Casgliadau Arlein

steel and brass circular protractor stamped Norton & Gregory of London & Glasgow. There are no other identification marks or Patent Numbers. The instrument (presumably for drafting or plotting) is in the form of a steel circle 145mm max. dia. (15mm wide) which is marked off at ½º intervals with numbered divisions each 10º up to 360º. The inner edge of the circle is notched at each 90º. There are 4 radial 'arms' at 90º to the centre. The centre is in the form of a smaller circle 35mm in ext. diameter with an opening of 15mm in the middle: onto this is set a hollow-centred brass disk. An 'arm', pivoted from the centre, can be rotated around the circle - it is 160mm long measured from the centre and can be used for accurate measurements down to 1 minute of an angle through the Vernier scale. Towards the end of this arm is a scribing or locating pin. The instrument comes in a hinged mahogany box 248mm x 172mm x 36mm (when closed). Inside, in one corner is a small compartment 29mm x 24mm in which is housed a tiny bakelite folding magnifying glass