IMAGES AND SHADOWS. 



669 



in tlie shutter. There will then be formed upon the white surface an 

 inverted picture of the external objects, as shown in Fig. 3. They 

 will appear of the natural colors, and the outlines will be sharper in 

 proportion as the hole is smaller. 



When the sun shines through a small orifice into a darkened room, 

 a cone of rays is produced, as everybody has observed, by lighting up 

 the particles of dust which are scattered in its course ; for, if the air 

 were quite clear, the track of the rays would be invisible. In this 

 case an image of the sun is formed upon the floor or opposite wall by 



Fig. 5. 



€gH . <flfc 



Images of Sun formed bt Foliage. 



the crossing of the rays through the aperture, exactly in the manner 

 of the production of the candle-image and the landscape-picture just 

 described. The best condition for the formation of suqh an image is 

 when the sun is low, and there is a white wall opposite to receive it ; 

 the image is then perfectly circular. But if the light falls upon the 

 floor, as represented in Fig. 4, the cone of rays produces an oblong or 

 elliptical image ; the deviation from an exact circle depends upon the 

 angle which the cone of rays makes with the floor. Such an image 



