+252.+ We have three adjectives which are used so commonly that we have
put them in a class by themselves. These three little words are _a_,
_an_ and _the_, and we call them articles. The word _article_ literally
means a little joint or limb, and these three little words are so
closely connected with the nouns with which they are used that they seem
to be a part or joint or limb of the noun itself, and so we have called
them articles.
_A_ and _an_ are called the _indefinite_ articles because they point out
an object in a very indefinite manner. _The_ is called the _definite_
article for it points out in a more definite way.
We use _a_ before words beginning with a consonant sound, as _a man_, _a
tree_, _a book_; and we use _an_ before words beginning with a vowel
sound, as _an apple_, _an editor_, _an orange_, _an heir_. In _heir_ the
_h_ is silent, and we say _an_ because the word begins with a vowel
sound. _A_ is used before words beginning with _u_ because long _u_ is
equivalent in sound to a consonant, for the blending of the sounds of
which long _u_ is composed produces the initial sound of _y_, which is a
consonant sound. For example, we say, _a university_, _a useful work_,
etc., and not _an university_. Before words beginning with short _u_,
use _an_, as, _an upstart_, etc.
In deciding whether to use _a_ or _an_, watch the initial _sound_ of the
word, not the initial _letter_. If it is a vowel sound use _an_, if a
consonant sound, use _a_.