By the deep, by the mark
Somerset House, Terrace Galleries
Jan 2018
By the deep, by the mark is a historic naval term for measuring the relative depths of the seabed: a process traditionally done with a plumb line by hand. This line literally connected the line- thrower with the water. Nowadays, data historically obtained "by the deep, by the mark" is integrated into complex, high-tech algebraic and simulation models.