Altimeter, Air Section US Signal Corps, 15,000FT, WWI
This is an Altimeter used in military aircraft of the Aviation Section, US Signal Corps, which existed from 1914-1918 and was the WWI-era precursor to today's US Air Force. Made by Taylor Instruments, item # 2081-A.
This altimeter crudely measured altitude from 0-15,000 ft. By loosening the small retaining lever, gripping the knurled rim of the faceplate and turning, the numerical scale rotates clockwise or counter-clockwise while the pointer remains stationary, to correct the altitude reading as required. This looks very similar to the altimeter depicted in the JN-4D Curtiss Jenny cockpit at the US Naval Aviation Museum website.
It is in very good condition given its age. The rim is very stiff to rotate and needs attention to loosen it. Measures 6 inches diameter and ~2.5 inches deep.