easy calculations and adjustments 63
A sextant has eight standard parts.
Frame: The weblike structure that
holds all other parts. The frame
approximates 1/6th of a circle, thus
the name sextant.
Arc: The curved piece of metal or
plastic running along the bottom of
the frame. Lines engraved on the
arc show whole degrees.
Index Arm: The arm attached to the
top of the frame. Squeezing two clamps
at the bottom of the arm enables it to
move up and down the arc.
Micrometer Drum: The wheel near
the index-arm clamps, with marks
showing minutes. This is used to
fine-tune an observation.Index Mirror: A small mirror attached
to the top of the index arm that captures
the reflected image of an observed
object.
Horizon Glass: Attached to the front
of the frame, one half is clear and one
half is a mirror.
Shade Filters: Both the index
mirror and horizon glass have shade
glasses to protect the eye from water
surface glare or direct sunlight.
Telescope: The scope power
should not exceed 5X. More powerful
scopes have too small a field of
view, making the observed image
difficult to view.The Parts of a SextantMicrometer DrumFrameHorizon Glass TelescopeShade Filters Index MirrorIndex ArmArc