The technics of bel canto

One of the primers in the Old Italian School of Singing, The technics of bel canto (1905) by Giovanni Battista Lampert can be read or downloaded here.

A slender thirty-one page document, it was written five years before Lamperti's death at the age of seventy-one. He dedicated it to his student Marcella Sembrich, the great Polish coloratura soprano who taught at the Curtis Institute of Music in Philadelphia and the Juilliard School of Music in New York.

Page seven of the text represents something of a mystery. It contains a 'Diagram of Action of the Diaphram' that shows the body from an lateral angle and the movements of the abdominal wall which are labeled a) inspiration and b) expiration. The former is 'in' while the latter is 'out'. What is curious is that, in my hard copy (and all others I have seen),  this label is pasted onto the page, suggesting that the printed designation of inhalation and exhalation was reversed in the original printing. This begs the question: did Lamperti make a mistake which was corrected by the publisher? Or did an editor make the change?

What do you think?