William Thomson, later Lord Kelvin, was born in 1824 and died in 1907. During his lifetime, Thomson published more than 600 scientific papers on various subjects ranging from navigation at sea to the laws of thermodynamics. He was also a brilliant inventor, capable of finding practical solutions to highly complicated problems.
William Thomson's most famous invention was the Kelvin temperature scale. Unlike the Celsius and Fahrenheit scales, both of which are used in daily life, the Kelvin scale is more often used by scientists today. The zero point on the Kelvin scale is equal to -273.15 degrees on the Celsius scale. "This zero point is considered the lowest possible temperature of anything in the universe," says the Windows to the Universe website. The scale measures "absolute temperature," a more valuable and precise temperature measurement for scientists than that provided by the Celsius and Fahrenheit scales.
Thomson worked with the Atlantic Telegraph Company in the mid-1800s. The Atlantic Cable Expedition of 1857 was an attempt to lay a telegraph cable across the Atlantic Ocean. The expedition was initially unsuccessful but Thomson's mirror galvanometer helped to get the project back on track. According to the National Library of Scotland website, the invention was designed to measure electric current flowing through the newly laid cables, a vital indicator of successful installation. The project was completed in 1866, and the first transatlantic telegraph cable had been laid.
In the 1870s, Thomson set about improving the existing mariner's compass, an item in which he saw a number of faults. He mounted a shorter needle on a lighter card and used a shield to protect the compass from the magnetism of a ship's hull. His improved compass was an instant success and, according to the Today in Science History website, "was used almost universally until the advent of the gyrocompass."
Thomson invented an improved system for measuring the depth of water below a ship. Existing sounding equipment was very basic and time consuming. A weighted rope was lowered to the ocean floor before being hauled back up and measured. Thomson's system used piano wire, which could be raised and lowered mechanically, to lower a small glass tube into the water. The glass tube contained a chemical-based system for recording the depth of water, and the measurements taken could be quickly read once the tube had been brought back to the surface.
Thomson carried out a number of mathematical investigations into the nature of waves. These led to a succession of inventions designed to measure tidal movements. He invented and developed "a series of tidal meters, analyzers and predictors which allowed the prediction of the tide in any port in the world," according to the University of Glasgow Special Collections website.
Thomson used his knowledge of physics, astronomy and navigation to develop his own astronomical clock. While not strictly a new invention, his newly patented clock was "as accurate as any in existence at the time," according to the National Library of Scotland website.