This is an antique vintage travel or pocket Barometer by the acclaimed manufacturer, M Pillischer of London. The dial has a pressure range of 20-31 inches and an altitude range of 0-12,000 feet. The outer altitude ring rotates by turning the upper milled brass casework. The beveled glass crystal and brass casing are in very good condition. The silvered dial is tarnished but the markings are perfectly legible – please check the photos carefully. I do not know if this instrument is correctly calibrated or if it is functioning correctly and it is being sold “as is” — BUT the pointer does move  as the atmospheric pressure changes –  You will see that some pictures were taken on different days and show the pointer in different positions.
The barometer comes in its original velvet-lined hinged case keep the top and bottom halves closed. The case is very worn with some losses but it has served its purpose of protecting the instrument for well over 100 years .
Approx dimensions are 1 7/8” diameter x 5/8” depth