They are singular because mathematic and mathematics are the same thing, as well as physics; It's not like there are physic and physics.
you have to look for figurative language in the poem
It was a Victorian room. The authencity of each and every detail made it obvious. Richly carved book cases. Lining the shelves were books covered with intricate detail, the gold lettering spidery and delicate. The ornamentation along the desk; The parquet floor: everything a Victorian Library had made it seem vintage and cosy.