







A rare and luxuous English rectangular protractor made in silver, engraved J. The protractor, small in size, measures 10.8cmx3.3cm. As well as the usual angular scale the instrument two line of 1-180 degrees and on the other side a diagonal scale for plotting distances on a map or plan ; on the other side, 6 reduction or chart scales. English silver instruments from this period are rare. For another example of a nearly similar size but later produced by Nairne, see Catalogue of the Andrew Alpern Collection number 11, pages 22-23. The penultimate photo shows the image of a Sisson trade card illustrating this same type of protractor, and the last photo shows the size difference between a standard-sized rectangular protractor and this example by Sisson.
