This is from Punchinello, a nineteenth-century American spinoff of Punch.
If the text is too small for you to read, here’s what it says:
Lecturer. “There is a cumulative approximativeness, so to speak, a period when the recalcitrant corpuscles begin to” –
Stenographer. “Con-found the fellow ! I knew he’d break my pencil with his infernal jaw-smashers!”
If you like the artwork, you’ll find some more here