A device used in making surfaces level or at right angles to a plumb line. The “leveling instrument” (Heb., mish·qeʹleth or mish·qoʹleth) was employed by carpenters, stonemasons, and other craftsmen of  ancient times to achieve horizontal accuracy when building walls and various structures, while the plummet was used to assure vertical accuracy. Egyptian masons seem to have employed a level shaped like the letter “A” with a short plumb line suspended from the apex. Evidently when the hanging line coincided with a center mark on the crossbar, this indicated that the surface on which it was placed was level. The Scriptures furnish no description of leveling instruments, however, and they refer to this device only in figurative ways.

A leveling instrument may be used to construct a building properly or to test its fitness for preservation. Jehovah foretold that he would apply to wayward Jerusalem “the measuring line applied to Samaria and also the leveling instrument applied to the house of Ahab.” God had measured and found Samaria and the house of King Ahab to be morally bad or crooked, resulting in their destruction. Likewise, God would judge Jerusalem and its rulers, exposing their wickedness and bringing about the destruction of that city. These events actually occurred in 607 B.C.E. (2Ki 21:10-13; 10:11) Through Isaiah the various wicked braggarts and rulers of the people in Jerusalem were apprised of their coming calamity and of Jehovah’s declaration: “I will make justice the measuring line and righteousness the leveling instrument.” The standards of true justice and genuine righteousness would reveal who were really God’s servants and who were not, resulting in either preservation or destruction.​—Isa 28:14-19.