Page:A Voyage in Space (1913).djvu/132

112 to. If the object is not magnified enough you can take out this little eyepiece and put in another which magnifies more. Perhaps you have had your photograph taken and "enlarged": something of the same kind happens with a telescope, the big lens or mirror makes a little image and the eyepiece enlarges it.

Now you may have noticed that when your photograph is enlarged, various defects appear which were not noticeable in the original small photograph: and the more you enlarge it the more these defects are emphasized, so that to enlarge it beyond a certain point is no advantage. Fig. 29 is a picture of a horse and jockey from the Daily Graphic: and an enlargement of the head of the jockey. The enlargement (Fig. 30) shows that the head is all composed of little dots, and though these