| NOMENCLATURE |
LEVEL, PRECISION, MASTER. A PRECISELY-CALIBRATED INSTRUMENT USED AS A
MASTER-REFERENCE STANDARD TO ESTABLISHAN 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 TO
INDICATE THE HORIZONTAL PLANE. IT MAY HAVE A CROSS-LEVEL VIAL TO SHOW
POSITION LATERALLY.
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