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LARGE STATION POINTER /3-ARM PROTRACTOR BY CARY, c.1850
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LARGE STATION POINTER /3-ARM PROTRACTOR BY CARY, c.1850
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A large, fine brass station pointer or 3-arm protractor made by the well known instrument maker - Cary, London, circa 1850. There is a trade label of Henry Porter and a correction table on the lid ( please see photo for details). The instrument had been repaired and adjusted by Henry Porter, who signed the date and noted the index errors in 1886? Henry Porter was apprenticed to William Cary and later took over his business. The station pointer consists of a graduated circle and threearms, one of which is fixed (at 0 degrees on the scale), while the other two can move around the circle and have fixing screws. The circle has a diameter of 7 3/4 inches (197mm) and is made of brass with a silvered degree scale. The scale runs from 0 to 360 degrees (going both ways) with verniers on the movable arms. It is contained in a fitted wooden case, which also holds extension pieces for each of the arms, fixing screws. A station pointer is used for plotting a ship’s position from horizontal sextant angles taken between two or more objects or geographical features. To use it, the angles measured by the sextant are used to set the positions of the movable arms around the circle on the station pointer. This can then be placed on a chart to draw position lines from the features observed and so plot the ship’s position. Station pointers are also used in surveying, in which case they have verniers attached to the movable arms to allow more accurate positioning, as this example does. "Cary London" is engraved on the instrument, and "R27" is engraved on the fixed arm. The instrument is about 22 inches long and 34 inches with extension pieces on. It is in excellent condition, all you need is a little polish on the silvered scale, but I'd prefer it untouched.The instrument is fitted in its beautiful original dove tailed mahogany case with brass hinges, turn-locks and green felt trims inside. It is also in excellent condition, but the name plate's missing from the top of the case. The case measures approx. 23 1/4 x 8 3/4 x 2 inches (590 x 220 x 50 mm) Please see photos for details. I've set a very low starting price for this great instrument, so good luck to you all on bidding. If you're bidding from overseas, please ask for a quote for shipping before bidding. Check out my other items ! Be sure to add me to your favourites place
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