October 1914: the destroyer Svea emerged from the Stockholm archipelago bearing south-south-east. On board was Lars Tobiasson-Svartman, a naval engineer charged with making depth soundings to find a navigable channel for the Swedish navy. As a child Tobiasson-Svartman was fascinated by measurement; nothing is as magical as exact knowledge. His instinct for his profession is reflected in the comfortable domesticity he enjoys with his wife - herself meticulous in every detail.