| Trackable Options |
Found this item? Log in. |
Printable information sheet to attach to Faber Optimé - Gettin Sexy!
Print Info Sheet |
|
One of the primary navigational aids 300 years ago, the sextant is so called
because its scale has a length of one sixth of a full circle (60°), from the
Latin sextāns.
Simply, a sextant is a device that measures the angle between two
objects.
The sextant makes use of two mirrors. With the sextant shown in the following
diagram, one of the mirrors (mirror A) is half-silvered, which allows some light
to pass through. In navigating, you look at the horizon through this mirror.
The other mirror (mirror B) is attached to a movable arm. Light from an
object, let's say the sun (hence the need for the multiple dark filters seen on
more elaborate models), reflects off this mirror.
The arm can be moved to a position where the sun's reflection off the mirror
also reflects off mirror A and through the eyepiece. What you see when this
happens is one object (the sun) superimposed on the other (the horizon). The
angle between the two objects is then read off the scale.
What makes a sextant so useful in navigation are its ability to provide exact
location by triangulations with the sun/known stars and its accuracy.
It can measure an angle with precision to the nearest ten seconds (a degree
is divided into 60 minutes; a minute into 60 seconds).
Using the Sextant
In order to work as intended, a sextant requires both a subject (e.g. an
island, a boat, a visible destination) and an object. Typically, the object is
above the horizon. At night, objects such as stars and the moon can be used
directly. During the day however (because this sextant has no filters), one must
use a landmark visible above the horizon (other than the sun).
Do not look at the sun with this sextant!
Rotate the eyepiece so that it is aligned directly at the half mirror.
Looking through the eyepiece, move the sextant so that the object is clearly
visible in the middle, above the half mirror.
Level the sextant so that the top of the half mirror is aligned with the
horizon.
Holding the sextant steady, move its lever, until the subject is seen in the
bottom of the half mirror (vertically below the object).
The number shown on the scale is the angle between the subject and the object.
Problems?
Travel Bugs need maintenance from time to time (as do we all?!). If this one looks in need (or if you would like to know how to make your own
capsule), please take a look at the Faber Optimé Travel Bug Maintenance Manual.
A PDF file of the custom stash note for this travel bug can be obtained here.
About Faber Optimé
|
 We aim to deliver excellence, in all of our
activities - such as bringing to you curious, interesting and
innovative geocaches and geocache items, like this one.
Keep your eyes peeled for more of the Faber Optimé
Travel Bugs!
We're always happy to help fellow geocachers!  Please do feel free to get in touch with us on
the following contact details.
|
 |