THE LAW OF LIKENESS, AND ITS WORKING. 233 



tory has his " personal equation " duly ascertained, and has 

 this correction applied to each of his observations. This most 

 interesting fact relates exact or mathematical science in the 

 most curious manner to the mental character of an individual. 

 Mr. Galton, however, does not rest merely with the announce- 

 ment of this latter result. He goes much further in his 

 theoretical inquiry, and suggests that peculiarities in the 

 respect just noted might be found to be related to special 

 points in the conformation of the body. Thus could the 

 " personal equations " of astronomers be related to the 

 height of body, age, colour of hair and eyes, weight and 

 temperament, some valuable facts might be deduced regard- 

 ing the union of definite characters to form a special con- 

 stitution. 



Some other methods may be cited of estimating the 

 differences between various temperaments in appreciating 

 sensations and in acting upon them. If a person is prepared 

 to give an instantaneous opinion as to the colour of a certain 

 signal black or white but is unaware of the particular 

 colour which is to be exhibited, and if he is further instructed 

 to press a stop with his right hand for the one colour and a 

 left-hand stop for the other, the act of judgment necessary 

 to determine the particular stop in each instance is found to 

 occupy an appreciable interval. This is particularly the case 

 if a single signal has been previously shown, and the ob- 

 server's quickness of sight has been tested and calculated by 

 his pressing a single stop whenever he saw the object. The 

 comparison between the interval elapsing between the mere 

 sensation of sight and the act of pressing the stop in the 

 latter case, and the interval which elapses when the observer 

 has to make up his mind as to the difference between two 

 signals, is seen to be very marked. 



Setting thus before his mind a certain number of tests of 

 individual temperament and character such as have been 

 illustrated, the observer may next proceed to the task of 

 discovering whether persons who exhibit similar qualities of 

 mind in these experiments can be proved to be related to 



