Tricarbon or C₃ is a small carbon cluster first spectroscopically observed in the beginning 20th century in the tail of a comet by William Huggins and subsequently identified in stellar atmospheres. Tricarbon can be found in interstellar space and can be produced in the laboratory by a process called laser ablation. Small carbon clusters like tricarbon and dicarbon are regarded as soot precursors and are implicated in the formation of certain industrial diamonds and in the formation of fullerenes. The ground state molecular geometry of tricarbon has been identified as linear via its characteristic symmetric and antisymmetric stretching and bending vibrational modes and bears bond lengths of 129 to 130 picometer corresponding to those of alkenes. The ionization potential is determined experimentally at 11 to 13.5 electron volt. In contrast to the linear tricarbon molecule the C₃⁺cation is bent.

C₃ has also been identified as a transient species in various combustion reactions.^{[citation needed]}

Ion Lewis (1853 – August 29, 1933) was a founding member of Whidden & Lewis, a prominent architectural firm in Portland, Oregon, United States around the beginning of the 20th century. The firm was formed with partner William M. Whidden. Their residential buildings were mostly in the Colonial Revival style, while their commercial buildings were primarily in the twentieth-century classical style. The commercial buildings often featured brick, along with terra cotta ornamentation. Many of their buildings are listed on the National Register of Historic Places (NRHP). Lewis was born in 1853 in Boston, Massachusetts, and moved to Portland in 1881. Some buildings he designed include Portland City Hall, the Multnomah County Courthouse, and the Forestry Building from the Lewis & Clark Exposition. Lewis died on August 29, 1933.