Thomas Stevenson (1818-1887) was the son of the engineer Robert Stevenson, and father of the writer Robert Louis Stevenson. Like his brothers David and Alan, he became a lighthouse designer, being responsible for over thirty examples around Scotland. Throughout his career he was interested in the theory as well as the practice of his profession, and published over sixty articles on engineering and meteorology. He was an international expert on lighthouses and harbour engineering. This work was first published in 1864 as a development of his article on harbours in the eighth edition (1857) of the Encyclopaedia Britannica, and considerably expanded in a second edition of 1874 which is reprinted here. Stevenson studied how the wind, waves and tides would act on the coastline and man-made structures, and the design of each harbour needed to take a wide range of factors into consideration.