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Long Live the Sextant
You also can’t beat this technology for its staying power. The basic
design of the sextant has not changed since the 18th century, and they
were still being used up until about 30 years ago when GPS became
the new normal. At their best, a sextant can place you within a mile
and a half of your actual location, which explains why their use got
much more infrequent in the wake of something that could place you
with only a foot or so of error. They are not yet obsolete, however. The
US Navy still trains sailors in celestial navigation and sextant use as a
backup should GPS (or electricity, in some cases) fail. The sextant has
the added bonus that it’s not vulnerable to hacking, which is becoming
an increasing concern.

What do you do when it’s so foggy you can’t see the horizon? Some turned
to artificial mercury horizons to use their sextants. Mercury was
poured into a container and covered with a triangular “tent” to
keep the wind from disturbing the surface. The benefit of mercury
was that it was reflective and would still allow you to see the
celestial body when in use. A sailor would measure the vertical
Thanks to the foresight of their planetarium’s director Don Treworgy, angle of the celestial body against its reflection in the mercury
Mystic Seaport Museum in Connecticut has an impressive Photo: The Museums Victoria Collections
84 sextants in their collection, along with several other
fascinating nautical items. Stop in for a visit!
Photo: “Roadschooling Shermans”
Variants on This Theme
A Piece of Technology to Collect Looking for something a little earlier? Check out the cross-staff, a
What about collectibility? Today, firms like Weems & Plath wooden rod that forced sailors to look at the sun, or the back staff,
still manufacture sextants, but the majority of them are purchased by which fortunately allowed the user to take measurements with the sun
private sailors as backups. Older sextants are part of a niche group behind him. The astrolabe is equally rare, but you can find these and
of antique maritime and navigational technology that found its audience other outmoded navigational instruments at auction or via specialty
in England amongst sailing enthusiasts and interior decorators, dealers, such as Tesseract of Hastings on Hudson or George Glazer
and headed west. Gallery in New York City. Fleaglass.com also compiles several venues
Now, more than ever, sextants find places of prominence amongst that carry antique science and technology. Be prepared to pay in the low
technology or maritime collections, in gentleman’s libraries, or as an thousands at least for these instruments from dealers, but particularly
homage to exploration paired with a classic ship portrait. Antique with sextants, the cost can be worth it for this functioning piece of
sextants can bring anywhere from hundreds to several thousand maritime history. Owning one might just save your life someday.
dollars if in top condition. As essential
navigation tools, sextants were typically
treasured by sailors who might have
received or proudly purchased one as they
progressed up the ranks.
Collectors will benefit from the fact
that they were often well-cared for and
frequently come with their boxes, a
testament to the antique sextant’s place of
honor on any ship. Sextants also got passed
down when sailors retired, taking on
multiple generations of significance. They
were such prominent symbols that you’ll
even find sextants and octants carved
into tombstones, particularly those of
New England sea captains, to chart their
way to heaven.

The backstaff predated the sextant and was used by
standing with the sun at your back and noting the
shadows cast by the upper vane on the horizon
vane to determine your angle. It was invented
by navigator John Davis and is often
called a Davis Quadrant.
Photo: National Museum of the US Navy
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