used it as a base for entertaining friends and scientific colleagues. His maritime interests continued in 1871 when he was appointed to the Board of Enquiry into the sinking of . In June 1873, Thomson and Jenkin were on board the Hooper, bound for Lisbon with of cable when the cable developed a fault. An unscheduled 16-day stop-over in Madeira followed and Thomson became good friends with Charles R. Blandy and his three daughters. On 2 May 1874 he set sail for Madeira on the Lalla Rookh. As he approached the harbour, he signalled to the Blandy residence "Will you marry me?" and Fanny (Blandy's daughter Frances Anna Blandy) signalled back "Yes". Thomson married Fanny, 13 years his junior, on 24 June 1874. Other contributions Thomson and Tait: Treatise on Natural Philosophy Over the period 1855 to 1867, Thomson collaborated with Peter Guthrie Tait on a text book that founded the study of mechanics first on the mathematics of kinematics, the description of motion without regard to force. The text developed dynamics in various areas but with constant attention to energy as a unifying principle. A second edition appeared in 1879, expanded to two separately bound parts. The textbook set a standard for early education in mathematical physics. Atmospheric electricity Kelvin made significant contributions to atmospheric electricity for the relatively short time for which he worked on the subject, around 1859. He developed several instruments for measuring the atmospheric electric field, using some of the electrometers he had initially developed for telegraph work, which he tested at Glasgow and whilst on holiday on Arran. His measurements on Arran were sufficiently rigorous and well-calibrated that they could be used to deduce air pollution from the Glasgow area, through its effects on the atmospheric electric field. Kelvin's water dropper electrometer was used for measuring the atmospheric electric field at Kew Observatory and Eskdalemuir Observatory for many years, and one was still in use operationally at the Kakioka Observatory in Japan until early 2021. Kelvin may have unwittingly observed atmospheric electrical effects caused by the Carrington event (a significant geomagnetic storm) in early September 1859. Kelvin's vortex theory of the atom Between 1870 and 1890 the vortex atom theory, which purported that an atom was a vortex in the aether, was popular among British physicists and mathematicians. Thomson pioneered the theory, which was distinct from the seventeenth century vortex theory of Descartes in