PART SECOND.
THE ELEMENTS op
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Although several authors have written excellent trea- tises on the Art of Perspective, it is to be feared that they have presupposed such an acquaintance with ge- ometry, as is seldom attained by youth for whom this work is designed. A complete treatise is not intended, but merely such a familiar illustration of the first princi- ples of perspective as a common mind, acquainted with the former part of this work, may be able to compre- hend. All that has been attempted is the laying of a good foundation for future progress, should these few pages excite in the pupil a desire to know more of this useful and elegant art.
There is probably no one who has not remarked, that objects at a distance appear much smaller than their real size. The cause of this is to be found in the structure of* the eye, and in the laws of vision. To il- lustrate these laws, draw a right line of any length with a pen, then place the rule parallel to the line ; mark with the thumbs the length of the line upon the rule, and holding the thumbs there, stretch the arms at full length. Then begin gradually to draw the rule towards
