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Sir Howard Douglas navigational quadrant for sale on eBay

A rare navigational instrument signed 'Cary, London', patent 73, dating from around 1825.As a result of clever design, this instrument can be used to take instantaneous sightings of objects separated by up to 120 degrees, so facilitating a rapid determination of a given position.
The 110mm. Linear plotting scale under the semi-circular scale (reading to one minute of the arc) is divided in units of ten from 0 to 1760, the interpolation grid being divided every single unit.
This instrument was invented by Sir Howard Douglas of the Royal Military College at Farnham and is essentially a combination of both Hadley's quadrant and a protractor.
Thus angles can be plotted directly without recourse to the reading of angular scales.
The instrument measures 145 mm. X 192 mm.
The radius of the semi-circle is 54 mm.
The box measures 110 x 168 x 46 mm.
The instrument retains the majority of the original finish and is in very good order.

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Comment by Russell Lynn Drysdale on June 8, 2011 at 2:38
I wish i had the Cash , I would take that off the market .

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