Can you please check if everything is OK in these sentences? Thank you.
1) He can’t sleep for hours but then he falls asleep after drinking the drugged water. When he wakes up he can see the size of his prison and realizes that the pit is about half the size he calculated.
2)He also sees that his prison is square and that the wall is covered with iron, with horrible figures, such as skeletons.
3) The floor, on the other hand, is made of stones. The ceiling is thirty to forty feet overhead and is similar to the wall. Hanging from one of the iron plates he sees a huge pendulum that seems to be moving.
4) Then he hears a noise and sees lots of enormous rats coming up from the pit, attracted by the smell of the food. He cannot move because he is now bound to a wooden board by a long strap.
5) Looking up at the pendulum, he realizes that its movement has become wider and quicker and that it is getting closer to his body.
6) Its lower part is of bright steel, about a foot long; the horns are upwards and the bottom is as sharp as that of a razor. It hangs from a brass rod and it hisses as it swings through the air.
1. two commas needed
2. OK
3. comma needed
4. OK
5. comma needed
6. comma needed
Everything else is OK.