Why is it "in the university" rather than "at the university" in these examples?

The title of an 1848 book is The Organization of Industry, Explained in a Course of Lectures Delivered in the University of Cambridge in Easter Term 1844.

The cover page of this 1864 book states that William Edward Hearn is "Professor of History and Political Economy in the University of Melbourne".

But according to the answer here, it should be at the university. Was this just some archaic 19th century thing and we now always use "at the university" rather than "in the university" in these contexts? Or was there something special about the above contexts?

Solution 1:

"lectures delivered in the University of Cambridge": Here we are talking about the location. Where were the lectures delivered? Answer: In the University of Cambridge. Here we know that the venue for these lectures was the University of Cambridge.

"lectures delivered at the University of Cambridge": Here the focus is on the institution. These lectures might or might not have been delivered in the university campus. But they were facilitated by the institution (University of Cambridge) as maybe a part of their curriculum or special lecture series or some other similar program.