Historical origin of the four-piece triangle-to-square dissection

Determine whether the four-piece dissection transforming an equilateral triangle into a square was originally invented by Henry E. Dudeney or by C. W. McElroy, resolving the ambiguity in historical attribution.

Background

The paper recounts the early 20th-century history of the triangle-to-square dissection puzzle, noting that Dudeney published the four-piece solution in 1902 while crediting Mr. C. W. McElroy for finding a four-piece solution earlier. The authors highlight that the precise origin of the construction remains uncertain.

Resolving the authorship would clarify historical records around one of the most famous dissections and inform the attribution of this influential geometric construction.