If you happen to have a UK recognized civil or mechanical engineer in your family tree Ancestry's new collection of professional records prior to 1930 is a must visit. Some people included worked outside the UK.
UK, Civil Engineer Records, 1820-1930 includes 21,580 records organized by date of entry into The Insititute of Civil Engineers. The documents included support the candidates application for entry and includes name, date of birth, a summary of professional career and names of at least five corporate members of the Institute.
UK, Civil Engineer Photographs, 1829-1923 is a smaller collection, 836 entries, of very nice cabinet and carte de visite photographs. Some have additional information.
UK, Mechanical Engineer Records, 1870-1930 has74,258 records.
"This database contains registers of members, proposals for memberships and changes to membership (such as associate member to member), and related records, including the following IMechE collections:
membership records of IMechE (1847–1930)
register of members (1847–1930)
typescript membership proposal forms
membership records of IAE (1906–1930)
membership records of ILE (1915–1930)
UK, Civil Engineer Photographs, 1829-1923"