X. EXPOSITION

+152.  Purpose of Exposition.+—­It is the purpose of exposition to make clear to others that which we ourselves understand.  Its primary object is to give information.  Herein lies one of the chief differences between the two forms of discourse just studied and the one that we are about to study.  The primary object of most description and narration is to please, while that of exposition is to inform.  Exposition answers such questions as how? why? what does it mean? what is it used for? and by these answers attempts to satisfy demands for knowledge.

In the following selections notice that the first tells us how to burnish a photograph; the second, how to split a sheet of paper:—­

1.  When the prints are almost dry they can be burnished.  The burnishing iron should be heated and kept hot during the burnishing, about the same heat as a flatiron in ironing clothes.  Care must be taken to keep the polished surface of the burnisher bright and clean.  When the iron is hot enough the prints should be rubbed with a glace polish, which is sold for this purpose, and is applied with a small wad of flannel.  Then the prints should be passed through the burnisher two or three times, the burnisher being so adjusted that the pressure on the prints is rather light; the degree of pressure will be quickly learned by experience, more pressure being required if the prints have been allowed to become dry before being polished.  White castile soap will do very well as a lubricator for the prints before burnishing, and is applied in the same manner as above.

—­The Amateur Photographer’s Handbook.

2.  Paper can be split into two or even three parts, however thin the sheet.  It may be convenient to know how to do this sometimes; as, for instance, when one wishes to paste in a scrapbook an article printed on both sides of the paper.

Get a piece of plate glass and place it on a sheet of paper.  Then let the paper be thoroughly soaked.  With care and a little skill the sheet can be split by the top surface being removed.

The best plan, however, is to paste a piece of cloth or strong paper to each side of the sheet to be split.  When dry, quickly, and without hesitation, pull the two pieces asunder, when one part of the sheet will be found to have adhered to one, and part to the other.  Soften the paste in water, and the two pieces can easily be removed from the cloth.

EXERCISES

A. Explain orally any two of the following:—­
    1.  How to fly a kite.
    2.  How a robin builds her nest.
    3.  How oats are harvested.
    4.  How tacks are made.
    5.  How to make a popgun.
    6.  How fishes breathe.
    7.  How to swim.
    8.  How to hemstitch a handkerchief.
    9.  How to play golf.
   10.  How salt is obtained.