An Introduction to a Biology 



as that which would make it very difficult for anyone to 

 explain that the angle which the two arms of a " governor " 

 on an engine make to one another, becomes obtuse in pro- 

 portion as the speed of rotation becomes great, if he lived 

 in a world in which " governors " always travelled at a 

 constant rate such as would keep the two arms at a con- 

 stant angle of 90 degrees to each other. Table VI. might 

 convey nothing to the mind of anyone regarding it even 

 after he had read the first part of this paper. But a cine- 

 matograph, the successive pictures composing the film of 

 which were the successive dot-Tables on the Plate, would 

 show movement resulting from known causes. Cause, " no 

 dice left down " has effect " circular blur." Cause, ' " 12 

 dice left down " has effect " diagonal line." Cause, " 6 dice 

 left down " has effect intermediate between the last two 

 effects. 



Imagine that you have a small model of a " governor." 

 If you do not touch it the arms hang down. If you spin 

 the axis as fast as you can, the arms lie in the same straight 

 line. Spin it at a moderate rate ; the arms make an angle 

 of 90 degrees to each other. 



Directly we can play with machinery we can see how it 

 works. Movement and change enable us to perceive and 

 to understand. 



The two squares intersected by diagonal lines in Table I. 

 are squares in which from the conditions of the experiment 

 a throw cannot fall. In the rest of the Tables, the same 

 is true of all the intersected squares and of all the squares 

 to that side of the intersected ones remote from the diagonal 

 of the Table. 



