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 6105-00-464-9316
NSN 2925-00-082-8219
NSN 5905-01-467-1529
NSN 5910-00-649-4498
NSN 6610-00-221-6124
NSN 5905-01-594-2232
NSN 5925-01-335-1908
NSN 5945-01-241-7750
NSN 6220-01-583-3278
NSN 5855-00-973-5717
NSN 5950-00-888-9673
NSN 6620-01-207-8043