maugorn's right, and you are mistaken that Wikipedia says otherwise. Wikipedia: "Later, from around the 15th century, the word came to mean the use of three breves in a bar when the prevailing metrical scheme had two dotted breves in each bar."
When I'm being really persnicketty, I differentiate between implicit and explicit hemiolas, the latter being where there is a second line (or more lines!) of music keeping the predominant rhythm in explicit counterpoint with the one in the hemiola, the former being as per "Como Poden".
Five bucks says that the original source notates those measures explicitly as hemiolas, i.e. in red ink where the measure is in three.
Whoops. Read in haste right past the bit about shift in meaning.
I couldn't find the tune in the web-accessible scans of the 'T' manuscript. In the scans of the 'E' manuscript all the notes are black ... but the illuminated letters look kinda funny, so I'm guessing that these are black and white scans of more colourful pages. I'd be very interested in seeing better images.
Re: Nomenclature
When I'm being really persnicketty, I differentiate between implicit and explicit hemiolas, the latter being where there is a second line (or more lines!) of music keeping the predominant rhythm in explicit counterpoint with the one in the hemiola, the former being as per "Como Poden".
Five bucks says that the original source notates those measures explicitly as hemiolas, i.e. in red ink where the measure is in three.
Re: Nomenclature
I couldn't find the tune in the web-accessible scans of the 'T' manuscript.
In the scans of the 'E' manuscript all the notes are black ... but the illuminated letters look kinda funny, so I'm guessing that these are black and white scans of more colourful pages. I'd be very interested in seeing better images.