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 6145-01-442-1852
NSN 5975-00-837-3293
NSN 6220-01-105-7929
NSN 6620-00-349-8013
NSN 6150-01-230-5909
NSN 6220-01-367-6411
NSN 5925-01-325-1989
NSN 4140-01-565-3744
NSN 7035-00-150-2379
NSN 5985-00-144-8170
NSN 5915-00-241-3676
NSN 6685-00-925-7491