sions, either the science or the practice is wrong. A practice' 

 not based upon science may be right, or it may be wrong, just 

 as a man may guess right or wrong, but at best such practice, 

 whether in agriculture or engineering, contains too many ele- 

 ments of uncertainty. Few would care to contend that the Brook- 

 lyn bridge could have been built without first, theoretically, de- 

 termining the strain on each part ; before a blow was struck 

 the strain on every piece in that great structure was computed, 

 and also the dimension of the parts required to safely withstand 

 this load. 



Good judgment, unaided by the science of the civil engineer, 

 could hardly have directed the efforts of two gangs of men from 

 paints five miles apart, and given us the Hoosac tunnel. The 

 fact that small enterprises are carried through successfully with- 

 out the aid of science is too often used as a argument that theory 

 is useless ; because some small stream has been successfully 

 bridged by some one who never knew how to compute the strain 

 on a given brace, or post, or rod, therefore there is no need of ap- 

 plying the principles of mechanics to bridge building. This 

 kind of reasoning is all wrong, and, to-day, no engineering pro- 

 ject is undertaken without first working out the most minute de- 

 tails from a theoretical standpoint. Every brace and bolt, post 

 and pin, every block of granite, first appears "on paper" in the 

 office of the draughtsman, before a blow is struck by the work- 

 men, who are to construct the bridge. 



Theory and practice must go hand in hand to arrive at the 

 best results in the best way. This is as true in agriculture as in 

 anv other pursuit. 



The two factors with which we have to deal in stock feed- 

 ing are plants and animals, and we will briefly consider the prin- 

 ciples of their growth and composition. 



Plants and animals are mutually dependent iox their existence. 



Without //a«/j', animals would perish, and without animals^ 

 plants would in time die for lack of an atmosphere suited to 

 their wants. 



PLANT GROWTH. 



When a kernel of corn is planted under favorable circum- 

 stances it produces a stalk and ear that may weigh five pounds. 

 It is evident that the little kernel, w>.nghing but a small fraction 

 of an ounce, could not have furnished all the material from which 



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