Historian David Schnakenberg dates the piece to 1876 - the date shown at the top of the triangular arch of the center building of the Deere factory complex in the illustration.
The name "Moline" is shown on the toolbox, and 1847 (the year Deere's Moline Plow Works was established) appears in two places (at the top of the center building's triangular arch, and between the first and second floors on the left-most building) replacing the 1876 notation on the earlier pieces.
One may think then that this result was affected by alterations in parafunctional habits, often concomitant with class II, which tend to result in triangular arches
. In his study in class I and class II Caucasian population, Nojima, (30) reported a prevalence of lower arch triangular shape of 46.7% and 69.8% respectively.