With a vacant air he regarded the Pandemonium, and a petrifaction of his inner being seemed to take place.
No spark of animation visited his eye
Pandemonium - metaphor for the city as a noisy and busy place
Petrifaction of his inner being - his mind is overcome so he becomes like an unresponsive stone in his mind.
No spark of animation visited his eye - he stares at the city with no expression.
[His coworkers tease him and say he is like an elephant. Then another one says of this person:] Oi,oi, his nose would betray him.
There is an implication the "he" is very large, and that he has very big nose.
He became aware with growing dread of something abrewing out of the common
There is something about to happen[ abrewing] that is not usual [out of the common] and he is afraid of what it might be.
'T is often that kind weeps sorest when it's too late.
Describes a person who is always slow in seeing a consequence and is therefore late in responding to it.