A precisely calibrated instrument used as a master reference standard to establish an absolute horizontal plane. The metal base is seasoned and heat treated or otherwise specially treated to insure maximum stability, and is accurately machined and scraped to the true plane on the contact surface. The top plate is of nonconductive heat insulating material. It has a very sensitive vial graduated to indicate a variation of 0.0005 inch (0.0127 mm) per foot (0.3048 m) in a horizontal plane. It may have a cross level vial to assist in setting the true horizontal by showing position laterally.
Classification: Other measuring or checking instruments, appliances and machines, nesoi in chapter 90
NSN 5835-01-408-2503
NSN 6650-01-100-2637
NSN 6320-00-593-0379
NSN 5990-01-395-4194
NSN 5835-01-128-9331
NSN 7035-00-521-6423
NSN 2925-01-511-5359
NSN 6240-01-633-9357
NSN 5999-01-398-9541
NSN 5915-00-589-4186
NSN 6135-00-505-0679
NSN 6135-00-919-1117