The marine chronometer or sea clock was the first precise instrument used to figure out distance between two locations. The difference between the time of day anywhere on land or on the ocean and the time of day at Greenwich, England, was used to measure distance between the two places. Because the size of the Earth was already known at that time, the distances between two places could be measured. For example, if it’s 6 AM in Winnipeg, it will be noon in London, England. Therefore there’s a quarter of the day difference between the two cities. The distance between the cities is 6,300 kilometres, a quarter of the total distance of the world’s surface. All marine chronometers kept Greenwich time precisely. This was essential for finding the exact location when navigating on the Earth’s oceans. Explorer James Cook used the very first marine chronometer. He accurately charted parts of the Pacific Ocean’s coastline including the islands of New Zealand and Tahiti. By the end of the 18th century, accurate charts of the oceans, continents and islands were produced with the information obtained by naval explorers. No navigator using the marine chronometer could have an excuse for not locating a charted island or for being wrecked on a charted coastline. This special clock was constructed in such a way that it could operate upside down or while it was moving around. All other clocks of that time had to operate on a flat, level surface. A coiled spring replaced the pendulum; it allowed this clock to function even in the worst storms at sea. Built from brass parts, it required no oil and was resistant to temperature and humidity changes. This clock kept time so well, it only lost a few seconds in a month. The marine chronometer was one of the most ingenious inventions of its time! In the Museum’s Hudson’s Bay Company Gallery, there is a marine chronometer that looks like an ordinary oversized pocket watch. Sir John Franklin, a well-known naval explorer, used this marine chronometer on his second Arctic expedition in 1825. He was searching for a safe route between the Atlantic and Pacific Oceans by travelling through the Arctic waters of North America. Franklin and his crew went missing from their third Arctic expedition in 1848. Ironically, a search party looking for Franklin in 1853 used this same marine chronometer. With the marine chronometer, many long distance trade routes were charted.

Finding shorter routes to reach the Orient by sea was a priority. Perfumes, spices, tea and silk were in great demand in Europe. That’s why Sir John Franklin was assigned by the King of England to find a quick and safe route through the Arctic waters of North
America. It was discovered later that everyone in Franklin’s third Arctic expedition died. The British Admiralty thought Franklin’s
marine chronometer broke during the mission and caused the crew to lose their way in the Arctic. By 1850, all British naval ships were issued three marine chronometers to make sure the crew had the
correct time, should one clock stop working properly. Eventually radio receivers providing Greenwich time replaced the marine chronometer. Today, all vessels use a Global Positioning System or
GPS. This pocket-sized instrument uses satellites orbiting the Earth to determine the exact location of the user to the nearest square metre. Today, most people rely on clocks and wristwatches to tell
time, to plan days and organize trips. The development of accurate timepieces was the result of the invention of the marine chronometer. Imagine a world without them!

- Jérôme Marchildon, Interpreter -