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.
