This collection consists of three letters written to his family in England on the voyage out to New Zealand, letters written from Waimate, pages from his journal while on the Isle of Mare in the Pacific, and other related items including letters to Nihill’s father on the occasion of his death in 1855.

Nihill's letters contain numerous references to the Bishop (who evidently took a close interest in the young and promising missionary) and give vivid and detailed accounts of day-to-day life in the colony and the progress of the mission, describing the school for natives which Nihill was superintending and his relationship with various Maoris, the development of the printing press which he was running, etc.

The series contains several long journal letters, including a journal of a trip to "Taurange, the Lakes and the Waikato written for dear mama in the hope that it will give her an idea of what travelling in New Zealand is like" covering the period 21 December 1849 to 9 January 1850.

After Nihill was ordained, he was given a cure on the island of Mare in New Caledonia in the Pacific, and his first letter from there on 1 August 1852 contains an interesting account of his first impressions of the island and the work on which he was embarking. Nihill died prematurely on the island of Mare (alias Nengone) in April 1855.