British and Irish biographies 1840-1940, published by Chadwyck-Healey, contains over 300 biographical sources, reproduced on microfiche. The collection is arranged in six parts. Chadwyck-Healey produced an alphabetical name index to parts one to three. This index, which is on microfiche on open access in the Humanities Reading Room at shelfmark HLM920.041, is the most effective way of searching the first three parts. In the case of parts four to six users need to consult the list of sources enclosed with the microfiche index at HLM920.041 to see whether any of the individual sources is likely to be relevant to their research.