Field Trip: Nautical Instruments

Value (2016) | $3,000 Auction$1,000,000 Auction
Watch  

HOST: Sailing is a popular activity in Corpus Christi Bay. Global positioning system devices help sailors find their way today. But what did mariners from long ago rely on to navigate the seas? Appraiser John Snellenburg was on deck to explain.

APPRAISER:
An astrolabe allows you to determine your latitude. Very simply, it tells you how far north or south you are on the ocean. HOST: Can you show me how it works?

APPRAISER:
I couldn't show you with this one, but I'll show you with a reproduction that we have here. It's a very simple device, circular with a degree scale around it. We then use the sighting vane to determine how high the sun is at its highest point. We then are able to-- using a set of tables that were derived in the 15th century-- tell what our latitude is. HOST: So John, where is this astrolabe from?

APPRAISER:
This was from a shipwreck from 1554 off Padre Island. It's an astrolabe that was made in 1545. HOST: Well, it's one of the many treasures that are now in the Corpus Christi Museum of Science and History. Mariners' astrolabes are incredibly rare things because they were quickly supplanted by other navigational devices. And virtually all the ones that we have that survive today were taken from shipwrecks. While this is the property of the museum here, if we found a comparable astrolabe that had survived all those years, what would be the value?

APPRAISER:
Well, it depends. Most of these are relics. The most recent mariners' astrolabe that had sold was property of the Time Museum and sold about eight or nine years ago. But it was a completely crusted over, illegible piece and it sold for about $3,000. However, about 25 years ago, astrolabes in good condition, which were sold from the shipwreck of the Atocha-- a famous Spanish treasure ship-- made comfortably into the mid five figures, $40,000, $50,000. HOST: So we know with the astrolabe from the 1500s we could measure latitude, but what about longitude?

APPRAISER:
Longitude was a much more difficult problem. It requires a timepiece that was accurate within two seconds over a voyage that could have lasted months and even years. In 1707, the English fleet was wrecked off the coast of Cornwall with a loss of pretty much all hands. It was such a naval disaster that the English Parliament passed what was known as the Longitude Act. They offered a reward of £20,000 at a time when a middle-class wage was a mere £100. So in fact, they were offering 200 years' wages for a way to determine the longitude. This chronometer was sold by Negus of New York, about 1875. And for all intents and purposes, it's virtually identical to the chronometers that were invented in the 18th century. Chronometers such as this appear frequently at auction. You can expect to pay between $2,000 and $3,000. A more important chronometer that was actually experimental might sell for $20,000 to $25,000. And indeed, a number of years ago, one of the chronometers submitted to the longitude prize made over $1 million at auction. HOST: Well, John, I certainly understand the value to collectors, but if you were at sea, the value of a working chronometer would be priceless.

APPRAISER:
It would be priceless and your life would depend on it. HOST: John, thanks so much.

APPRAISER:
You're quite welcome.

Appraisal Details

Appraiser
Bonhams, NY
New York, NY
Appraised value (2016)
$3,000 Auction$1,000,000 Auction
Event
Corpus Christi, TX (August 04, 2012)
Material
Glass , Metal

Executive producer Marsha Bemko shares her tips for getting the most out of ANTIQUES ROADSHOW.

Value can change: The value of an item is dependent upon many things, including the condition of the object itself, trends in the market for that kind of object, and the location where the item will be sold. These are just some of the reasons why the answer to the question "What's it worth?" is so often "It depends."

Note the date: Take note of the date the appraisal was recorded. This information appears in the upper left corner of the page, with the label "Appraised On." Values change over time according to market forces, so the current value of the item could be higher, lower, or the same as when our expert first appraised it.

Context is key: Listen carefully. Most of our experts will give appraisal values in context. For example, you'll often hear them say what an item is worth "at auction," or "retail," or "for insurance purposes" (replacement value). Retail prices are different from wholesale prices. Often an auctioneer will talk about what she knows best: the auction market. A shop owner will usually talk about what he knows best: the retail price he'd place on the object in his shop. And though there are no hard and fast rules, an object's auction price can often be half its retail value; yet for other objects, an auction price could be higher than retail. As a rule, however, retail and insurance/replacement values are about the same.

Verbal approximations: The values given by the experts on ANTIQUES ROADSHOW are considered "verbal approximations of value." Technically, an "appraisal" is a legal document, generally for insurance purposes, written by a qualified expert and paid for by the owner of the item. An appraisal usually involves an extensive amount of research to establish authenticity, provenance, composition, method of construction, and other important attributes of a particular object.

Opinion of value: As with all appraisals, the verbal approximations of value given at ROADSHOW events are our experts' opinions formed from their knowledge of antiques and collectibles, market trends, and other factors. Although our valuations are based on research and experience, opinions can, and sometimes do, vary among experts.

Appraiser affiliations: Finally, the affiliation of the appraiser may have changed since the appraisal was recorded. To see current contact information for an appraiser in the ROADSHOW Archive, click on the link below the appraiser's picture. Our Appraiser Index also contains a complete list of active ROADSHOW appraisers and their contact details and biographies.