I agree for two reasons: both Knotel and Rousselot have illustrations of enlisted voltigeurs wearing colpacks, and the Knotel watercolors were in the collection of John Elting who also did research work on the subject. In point of fact, Col Elting was an excellent uniformologist in his own right. And both Knotel, who improved on the work of his father, and Rousselot did extensive research on uniforms.