I left out the following sentences. Thank you very much.

1) His dictionary definition of a horse underlines how Mr. Gradgrind has choked his Bitzer's imagination.
2) The black of the soot (can soot be replaced by ash and smoke?).
3) Dickens compares the up-and-down movement of the piston of the steam engine (and not steam engine's piston) to the (shaking??) head of an elephant in a state of melancholy madness.
4) In contrast with Sissy (incorrect, better: Unlike Sissy), Bitzer is light haired and light eyed.
5) He calls his students by their number in the class register.

1 answer

1. "...has choked his Bitzer's imagination." Should "his" be in there?

2. yes

3. "the steam engine's piston" is smoother

4 and 5 - OK