Explanation of Grammatical structure is needed
The crowd saw him clap his hand to his mouth.
This is a sentence from Harry Potter I. I don't understand how "clap" is used right after "saw". Shouldn't there be a "to" in between? i.e. "saw him to clap" seems appropriate.
There are two verb constructions of the type verb + object + infinitive.
The normal construction is verb + object + to-infinitive as in
- I want you to help me.
A small group of verbs use only bare infinitive:
1 All verbs of perception as eg to see, hear, feel etc.
- I heard the girls laugh ("laughing" is also possible).
2 Verbs of cause and allowance:
to make s (someone) do sth, to have s do sth, older: to bid s do sth - to let s do sth
You make me laugh. Let the children come to me.
I searched the Internet for information about these two verb constructions. What I found is miserable.
A verb of perception can take an object + bare infinitive.
I saw two men cut down a tree.
A bare infinitive means a complete action here.