Construction, Maintenance, and Repairing of Aircraft Instruments JA Gordon Beaufort as documented in the aircraft's

as documented in the aircraft's parts list dated 1951

While we don't know the year of manufacture

The indicator displays aircraft mach speed from 0

It has some slight water damage on one page

Construction, Maintenance, and Repairing of Aircraft Instruments JA Gordon Beaufort as documented in the aircraft'sThis 30 page document is a reprint by Henry Paulson & Co. of content of Construction, Maintenance, and Repairing of Aircraft Instruments by J. A. Gordon from London's Horological Journal. The Henry Paulson firm appears to have been engaged in the manufacturing and or marketing of precision instrument tools and equipment. It appears that they also published technical references and catalogs such as this in an effort to expand their service offerings to