42 FARM MACHINERY 



used, as they have a supply of oil which is carried up to 

 the top of the shaft by a chain or ring. It is necessary 

 to replenish the supply of oil only at rather long inter- 

 vals. 



64. Electrical transmission.* Power may be trans- 

 mitted by converting mechanical energy into electrical 

 energy by the dynamo, and after transmission to a dis- 

 tance be converted into mechanical energy again by the 

 electric motor. This form of transmission has many ad- 

 vantages where the electric current is obtained from a 

 large central station, and no doubt will be an important 

 form of transmission to the farmer of the future, as 

 electric systems are spread over the country for various 

 purposes. 



*See Chapter XXII., Part II. 



