I did not realize how many antique billiard books were digitized and freely available on the net. Just for curiosity I checked out Side and Screw: Being Notes on the Theory and Practice of the Game of Billiards (1901) published in 1901, by Charles Dealtry Locock
I could only handle a little, but he seems to talk about all the same kind of pool physics that "the science guys" argue about today...
And Michael Phelan, writing in Billiards Without a Master in 1850:
"To the physiognomist and the silent observer of human
nature, there is no 'game that more thoroughly discloses
the various dispositions of men than Billiards. The ela,-
ted hope, the depressing fear, the sanguine exultation, the
mortifying defeat — ^the philosophical resignation to fate,
the indifference of success, and all the multiplied and
manifold passions of the human mind, are variously de-
picted and easily discovered, by an attentive observer, on
the countenance of the Billiard player. In fine, a Billiard
Room is a school where the study of human nature can
be pursued to advantage. ."