During the 19th century, the British Empire covered about 10,000,000 square miles populated by 400 million people. The only real superpower of the Victorian era, England's reach was due to its domination of the sea. How did they do it? Through innovations in timekeeping.

In the late 15th century, when Christopher Columbus was exploring the globe, primitive sand or sandglass clocks were used to mark time in half-hour increments. Since the watches lasted four hours, the helmsman would mark the end of the first half-hour with one bell, the end of the second with two bells, etc., until he hit eight bells at the end of his watch. Time would be tracked as such: One bell for 4:30, 8:30, and 12:30; two bells for 5:00, 9:00, 1:00; three bells for 5:30, 9:30, 1:30; four bells for 6:00, 10:00, and 2:00; five bells for 6:30, 10:30, and 2:30; six bells for 7:00, 11:00, and 3:00; seven bells for 7:30, 11:30, and 3:30; and eight bells for 8:00, 12:00, and 4:00.

Despite this clever manual timekeeping method, before the mid-1750s, one of the most difficult problems seafarers faced was how to calculate their ship’s position on the globe when there was no land in sight. Using “celestial navigation,” one could figure out latitude measuring the sun’s angle at its highest point in the sky at noon. But to measure longitude accurately based on the sun’s position, you needed to know exactly what time it was at a fixed location, usually the Greenwich Meridian. Then, the longitudinal distance could be calculated comparing the time with that of the fixed location.

At the time, the most accurate, reliable timekeepers were regulator or pendulum clocks, but these proved useless at sea because they got thrown off-balance by the rolling waves and the 0.2 percent variation in gravity around the globe. In 1675, the inventor of the pendulum clock, Christiaan Huygens, came up with a portable clock that used a balance wheel and a spring for regulation, but it was still not accurate enough to use for navigation. This invention, however, paved the way for pocket watches and wristwatches.

The British government was so determined to find the solution to this problem that in 1714, it offered a prize of 20,000 pounds (the equivalent of millions of dollars today) to an inventor who could come up with such seaworthy devices, dubbed “marine chronometers” by inventor Jeremy Thacker. A carpenter from Yorkshire, John Harrison, then made it his life’s mission to come up with such a clock.

Harrison’s first marine chronometers, H1 and H2, completed in 1735 and 1741 respectively, each used a pair of counter-oscillating weighted beams, which were connected by springs. While these were not affected by the ship’s motion, they were sensitive to centrifugal force, making them too imprecise for navigation. His H3, attempted in 1759, introduced circular balances, a bimetallic strip, and caged roller bearings—inventions that are still used today.

But Harrison wasn’t able to claim the 20,000-pound prize until 1761, when he ditched the circular balances for a fast-beating balance wheel that had a balance spring with a bimet...

Then, in 1766 in France, Pierre Le Roy created a marine chronometer using his major clockwork innovation, the detent escapement, with a temperature-compensated balance and a hairspring. Both France’s Ferdinand Berthoud and Thomas Mudge came up with their own marine chronometers, but the device wasn’t perfected until 1780, when Brits Thomas Earnshaw and John Arnold patented a streamlined chronometer with a detached spring detent escapement. These are the most precise portable mechanical clocks ever made, losing around 0.1 second per day, and allowing navigators to determine their ship's position within 4,600 feet after sailing for a full month. Earnshaw and Arnold, fierce competitors, each made about 1,000 chronometers.

At first, these new marine chronometers were so costly few ships’ captains could afford them. Part of the reason chronometers were so expensive is that they often used hard gemstones like ruby or sapphire for the ball bearings to diminish the wear on the escapement. They were also enclosed in a brass case head in gimbals in a mahogany box so that the chronometer stayed level even as the ship swayed.

But for the British Royal Navy, outfitting its fleet with chronometers became a priority by 1825, giving the United Kingdom a navigational advantage on the high seas. The Navy ships preparing for a long journey would dock on the River Thames at Greenwich, and wait for a time ball on a tower to drop at exactly 1 p.m., to set their chronometers. That’s how Greenwich Merdian became the international starting point for measuring time zones.

In the United States, coiled springs were not easy to come by, so most clockmakers built weight-driven clocks until the early 19th century. In the mid-1820s, a few hundred of spring-driven clocks, made with imported springs, were produced by Curtiss & Clark in Plymouth, Connecticut, but they did not sell as well as the cheap wooden clocks available at the time.

But it wasn’t long before the concept of portable clocks, particularly those using oscillating balance-wheel clocks that would operate while moving on uneven surfaces or in different positions, caught on. The earliest balance-wheel clocks in the U.S., were called “marine clocks,” to boast about their potential use at sea, regardless whether they were employed on actual ships.

Famous clockmaker Eli Terry received a patent in 1845 that inspired his son Terry to develop a variety of these marine clocks for mass production, but they were not a hit with the public until 1847. That same year Charles Kirk of Bristol, Connecticut, received a patent for a portable clock with a two-pallet escapement. Around 1890, the marine-clock movement evolved into the same movement that would be used almost universally in mechanical alarm clocks in the 20th century.

Prior to 1900, though, the U.S. Navy was still using the 8-chime ship’s bell code from the days of Columbus. Sailors on watch often relied on their pocket watches and then struck the bells themselves. In the late 1800s, clockmakers set about trying to make clocks that could strike bells in certain increments without disrupting the operation of the time movement. In particular, clocks that could mark the standard mariner’s watches were known as “ship’s bells clocks.”

Seth Thomas Clock Company produced an early ship’s bell clock, which resembled a kitchen clock in a tin can or wood case; meanwhile, Tiffany Makers of New York crafted a limited number of high-quality ship’s bell clocks, but these were only available to members of the elite New York Yacht Club.

At Boston Clock Company, formerly the Harvard Clock Company, John S. Negus and Joseph Eastman started developing their tandem wind movement in the late 1880s, and this invention was patented in 1893, a year before Boston went out of business. Eastman took this concept and formed the Vermont Clock Company with George D. McMillen, which got into an intense competition with Walter K. Menns and the Cheslea Clock Company between 1897 and 1900 to mass-produce the top-quality striking ship’s bell clocks.

An important but rare Boston model called the Locomotive seems to have inspired Chelsea Clock Company when it introduced its line of “marine” clocks in 1897. A year later, Chelsea patented a movement by George W. Adams, which the firm called 4L. This patent, modified by Menns for ship’s bell clocks and assigned to Chelsea owner Charles L. Pearson, was the foundation of Chelsea’s iconic ship’s bell movement, which turned out to be more reliable than the Vermont clocks and earned the Chelsea clocks the nickname, “Timekeepers of the Sea.” Chelsea ship’s bell clocks are still produced today, with brass workings and a patented mahogany case.

Real marine chronometers were also handcrafted continually into the 1970s, by companies such as Mercer of St. Albans. Swiss watch companies Ulysse Nardin attempted to create interchangeable parts for chronometers at the turn of the 20th century, but it wasn’t until the beginning of World War II that Hamilton Watch Company began to mass-manufacture high-quality chronometers for the U.S. Navy and other Allied ships.

Ships today use the satellite-based Global Positioning System for navigation, but international mariner certifications for deck officers like Master, Chief Mate, and Officer in Charge of Navigational Watch require the ability to apply celestial navigation using modern marine chronometers, which are quartz clocks corrected regularly by GPS or radio time signals.

About our sources | Got something to add?

▼ Expand to read the full article ▼

Best of the Web (“Hall of Fame”)

National Watch and Clock Museum

National Watch and Clock Museum

This virtual museum, created by the National Association of Watch and Clock Collectors, lets you stroll through tim… [read review or visit site]



Bill Stoddard's clock history site offers a trove of great reference information on clock and watch makers includin… [read review or visit site]

National Maritime Museum

National Maritime Museum

Check out this sampling of nautical and maritime items held by the U.K.'s National Maritime Museum and Royal Observ… [read review or visit site]

Dan and Diana's Lux Clock Collection

Dan and Diana's Lux Clock Collection

Dan and Diana Lockett's amazing collection of several hundred novelty Lux clocks made by the Lux Clock Manufacturin… [read review or visit site]

Detex Watchman's Clock Album

Detex Watchman's Clock Album

Philip Haselton's guide to watchmen's time recording equipment. Includes 19th century German portables, 20th centur… [read review or visit site]

Clubs & Associations

Discussion Forums

Other Great Reference Sites

Most watched eBay auctions    

Vintage 1960s Chelsea Ships Bell Brass Clock, Thermometer & Barometer, Nr1890 Seth Thomas Exposed Ships Bell Striker Ship ClockHuge Maritime Ships Mercer Bulkhead Clock Brass Case English Nautical ShippingChelsea Ship's House Bell Clock 8 Inch Special Grand Dial Jaccard And CoChelsea Solid Brass Ship Clock With Subsidiary Seconds HandChelsea Clock Co U.s. Revenue Cutter Service Ships Clock Dial Super Rare PartsVintage Chelsea Ship's Clock Movement Early Boston Clock Co Ship's Clock, Dated June 1916, Nickel Plated Case- Rf25488Rare Seth Thomas U.s.l.h. Service Ship's Clock Dial & Movement Lighthouse Chelsea Ships Clock By Abercrombie & Fitch MetalVintage Schatz Ships Bell Clock Working Stunning Thomas Mercer Ltd Marine Chronometer Ship Clock W/ Original Wood BoxesVintage Seth Thomas Mayflower 3 Brass Ships Bell Clock With KeyVintage Chelsea Clock Co Boston Us Navy Boat Ships Clock Parts RepairSeth Thomas Corsair Ships Bell Key Wind Brass Clock Model 1004 Nice Cond!Seth Thomas Brass Key Wind Ships Clock, For Parts Or RestorationAssortment Of 25 Ship Deck Clock Second Hands, Used, Chelsea?, Seth Thomas?Vintage Chelsea Ships Clock With Key - Baker Lyman Co - Lykes Lines 1955 - 1959Seth Thomas Us Coast Guard Ship's Clock Dial 6"Antique Weatherstation Ships Wall Clock, Barometer, Thermometer Mahogany CaseGreat Working Vintage Smiths Empire Brass Cased Ships Wheel Alarm ClockThe Captains Empire Bulkhead Ships Clock From The Mv "thomas Hardie"Chelsea Ships Clock U.s.navy Mark 1 Deck Clock 1938 As Found Needs Work And BackVintage Schatz German Made, Royal Mariner Clock, Ships BellVintage Seth Thomas Helmsman Base E537-005 Ships Wheel Shelf Mantel Clock Germa Seth Thomas Brass Ship ClockAntique Seth Thomas Brass Ship Clock With Wind Up KeyVintage Seth Thomas Ship's Clock Movement With Plate For 4 1/2" DialSmiths Brass Ships ClockOld Stock Hermle Platform Escapement Clock Part For #132-071 Ships Bell MovementChelsea Bicentennial 76 Limited Edition Ship Bell Mantle Clock 1776/1976 W/ KeyVintage Schatz Brass Ship Clock Made In GermanyIncomplete Chelsea Ship's Clock Movement Lot C Assorted 24 Pc Lot Of Ship Deck Clock Mostly Minute Hands, Seth Thomas? Chelsea?Schatz 6" Brass 8 Day Ship Wheel Bell ClockVintage Polished Chrome Chelsea Collectible Desktop Nautical Compass Table ClockNautical Mermaid & Conch Shell Blue Ocean Beach Home Wall Clock Decor - NewMarine Chelsea Clock Co. Brass Screw Ship’s Barometer Nautical 7 ¼” VintageVintage M Low Us Army Message Center M2 Ship's Clock Dial Fits ChelseaRare Fulton Clock Company Ship's Bell Clock Movement Dial Plate PartsVintage Kit Kat Klock, Cali Clock Company, Beige, Ships FreeM Low Radio Room Ships Clock Dial For Chelsea Movement?Vintage United Ship Boat Mantel Clock Model-811 ...lookAssortment Of 10 Ship Deck Clock Second Hands, Nos, Unknown MakerSwift Marine Ships Clock Striking Made West Germany For Swift Co. Boston Mass. Chelsea Ships Clock Abercrombie & Fitch Brass Patina WorkingVintage Unsigned Ship's Clock Chronometer Movement Parts Project Vintage Seth Thomas Corsair Model E537-000 Mantle / Ships Clock Antique Ansonia Spelter Barge Novelty Clock Cupid W Torch On Ship W/shell Tlc Seth Thomas Ships Clock Case WwiiSeth Thomas Ship's Clock Movement No. 10jLot Of (44) Takane Clock Movements No 0 Jewels Some Pointers Also.free ShipAntique Gilbert Banjo 1807 Clock With Sailing Ship- For Parts Or Repair French Chrome Ships Clock Spares Or RepairAntique New Haven Banjo Wall Clock Sea Foam Green Warwick Sea Nautical Wooden Brass 18" Ship Wheel Pirate Captain Antique Clock Maritime Vintage Sepo41United Vintage Wood Ship Clock With Night Lights & Metal Sails Model 811 Vintage Urgos Ships Clock. Works Great.Salem Ships Bell Clock 8 Day Chrome Finish Wheel Nautical Vintage Maritime Ship's Solid Brass Gimbals Ships Clock