The constellation created by Nicolas-Louis de Lacaille to represent a chisel is Caelum.
Caelum is a small, faint constellation in the southern sky. Its name is Latin for “chisel,” and older forms included Caelum Sculptoris, meaning “the engraver’s chisel.” Lacaille introduced it during his mid-18th-century survey of the southern heavens, where he added constellations inspired largely by instruments associated with science and the arts.
Lacaille observed from the Cape of Good Hope and catalogued nearly 10,000 southern stars. His southern-sky work led to 14 new constellations, including Caelum, Microscopium, Pictor, and Telescopium. In Lacaille’s original depiction, Caelum represented a pair of engraving tools rather than simply one modern carpenter’s chisel.
Caelum is easy to confuse with nearby Pictor, which represents an easel, or Sculptor, which represents a sculptor’s studio. It is also among the faintest official constellations: Alpha Caeli, its brightest star, is only about magnitude 4.45.