IPA: /ˌmænəˈmɛtrɪkli/
KK: /mænəˈmɛtrɪkli/
In a way that relates to the measurement of pressure using a device called a manometer.
The pressure was measured manometrically to ensure accuracy in the experiment.
Manometrically → It is formed from "manometer" (from Greek "manos" meaning thin and "metron" meaning measure) and the suffix "-ically" (meaning in a manner relating to). The word "manometrically" refers to something done in a manner relating to the measurement of pressure using a manometer.
Think of measuring something 'thin' ('manos') and 'in a manner' ('-ically') related to pressure — that's what manometrically means.