514 THE POPULAR SCIENCE MONTHLY. 



T am throwing my experiences at Niagara into a readable shape, intending to 

 make a Friday evening lecture out of them on the 4th of April. As soon as 

 ever the paper is ready I shall send it to you. 



I have not yet got properly into harness ; indeed, this is always a difficulty 

 with me. When I get into a rut I tend to persist in it. 



Had a letter yesterday from Hector. He tells me that he has forwarded the 

 deed of trust to Prof. Henry. I did not keep a copy of it, and should like some 

 time to have one, but there is no hurry. . . . Yours ever, 



John Tyndall. 



April 12, 1873. 



Ml Deak Youmans: The "Tyndall number," as the World calls it, of The 

 Popular Science Monthly duly reached me. I wish you had sent over a dozen of 

 them. I took the number to Bence Jones (who to my great grief is dying) and 

 to others. They were mightily struck by its tone, and Bence Jones predicts all 

 manner of great things for a nation which can evoke the spirit manifested in the 

 address of President White. 



... I send you by this post a proof of my little paper on Niagara ; it may be 

 printed as it stands if time be an element of importance,* otherwise I am having 

 a little map of the Falls prepared which will add to the clearness of the paper. . . . 



Faithfully yours, John Tyndall. 



THE PSYCHOLOGY OF A DOG. 



By JOHN MONTEITH, 



IN his recent work on Justice, Mr. Herbert Spencer turns a new- 

 light upon old questions in ethics, by tracing the roots of 

 ethical principles to the animal community. There is something 

 wonderful in the way certain animals form a society and ex- 

 emplify the egoistic and altruistic sentiments of justice working 

 in harmony. With all their selfish quarrels and contests, the 

 compact of animals throws many an attempt at human combina- 

 tion into the shade. 



But such co-operation by limitation and adaptation is only 

 possible where there is power of perception, thinking, emotion, 

 and purpose. Therefore, we must either assume or constantly 

 prove, until demonstration is secured, that some animals, like 

 human beings, think, reason, and feel, and execute intelligent 

 purposes. Do they ? 



It is in the line of answer to this question that I introduce the 

 subject of the following sketch, and record some careful observa- 

 tions I have made of the mental operations of my subhuman 

 dog. I am unable to gratify the curiosity of the fancier touching 



* This very interesting paper may be found in the third volume of The Popular Science 

 Monthly, page 210. 



