Pocket barometer/altimeter by negretti and zambra of london. The barometer responds to increases in pressure within a sealed bag. The outer altimeter ring rotates as expected. Shows some scratches and a blemish on the dial (near 27) but there is no effect on the performance. The serial number on the dial is 467.The item “Pocket Barometer-Altimeter by Negretti & Zambra, London” is in sale since Sunday, March 30, 2014. This item is in the category “Antiques\Science & Medicine (Pre-1930)\Scientific Instruments\Barometers”. The seller is “rowel” and is located in Williamsburg, Virginia. This item can only be shipped Worldwide.