A youth to fortune and to fame unknown.—­GRAY.

[Sidenote:  Changes material to class nouns.]

191. An or a before a material noun indicates the change to a class noun, meaning one kind or a detached portion; as,—­

They that dwell up in the steeple,... 
Feel a glory in so rolling
On the human heart a stone. 
—­POE.

             When God at first made man,
     Having a glass of blessings standing by. 
     —­HERBERT.

The roofs were turned into arches of massy stone, joined by a
cement that grew harder by time.—­JOHNSON.

[Sidenote:  Like the numeral adjective one.]

192.  In some cases an or a has the full force of the numeral adjective one.  It is shown in the following:—­

     To every room there was an open and a secret
     passage.—­JOHNSON.

     In a short time these become a small tree, an inverted pyramid
     resting on the apex of the other.—­THOREAU.

     All men are at last of a size.—­EMERSON.

     At the approach of spring the red squirrels got under my house,
     two at a time.—­THOREAU.

[Sidenote:  Equivalent to the word each or every.]

193.  Often, also, the indefinite article has the force of each or every, particularly to express measure or frequency.

     It would be so much more pleasant to live at his ease than to
     work eight or ten hours a day.—­BULWER

[Sidenote:  Compare to Sec. 184.]

     Strong beer, such as we now buy for eighteenpence a gallon, was
     then a penny a gallon.—­FROUDE

[Sidenote:  With such, many, what.]

194. An or a is added to the adjectives such, many, and what, and may be considered a part of these in modifying substantives.

     How was I to pay such a debt?—­THACKERAY.

     Many a one you and I have had here below.—­THACKERAY.

     What a world of merriment then melody foretells!—­POE.

[Sidenote:  With not and many.]

195 LIST III.

  A few of comparative form but not comparative meaning:—­

       After Over Under Nether.

Not and never with a or an are numeral adjectives, instead of adverbs, which they are in general.

     Not a drum was heard, not a funeral note.—­WOLFE

     My Lord Duke was as hot as a flame at this salute, but said
     never a word.—­THACKERAY.

NOTE.—­All these have the function of adjectives; but in the last analysis of the expressions, such, many, not, etc., might be considered as adverbs modifying the article.