My friend Alec is a professional seaman who, while in France, came across an old sextant in a small antique shop near the waterfront. He was intrigued, but returned to his ship where he e-mailed me, asking what I thought.

I answered, "If it calls to you, buy it."

He made an excuse of finding some non-fat milk to get ashore, raced to the antique shop, bartered with the elderly owner, and walked out with the sextant.

"When I held that sextant in my hand, I felt many different things," he wrote. "I could feel the ghost of one sailor's cold hands, one generation of sea captains handing down to another generation, perhaps a junior officer learning noon sights from his captain. Maybe it was responsible for ships safely crossing oceans, maybe it was lowered down on a rope to a lifeboat that was leaving a sinking ship. You don't know the significance until you are at sea and your life depends on it. It is something worth its weight in gold the minute you cross the 90-fathom curve leaving Spain and Africa. Maybe it's my destiny to hand this sextant down the line..."

If ever there were a perfect description of why we collect nautical memorabilia, this was it: Because it makes us feel good when we look at it or hold it. His sextant, perhaps two centuries old, was brass and ebony and faded mirrors, with the scale inscribed on yellowed ivory. It was from a time when ships creaked and canvas sails pulled hard, and just holding it had converted Alec into a collector looking for more.

Let's look at some other nautical collectibles:

Sextants
Sextants and their kin (octants, backstaffs, and quadrants) are in demand as collectibles for many reasons. The craftsmanship is usually superb, particularly since lives depended upon their accuracy, and the materials of mahogany, ebony, ivory, and brass make for an interesting display.

Most collectors of nauticalia are involved with the sea, often as yacht owners, so sextants are both familiar and alien. We live in a world of chart plotters and satellite navigation, but sextants are a reminder that noon sights and star shots were once the very essence of navigation and something that every skipper knew well. Even today, many ocean races require a celestial navigator and a sextant aboard, just in case the electronics go zap.

Octants were in use from the time John Hadley designed the first in 1731, and sextants were developed from the octant, entering common use around 1800. Most were made with brass frames, and silver often replaced ivory for the scales. For security, all came in sturdy boxes, usually with a certificate inside the lid noting the last accuracy check. One basic visual difference between the two devices is the sextant has a scale occupying one-sixth of a circle, while the octant is smaller at one-eighth of a circle.

Because sextants were found on every ship and captains often carried their own, they are not uncommon and can be found at many dealers that specialize in antique or scientific instruments. Be wary, however, because fake sextants are flooding the market. At press time, a 19th century sextant with silver scale, two sights, and a fitted mahogany case was offered by a reputable British dealer for about $750. For shopping tips, visit Antique & Scientific Instruments UK at www.asiuk.net/nautical.htm.