ROSS. — DESIGN AS A SCIENCE. 361 



while unequal attractions balance in the same way, but at distances which 

 are inversely proportional to them, as attractions. Measures, shapes, and 

 colors being equal, values alone differing, values 4 and 1 balance on value 

 0, at distances 1 and 4 respectively. If the ground-tone were 2 instead 

 of 0, 4 and 1^ would balance on 2, at distances 1 and 2 respectively. In 

 this explanation of the balance of values we find the principle upon which 

 the designer proceeds when he wishes to create such a balance. He may 

 prefer to depend upon his visual feeling, but his feeling must be guided 

 by the law of balance whether he thinks of the law or not. 



The scale of values is not merely a scale of visual attractions to be bal- 

 anced, it is also a rhythmic movement of values. The scale-relationship 

 is not, properly speaking, a relationship of opposition or antithesis ; it is 

 one of association or joint action. The values of the scale combine to lead 

 the eye in a movement from light to dark, or from dark to light, and 

 this movement is easy in proportion to the perfection of the scale. If 

 the scale is imperfect, if the intervals are not equal intervals of equal 

 contrasts, we have the same discomfort that we have in walking on the 

 irregularly placed sleepers of a railway track. We all know how tire- 

 some it is to do that. Not only is the eye led in the scale of values 

 from dark to light and from light to dark, but if the values be squeezed 

 together the eye is led quickly or abruptly ; if they are pulled apart the 

 movement is comparatively slow or gradual. By changing the direction 

 or the shape of the scale of values the eye may be led in different direc- 

 tions, and its movement may take a variety of shapes. A few simple dia- 

 grams would show the rhythmic character of the scale of values in these 

 several aspects. Values are in harmony when they are in the same scale, 

 and when the relations of the scale can be felt, visually. The least 

 contrast of the scale is a factor of the greatest, and when this relation is 

 distinctly felt we have a perception of harmony. The most perfect har- 

 mony is that of corresponding values. 



Tone, as we have seen, means two things: value and color. We have 

 been considering the element of value. We will now consider the other 

 element, color. In order to do that satisfactorily we must eliminate all 

 differences of value. Producing as many differences of color as we can, 

 all in the same value (the half-tone between white and black), and all in 

 the same measure and shape (the circle of half an inch radius), we shall 

 find that we can produce perhaps twelve differences of color, and in each 

 color a certain number, perhaps eight differences of intensity. In order 

 to study color without being confused with the differences of intensity, let 

 us put all the colors not only in the same value, but in the same degree 



