POWER MACHINERY ON THE FARM 353 



Another important point is to keep all bearings and bolts 

 just tight enough. Any looseness in the joints of a machine 

 greatly increases the strain and wear on it. And a machine 

 should be used reasonably and sensibly, that is, do not 

 unduly strain it, unless absolutely necessary, either by run- 

 ning it too fast or by overloading it. 



Cost. — The use of most machines must be justified on 

 the basis of cost. That is, can the work be done as cheaply 

 or more cheaply with the machine than without it? There 

 are several different items to consider in determining the 

 cost of a machine for doing work. Some of the more im- 

 portant items are depreciation, interest on investment, 

 shelter, repairs, insurance, oil and fuel. Depreciation means 

 the wear or lowering in value. If a machine is worth $100 

 at the beginning of the year and only $80 at the close of the 

 year, we say that it has depreciated $20. Cost is a pretty 

 reasonable basis for determining the practicability of a 

 machine and should always be considered. Sometimes, 

 however, in fact, quite often, cost alone is not a sufficient 

 argument for not using a machine. A home may be lighted 

 with kerosene lamps, more cheaply than by electricity, 

 nevertheless electricity in the home is a good investment, 

 if it can be afforded. 



A man may be able to plow more cheaply with horses 

 than with a tractor, but the tractor may enable him to do 

 his work more quickly and j ust at the right time, so that 

 it might pay him to use a tractor even at a higher cost. 



Again, machines may interest boys and girls and keep 

 them at home satisfied when they would otherwise leave. 



Suggestions. — Such a general and elementary text as 

 this can not give detailed information concerning the opera- 

 tion of farm machinery. The best we can do is to advise 

 our readers to study carefully the directions sent out with 

 each machine. Occasionally some operator can improve 

 upon these directions, but generally many costly mistakes 

 are made by not following them. The manufacturer of 

 farm machinery is very anxious that the users of his machine 

 shall get good service and be satisfied. He has generally 

 tried his machine under a great many different conditions 

 and knows how it will do the best work. Hence, the wise 



