dix 5, rule 10.

In the first sentence it is evident that the intent of the writer is to
separate, in thought, _the boy that broke his leg_ from all other boys.
Although the clause does indeed describe the boy's condition, it does so
_for the purpose_ of _limiting_ or _restricting_ thought to one especial
boy among many. In the second sentence the especial person meant is
indicated by the word _eldest_. The clause, _who is now in England_, is
put in for the sake of giving an additional bit of information.

+38. Constructions of Relative Pronouns.+--Relative pronouns may be used
as subject, object, object of a preposition, subject of an infinitive, and
possessive modifier.

The relative pronoun is regarded as agreeing in person with its
antecedent. Its verb, therefore, takes the person of the antecedent: [_I_,
who _am_ your friend, will assist you].

The case of the relative is determined by its construction in the clause
in which it is found: [He _whom_ the president appointed was fitted for
the position].

+39. Compound Relative Pronouns.+--The compound relative pronouns are
formed by adding _ever_ and _soever_ to the relative pronouns _who,
which_, and _what_. These have the constructions of the simple relatives,
and the same rules hold about person and case: [Give it to _whoever_
wishes it. Give it to _whomever_ you see].

+40. Interrogative Pronouns.+--The pronouns _who, which_, and _what_ are
used to ask questions, and when so used, are called _interrogative_
pronouns. _Who_ refers to persons; _what_, to things; and _which_, to
persons or things. Like the relatives _who_ has three case forms; _which_
and _what_ are uninflected.

The implied question in the sentence, I know whom you saw, is, Whom did
you see? The introductory _whom_ is an interrogative pronoun, and the
clause itself is called an _indirect question_.

The words _which, what_, and _whose_ may also be used as modifiers of
substantives, and when so used they are called _interrogative adjectives_:
["_What_ manner of man is this?" _Whose_ child is this? _Which_ book
did you choose?].

+41. Demonstrative Pronouns.+--_This_ and _that_, with their plurals
_these_ and _those_, are called _demonstrative pronouns_, because they
point out individual persons or things.

+42. Indefinite Pronouns.+--Some pronouns, as _each, either, some, any,
many, such_, etc., are indefinite in character. Many indefinites may be
used either as pronouns or adj