Sea ('Steam Communication with India by the Red Sea advocated in a Letter to the Right Hon. Viscount Melbourne,' London, 1837, 8vo). He also discussed, in the ‘Edinburgh Review’ for April of this year, the feasibility of constructing steamships capable of making the voyage across the Atlantic. In the course of this article, the tone of which was cautious to the verge of scepticism, he made some disparaging comments on Hall's recently patented method of condensation, which, by enabling the same water to be used throughout the voyage, effected a great economy of force. He was accordingly denounced before the British Association by the inventor as 'an ignorant and impudent empiric' (Samuel Hall's Address to the British Association, explanatory of the Injustice done to his Improvements on Steam Engines by Dr. Lardner, Liverpool, 1837, 4to). A paper by Lardner on the resistance to railway trains, read before the British Association at this meeting, was published in the 'Railway Magazine' for November of the same year, and among the 'Reports' of the association for 1838 and 1841 are two by him on the same subject, afterwards reprinted in 'Reports on the Determination of the Mean Value of Railway Constants,' London, 1842, 8vo.
In the midst of these various and arduous labours Lardner carried on during several years an amour with Mrs. Heaviside, the wife of Captain Richard Heaviside, a cavalry officer, and eloped with her in March 1840. Heaviside obtained a verdict against him in an action of seduction, with 8,000l. damages. An act of parliament dissolving the marriage followed in 1845. The interval was spent by Lardner in a lecturing tour in the United States and Cuba, by which he is said to have made 40,000l., besides the profits arising from the sale of his lectures, which were published at New York in 1842 and subsequent years, and passed through many editions. Returning to Europe in 1845, he settled at Paris, where he thenceforth resided until his death. He visited London in 1851, and reviewed the Exhibition in a series of letters to the 'Times' newspaper, reprinted under the title 'The Great Exhibition and London in 1851,' London, 1852, 8vo. Lardner also communicated in 1852 to the Royal Astronomical Society papers 'On the Uranography of Saturn,' 'On the Classification of Comets, and the Distribution of their Orbits in Space,' and 'On Certain Results of Laplace's Formulæ' (see Monthly Notices of the Royal Astronomical Society, xiii. 160, 188, 252). During his residence in Paris he wrote the works on railway economy and natural philosophy mentioned below, and launched upon the world in 1853 a miscellany of treatises on various branches of science, especially in their relation to common life, entitled 'The Museum of Science and Art,' completed in 12 vols., London, 1856, 8vo. Portions of this work were acknowledged and reprinted as Lardner's own under the titles: 'The Electric Telegraph Popularised,' London, 1855, 8vo; new edition, revised and rewritten by E. B. Bright, 1867, 8vo (German translation by C. Hartmann in 'Neuer Schauplatz der Künste,' Ilmenau, 1856, 8vo); 'Common Things Explained,' in two series, London, 1855 and 1856, 8vo (reprinted 1873, 8vo); 'Popular Astronomy,' in two series, London, 1855 and 1857, 8vo (reprinted 1873, 8vo); 'Popular Physics,' London, 1856, 8vo (reprinted 1873, 8vo); 'The Bee and White Ants: their Manners and Habits, with Illustrations of Animal Instinct and Intelligence,' London, 1856, 8vo; 'Popular Geology,' London, 1856, 8vo (reprinted 1873, 8vo); 'The Microscope,' London, 1856, 8vo; 'Steam and its Uses,' London, 1856, 8vo (reprinted 1873, 8vo).
Lardner was a fellow of the Royal Societies of London and Edinburgh, of the Royal Astronomical Society, of the Linnean Society, of the Zoological Society; an honorary fellow of the Cambridge Philosophical Society and of the Statistical Society of Paris; a member of the Royal Irish Academy, and a fellow of the Society for Promoting Useful Arts in Scotland. He was reputed to be the Paris correspondent of the 'Daily News.' He died at Naples on 29 April 1859. He is satirised by Thackeray in the last 'Memoirs of Mr. Charles J. Yellowplush,' as a literary quack advertising his cyclopædia at dinner-parties, and also as Dionysius Diddler in the 'Miscellanies.' He was certainly not an original or profound thinker, but he was a man of great and versatile ability, master of a lucid style, and as a populariser of science did excellent work.
Lardner married twice: first, in 1815, Cecilia Flood (d. 1862), granddaughter of the Right Hon. Henry Flood [q.v.], by whom he had three children. The parties separated by mutual consent in 1820, and in 1849 a formal divorce took place. The doctor then married Mary, the divorced wife of Captain Heaviside, by whom he had two daughters. A humorous sketch of Lardner, which is vouched for by the editor as a graphic likeness, is given in the 'Maclise Portrait Gallery,' ed. Bates, p. 122.
Lardner's principal works, exclusive of those of which the full titles are given in the text, are as follows: 1. 'System of Algebraic Geometry,' London, 1823, 8vo, one