A "PORTABLE AIR METER"

A "PORTABLE AIR METER", maker Bottomley, London, the signed dial with five subsidiary dials, numbered 1802, with pivotting sand filled "egg" timer and horizontal "fan", raised on baluster columns and cylindrical base, dial 2 1/4" diameter, in original fitted case, the hinged cover with owner's name plaque "R A Quain, Engineer, Leadenhall House, E.C.", the interior with correction label and instruction leaflet (Est. plus 21% premium inc. VAT)