troublesome for him. He was busy administering the Royal Institution and the Royal Society; he was also working as the scientific consultant to Trinity House, which was involved in overseeing lighthouses in the United Kingdom, of which Ireland was a part at this time. Unlike other volumes, this one is not defined as much by one or two major endeavors or events for Tyndall, but instead includes a number of smaller projects as well as personal and professional issues.