Soru

The following passage is adapted from an essay on the history of dendrochronology:

Dendrochronology, the scientific method of dating tree rings to analyze past atmospheric and environmental conditions, was pioneered in the early twentieth century by Andrew Ellicott Douglass, an astronomer at the University of Arizona. Seeking to understand how solar activity influences terrestrial weather patterns, Douglass initially examined cross-sections of yellow pine trees from northern Arizona in 1904. He noticed that trees growing in the same regional climate exhibited matching patterns of wide and narrow rings corresponding to wet and dry years.

By 1914, Douglass had established a continuous tree-ring chronology extending back several centuries. However, extending this chronology further into the past required finding older timber specimens preserved in human structures. In 1929, while analyzing artifacts excavated from ancestral Puebloan ruins at Pueblo Bonito in New Mexico, Douglass examined a crucial wooden beam cataloged as HH-39. By matching the outer ring patterns of HH-39 with the inner rings of previously dated specimens, Douglass bridged a persistent gap in his master chronology, establishing that the main construction phase of Pueblo Bonito occurred between 1082 CE and 1128 CE.

Based on the passage, in which year did Douglass analyze the wooden beam cataloged as HH-39?