The Excelsior IV Log is a nautical instrument for measuring a vessel’s speed and distance travelled. When navigating a ship it is essential to be able to estimate the boat’s speed and distance travelled to determine its position at sea. In times past the only way to measure a ship’s speed was to throw a wood log into the water and observe how fast it moved away from the ship. In the 16th century, the log was fastened to a rope knotted at set intervals. The log was thrown over the stern (back) of the vessel and a crew member counted the number of knots that were paid out in a set time. From this, they could estimate the speed of the vessel through the water. This was known as streaming the log and is also the derivation of the knot as a measurement of nautical speed. The Walker’s Excelsior Mark IV instrument was designed for smaller vessels, such as yachts, launches and fishing vessels. Historical: Thomas Walker & Son was internationally renowned in the manufacturing of ships logs, founding father , Thomas Walker (1805–1871), an engineer in Birmingham, patented a mechanical log in 1878 which was a recording instrument that attached to a rail at the stern of a vessel connected by a long cord with a rotor which was towed behind the ship. The instrument dial recorded the distance travelled. Thomas Walker first went into business to manufacture stoves at 58 Oxford Street Birmingham. Walker’s self-feeding stove was widely lauded at the Paris Exhibition of 1855, winning a prize medal and kick starting the first of many notable innovations for the Walker family's manufacturing business. However, it wasn’t until working on an earlier ship’s log model invented by his Uncle that Thomas Walker became interested in the further development of this device, used to ascertain a ship’s speed. Walker continued to improve on the common log for the company of Massey & Sons and these improvements were deemed revolutionary. This log became a firm favourite of the West India Association (British-based organisation promoting ties and trade with the British Caribbean), being the most common log in use for two generations. It took until 1861 for Thomas Walker and his son, Thomas Ferdinand Walker (1831-1921) to patent the first Walker log of many. Together, with the introduction of the A1 Harpoon Log two years later, they established the Walker Log Business as a force to be reckoned with. By the time of his passing in 1871, Thomas Walker Snr had not only founded a family business with considerable staying power but also instilled a tradition of public service. Having sat as a representative on the Birmingham Town Council for 15 years and played an active role in public works, he was soon given the nickname of ‘Blue Brick Walker’. Much like his father, Thomas Ferdinand Walker changed the face of the maritime industry. His patent of 1897, the ‘Cherub’ log, was a notable departure from the past providing a far more accurate reading and replacing the majority of logs of the age. They were the first to produce an electric log and the Walker factory was one of the first to introduce the 48 hour work week for employees. The ship log was invented and made by a significant marine instrument maker and innovator of machinery. It demonstrates the huge leap taken to improve navigational accuracy at sea with an instrument that was in use for decades.Ship's Taff Rail Log, rope attached. Walker's Excelsior IV Log model. Nautical miles dials: units and 10's. "Walker's Excelsior IV Log", "Made in England by Thomas Walker, Birmingham"flagstaff hill, warrnambool, shipwrecked-coast, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, log register, taff rail log, taffrail log, marine navigation, a1 harpoon log, cherub’ log, walker’s excelsior mark iv log, ship’s log instrument, mechanical ship’s log, measure ship’s speed, nautical instrument, navigation instrument, massey & sons, thomas walker, blue brick walker, thomas walker & son, thomas ferdinand walker, 48 hour work week