FARMEES' INSTITUTES. 149 



tured article, and wo liave Avonderful machines for locomotion either on land or 

 water. 



The very fact that there is so much money in our machinery has led many an 

 unprincipled man into its manufacture. The country is literally flooded with 

 worthless patent rights, and every collection of agricultural implements contains 

 many got up utterly devoid of any mechanical iirinciple. The smooth-tongued 

 vendor of these worthless implements describes in glowing terms their wonderful 

 qualities, and frequently Avill sell his implement where the less talkative dealer 

 in more reliable implements will fail. 



Much loss has been occasioned by overlooking the simple principles which 

 govern the working of machines and implements, and a few have suffered them- 

 selves to be imposed on and deceived, when a simple and ready application of these 

 principles would at once have detected errors, without resorting to an expensive 

 trial. The day should be past for the commission of such blunders, as the man who 

 thought he was favoring the weaker horse in his team by giving him the shorter 

 end of the whiffletree ; or of the other man who balanced the bushel of grain on 

 his horse's back by putting the grain in one end and a large stone in the other; 

 or of still another man, who, in order to rest his horse's back when riding to 

 mill on the bag of grain, transferred the grain, Avithout alighting, from the 

 horse's back to his own shoulder. That the day is not past when less obvious 

 blunders of the same sort are sometimes committed, is positively proved by the 

 fact that many agents of worthless imtent riglits are every day growing richer. 

 The principal reason for the community in general being so easily dui^ed by the 

 patent-right vendor, is on account of their ignorance of just the amount of work 

 a machine should do. There are two great laws which, if thoroughly mastered, 

 will protect the farmer in his purchases, and assist the manufacturer in his con- 

 struction. The first is the "law of virtual velocity," or, in other words, 

 ** whatever is gained in time is lost in power," and vice versa. This, stated in 

 another way, is, Forces are always equal when the products of tlie power, multi- 

 plied by the distance, are equal." You are all familiar with examples of the 

 application of this law. If you take a straight stick, say three feet long, and 

 put its center over a block for a fulcrum, it will remain at rest, or balance ; 

 that is, the forces acting on each end are equal. The same results will be true 

 if you put a pound weight on each end ; but if you move one of the weights six 

 inches nearer the fulcrum the bahince is destroyed. In the first case, supposing 

 the weights to be each two pounds, and the distance 18 inches ; you had, by the 

 rule stated, power X distance = power times distance, or 2 X 18 = 2 X 18 ; 

 while in the second case you had 2 pounds at 12 inches = 2 pounds at 18 inches, 

 or 2 X 12 = 2 X 18j which is absurd. But you can make one pound balance 

 two pounds by placing one pound twice as far from the fulcrum. This is true, 

 bothin practice and theory, for 1 X 18 inches = 2 X ^ inches. You know that 

 shortening the distance or lever arm has the same effect as the lightening of 

 the Aveight, and you have here also learned that when one weight was lightened 

 equilibrium was restored by a corresponding lengthening of its lever arm. 



Now placing the stick with its center over the fulcrum and moving the end 

 up and down, each end will move with the same velocity, for it will pass over 

 an equal space in the same time. Moving the stick so that the fulcrum is twice 

 as near one end as the other, the same motion gives one end (the one on tlie 

 long side) twice the velocity of the shorter one, for it passes over twice the space 

 in the same time ; and by this we see that the velocity and the lengtli vary the 

 same, and consequently in any given exj)ression we can substitute the one for 

 the other. 



