31G THE POPULAR SCIENCE MONTHLY. 



" This process is without precedent. The use of sand in sawing marble, or 

 in grinding glass by common methods, hardly furnishes an analogy." 



Here follows a description of the device, concluding with the state- 

 ment that "it is regarded by the judges as being one of the most re- 

 markable and valuable inventions which the age has produced." 



When it is announced that the judges who thus emphatically in- 

 dorsed the claims of the sand-blast were Profs. Barnard, Mayer, and 

 Morton, our readers will demand of the writer no apology for or quali- 

 tication of his expressed opinion that the " Tilghman sand-blast is an 

 invention which, in simplicity of construction and extent of application, 

 has hardly an equal in the annals of American patents." 



-- 



mSTmCT AND ACQUISITION.^ 



Br D. A. SPALDING. 



SO great was the influence of that school of psychology which main- 

 tained that we and all other animals had to acquire in the course 

 of our individual lives all the knowledge and skill necessary for our 

 preservation, that njany of the A^ery greatest authorities in science 

 refused to believe in those instinctive performances of young animals 

 about which the less learned multitude have never had any doubt. 

 For example, Helmholtz, than whom there is not, perhaps, any higher 

 scientific authority, says: "The young chicken very soon pecks at 

 grains of corn, but it pecked while it was still in the shell, and when it 

 hears the hen peck, it pecks again, at first seemingly at random. Then, 

 when it has by chance hit upon a grain, it may, no doubt, learn to 

 notice the field of vision which is at the moment presented to it." 



At the meeting of this Association in 1872, I gave a pretty full ac- 

 count of the behavior of the chicken after its escape from the shell. 

 The facts observed were conclusive against the individual-experience 

 psychology. And they have, as far as I am aware, been received by 

 scientific men without question. I would now add that not only does 

 the chick not require to learn to peck at, to seize, and to swallow 

 small specks of food, but that it is not a fact, as asserted, and generally 

 supposed, that it pecks while still in the shell. The actual mode of 

 self-delivery is just the reverse of pecking. Instead of striking forward 

 and downward (a movement impossible on the part of a bird packed 

 in a shell with its head under its wing), it breaks its way out by vigor- 

 ously jerking its head upward, while it turns round within the shell, 

 which is cut in two chipped right round in a perfect circle some dis- 

 tance from the great end. 



' Read at the Bristol meetinor of the British Association, 



