THE CASSENS & PLATH SEXTANT
This sextant is the most popular
of the traditional solid brass professional sextants in the world today.
Made in the finest tradition of German craftsmanship, it has a guaranteed
accuracy of better than 10 seconds of arc. The frame and arc are constructed
of a special brass alloy, and the entire instrument has been treated and
enameled to prevent corrosion. The handle is inclined to provide a more
natural grip. The mirrors are of the finest optical quality. For daytime
observations, both fixed, and variable density polarized sunshades are
provided for both the index and horizon mirrors. Lighting of the micrometer
drum and arc is powered by 2 size AA penlight batteries contained in the
handle.
A distinctive feature of all Cassens
& Plath models is a drum index corrector. This is a separate smaller
knob that extends forward from the micrometer drum. Turning it allows the
index error to be quickly corrected to zero by resetting the micrometer
drum indication. All models are supplied in a nicely finished wooden
instrument case.
Two Models to Choose From
The Cassens & Plath is available
in two models: the Standard, and the Horizon Ultra models. These two models
are essentially identical, except that the Horizon Ultra incorporates a
double prism lens which indicates perpendicularity of the sextant to the
horizon. Each model is available with either a whole horizon or traditional
split horizon mirror.
SPECIFICATIONS
| Arc |
-5° + 125°, radius 162mm |
| Accuracy |
± 10", throughout the arc |
| Micrometer Drum |
1' scale, vernier to 0.2' |
| Mirrors |
56 x 42 mm index, 57 mm horizon |
| Horizon Shades |
1 Fixed and 1 Polarized |
| Index Shades |
2 Fixed and 1 Polarized |
| Weight |
4 lbs. (brass) |
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THE HORIZON ULTRA MODEL The Horizon Ultra is available in either a white or
traditional black finish. Apart from personal preference in looks, the white
finish is considered to be more resistant to tropical heat insofar as expansion
and contraction are concerned. However, our feeling is that this problem is
minimal due to the engineering design of the frame which is not unduly affected
by thermal changes. The double prism lens is a beveled clear lens which is mounted
as a sun shade and shows a discontinuity in the horizon if the sextant is not
perpendicular to it. This lens can be readily introduced into the field of view,
or stowed out of the way at the viewer's option. This very nice feature, however,
can only be used with a whole horizon mirror. The traditional split mirror blocks
half of the field of view and obscures the discontinuity, rendering it ineffective
For this reason, the Horizon Ultra is normally recommended only with a whole
horizon mirror, altough a traditional split mirror may be installed if desired.
THE STANDARD MODEL The Standard model is offered in a black finish,
and is offered with a traditional split mirror. It does not have
the double prism lens.
Choosing a Model In light of the foregoing; if one wants a traditional
split mirror, the standard model is a good choice since the double prism lens feature of the
Horizon Ultra could not be used anyway. Conversely, if one wants a whole horizon mirror, the
small additional cost to have the double prism lens with the Horizon Ultra is recommended. If
undecided, or if contemplating changing mirrors at a later date, choosing the Horizon Ultra
leaves the most options open.
Included and Optional Equipment
The sextant comes with a 3.5x40
telescope and wooden case as standard equipment. Optional items include a 7x35 telescope, zero
magnification sight tube, a practice bubble horizon which facilitates
effective back-yard practice without the need for a sea horizon, and a more expensive
Professional Artificial Bubble Horizon. This provides a 2X power artificial horizon for use
on land, or at sea if extremely calm conditions exist and the natural horizon is not visible.
It connects to batteries in the handle for night lighting, and incorporates a dimming rheostat
for use with faint stars. Shipping weight includes all accessories which are ordered from this page. SW 16 lbs.
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