About the time of the separation, he began a relationship with a married woman, Anne Maria Darley Boursiquot, the wife of a Dublin wine merchant of Huguenot ancestry.

Whilst in Dublin, Lardner began to write and lecture on scientific and mathematical matters, and to contribute articles for publication by the Irish Academy.

[2] In 1828, Lardner was elected professor of natural philosophy and astronomy at University College, London, a position he held until he resigned his professorship in 1831.

[citation needed] Lardner showed himself to be a successful populariser of science, giving talks on contemporary topics such as Babbage's Difference Engine (1834).

[3] He was the author of numerous mathematical and physical treatises on such subjects as algebraic geometry (1823), the differential and integral calculus (1825), and the steam engine (1828).

The scandal caused by his affair with a married woman effectively ended his career in England, so Lardner and his wife remained in Paris until shortly before his death in 1859.

[4] Lardner became involved in a number of ill-advised public disagreements with Isambard Kingdom Brunel regarding technical matters, in which he came off the worse.

[citation needed] During the 1833 Parliamentary hearings discussing the proposal of the Great Western Railway, Lardner criticised Brunel's design of the Box Tunnel.

[5][6] In 1838 while Brunel was building the broad-gauge Great Western Railway, Lardner carried out some experiments with the company's flagship locomotive, North Star.

Whilst lecturing in America Lardner was paid by Norris Brothers, the largest firm of locomotive builders, to investigate a fatal accident in Reading, near Philadelphia, where a boiler had exploded on a newly made train.

The Coroner's inquest jury were persuaded by Lardner that the accident was an 'act of God' but the company were careful to design their later locomotives with wrought-iron bands.