Compass made by W. M. Welch Mfg. Co. of Chicago, Illinois.  The company changed its name to Welch Scientific in 1960.  Compass was made to military specifications as it is official green with military nomenclature.  Measures 4 1/2" in diameter, 5 5/8" in length.  Welch is not listed in Charles Smart's book  "The Makers Of Surveying Instruments In America Since 1700"