c. 1850 - appointed principal associate in the engineering business of Professor James Thomson in Belfast

1854 - employed on railway works by Liddell and Cordon, Civil Engineers of Westminster.

18?? - resident engineer at Madras to the Great Southern of India Railway

1864 - elected member of Institution of Civil Engineers; located at 20 Duke Street, Westminster, London S W, and Goldwell House, Newbury, Berks

1868 - Professor of Engineering at University College, London.

1873-1884 - Professor of Engineering at Queen's College, University in Belfast, Ireland

1878 - patented the highly accurate cylindrical spiral slide rule

1884 - resumed work in London