I'm fairly sure it's ἐγχειρήσεως, the genitive of ἐγχείρησις which here probably means something like "manipulation, operation".
It's written ἐν- instead of ἐγ- but my guess is that the Latin transliteration has interfered with the spelling here, and also if it were εὐ- the breathing mark would be written over the υ and not the ε. That it's a genitive goes with "hujus". I know only the very basics when it comes to the ligatures in Greek, but I do recall that the large circle represent a σ and it does seem to be circling an ω-like shape. But no matter how sure I might be, this is still a guess.
Edit: it seems like I remembered wrong -- if you look at this Wikipedia article
it has a picture of the -ος ligature that matches the one here, so the circle is the ο and the squiggle inside is the σ. I still think it's the same word but it's just the Latin transliteration encheireseos transliterated back into Greek by someone who didn't know Greek very well.