An Introduction to Marine Timekeepers

This article could also be named “An introduction to transportation clocks,” because these types of clocks were used by navigators, meaning travelers, explorers and mapmakers to identify their locations by using the correct time and location of the heavenly bodies to pinpoint their whereabouts. However, mariners were noted in history to be the most prolific users of these timekeepers.

Clepsammia, widely known today as the sandglass or hourglass.

Clepsammia, widely known today as the sandglass or hourglass.

The first nautical timekeepers used were clepsammia, widely known today as the sandglass or hourglass. Ships used hourglasses of three basic time durations, four hours, thirty minutes and 28 seconds. The 28-second hourglass was used for measuring the ships speed in knots. When measuring the ship’s velocity through the water, a hemp rope with knots tied in certain intervals was thrown overboard and after 28 seconds the number of knots that could be seen on top of the water was counted; hence the term “speed in knots” came about. The other intervals will be discussed later in this article.

With the discovery of the new world, ships’ navigators needed more precise timekeepers to better navigate the vast oceans. After the loss of four battleships at sea due to the crude methods of navigation in use at the time, the British parliament in 1714 declared a 20,000-pound sterling prize (that’s more than $10,000,000 in today’s money) to anyone who could come up with an accurate navigational method. James Harrison was finally awarded the prize in 1773 for his life’s work and after a huge political battle. The story is well-told in the bestselling book “Longitude” by Dava Sobel, published by Penguin books in 1996.

Harrison's marine chronometer, whicfh earned a 20,000-pound sterling prize ni 1773

A fusee mechanism from an English ship's clock.

Harrison’s work bought about the invention of the marine chronometer, a term that is now reserved for only the most accurate of portable timekeepers. Many improvements were made upon the original, and by the second half of the nineteenth century, just about every large seagoing vessel had at least one chronometer on board. There are collectors today that search for chronometers exclusively and seek the early rare ones, as well as ones that need to be wound only once a week or have unusual or innovative mechanisms. This is not to say other chronometers are not collectible; even those made for the many of the world’s navies before the advent of quartz timekeeping technology (1960’s) still command high prices.

The old ship’s bell clocks found on today’s market also have a large collector’s following and come in many styles and sizes. The term “ship’s bell clock” refers to a clock that strikes ship’s watch hours used by seafarers worldwide. Western mariners used four-hour intervals divided into half hour segments. The Turkish Navy used a five-hour watch cycle, but I’ve never seen a clock made with that bell ringing scenario.

A marine chronometer by D. McGregor & Co.

A marine chronometer by D. McGregor & Co.

The ships bell clock rings like so: 12:30, one ring; 1:00, two rings; 1:30, three rings… and so on… until 4:00, then eight rings.

The cycle begins all over again and has six cycles during a 24-hour period. The sandglasses were used for the same function in years earlier, but the automated ringing of the bells, as you can understand, is not subject to as much human error. After eight bells rang onboard a vessel, seamen would shift to different duties to keep from succumbing from the monotonous boredom inherent to their seagoing life, like watching out for pirates, reefs and, of course, mermaids!

Today’s market has made ship’s clocks very popular as collectors the world over seek out examples of our nautical history. Most ship’s clocks produced around the world were made of heavy brass or bronze that could withstand the extreme conditions of the unpredictable sea. Because of this, many still exist on the market, and I’ve even heard tales of ship’s clocks being salvaged from wrecks and restored to working condition. Many makers produced ships clocks over the last 100 years or so, and some of the most collectible are ones with fusee mechanisms, (a fusee is basically a cone shaped arbor with a gear that acts as a mini transmission to keep a constant torque on the mechanism as the spring winds down and loses power). Also, models with outside attached bells and clocks marked with the particular ships’ names that carried the clock are highly desired colletors’ pieces.

A clock labled U.S. Navy with a fusee mechanism

A U.S. Navy ship's clock made by the Chelsea Clock Co., Boston.

The most prolific maker of ship’s clocks in the U.S. is Chelsea Clock Company of Boston (1899-present), and the most advanced collectors seek those examples with early serial numbers (under 25,000) and with 8-inch dials and larger. Also, some of Chelsea’s predecessor companies are quite in demand; such as the Harvard, Vermont and Boston Clock Companies. For a great explanation of how these and other Chelsea clocks fit into the collector’s scheme of things, you should visit Jim Dyson’s Chelsea Clock museum. I have a soft spot for transportation clocks, as well as hourglasses, too, so look for follow up articles on this subject from me in the future.

Mark Peer is a Worthologist who specializes in clocks.

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