Your GPS screen has nothing on this. In fact, by comparison, the fancy GPS with all its technowizardry is quite bland and boring. This, my friends, is a sextant. Before GPS and LORAN the sextant was the primary means of determining your position on the planet.
The concept the sextant relies on actually dates back to Sir Isaac Newton himself. He never published or really developed his concept for a doubly reflective navigation instrument, so it wasn’t until 1730 that the octant, which uses a scale of 1/8 of a turn or 45 degrees, was developed by John Hadley and Thomas Godfrey in England and the US, respectively. The sextant, which has a scale of 1/6 turn or 60 degrees, is merely an improvement on the octant with greater accuracy for measuring the distances between celestial bodies for longitude measurements.
Using a sextant is not that hard, but it takes some skill and some artistry to master it. Basically, you sight the horizon in the telescope through the horizon mirror and move the arm and a fine adjusting screw to adjust the the index mirror until a celestial body (the sun, Polaris, etc.) is lined up with the horizon. You look a few things up in a book and — Voilà! — you know where you are. Maybe.
The real artistry of a sextant is that the measurements made must be very precise. If you’re just 4 seconds off on the time, your position will be wrong by a nautical mile. Knowing this, it’s incredible the old time sailors found anything!
Today, most sextants are display pieces. Although, since it does not require electricity it is considered to be the most reliable backup to GPS. So, if you’re in the market for a boat you should consider a sextant, as well. I want one just so I can continue to use the word “sextant”. It makes me giggle.
[Image Credit: brasscompass.com]
I came here to demand an explanation of how to use a sextant, but, Mr. Neerd, you beat me to it. Thanks!
Using the sextant is an art. I had great respect for navigators who used them on aircraft because of the difficulties of compensating for speed, cloud and turbulence. But no matter how good they were you still would have an area of uncertainty. The infamous "cocked hat", a triangle that could be a hundred miles to a side.
Cool. I've never used a sextant, but I do have quite a bit of experience with surveyor's transits.
<img src="http://www.antiqbuyer.com/images/ARCHIVE_PICS/Survey_Archive/KE-Archive/transit_ke_solar2.jpg">
Reliable mechanical clocks were also an essential development that led to accurate navigation across long distances.
<img src="http://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/MIH-film12_color_cerrected_denoise.jpg/220px-MIH-film12_color_cerrected_denoise.jpg" width="400">
http://en.wikipedia.org/wiki/Chronometer
Although Chronometer does not have the giggle inducing power of sextant…
How about "poop deck"?
Shiver me timbers! Makes me want to stick my yard arm in your port hole!
http://www.talklikeapirateday.com/translate/
Got to love the early technology!No chips,no batteries.
I still have my slide rule,although it is a bit dusty.
Back in high school, I was in a humanities class whose final project was to teach an old skill to the class. I chose to teach how to use a sextant, which actually is surprisingly easy. The hard part is knowing what to do with the information it provides you!
I wanted to learn how to use a sextant after I mastered the slide rule, which is kicking my ass.
Now it has become painfully apparent, that being focused too on math can adversely affect your sextant life.
Very cool,I wanted to buy a sextant .