This treasure is a Lufft Barometer Altimeter with leather case in excellent operational condition.  The scale is in millimeters so 76 is = to 760 mm or 29.92 in inches.  The top beveled crystal is scratch free and in excellent condition as is the instrument.  These barometer altimeters were prevalent in 1800s to early 1900s for balloonists, mountain climbers and early fliers.  They are very rare and seldom found in perfect operational condition.  Serial number is stamped 18543 with script name of Lufft in center.  Testing with instrument inside a plastic baggie and squeezing shows needle movement.  History preserves that in the early 1870s Lufft began making began making precision scientific instruments in Stuttgart, Germany.  Like most successful entrepreneurs, i.e. Bill Gates, Lufft made these in a garage like environment.  Note – there is no date on this item, but Lufft made this model in the middle 1870s.  In 1881, he set up a factory to manufacture scientific instruments.  The instrument has an adjustment screw to adjust current altitude.  The case is gold tone with light pitting.  Size is 2” in diameter x 1” high.  Collectors of scientific instruments will know the Lufft name and rarity that will highlight any collection of 1800s Barometers Altimeters in original case.