Unusual Barometer by F. Darton & Co. London

This is quite a rare barometer by well known makers, F Darton & Co. The dial refers to their London base which they vacated in the early 1920s and move their entire offices and manufacturing facility to larger premises in Watford, Herts. I would therefore guess this instrument can be dated to around 1910. I describe it as quite rare as not only does the dial show atmospheric pressure from 24 inches to 31 inches, the outer scale is an altimeter ranging from zero to 7000 feet. Whilst this arrangement is not uncommon in pocket barometers of the era, I've not seen a similar one as this size. The set hand is not the usual brass knob secured in the centre of the glass which moves the hand behind the glass but is a small pointer behind the bevelled glass and is positioned by rotating the milled brass bezel. Attached to the brass hanging ring is an old style screwdriver fixed to a handwritten note in black ink stating 'key for setting weather ('glass'?)'. There is a solid oak surround with brass feet enabling the instrument to be desktop or shelf mounted. I suspect this addition is as old as the actual instrument and may well have been commissioned by the original buyer. Shipping to UK addresses via Royal Mail Next Day, Tracked & Insured service £20. Overseas by UPS -check with me for cost. Alternatively, you are welcome to collect from me by arrangement in Somerset.