of a gallon of oil per H. P. per hour is required to work 

 an oil-engine. The plnnt for generation of gas from coal 

 is also expensive and oil engines are therefore more econo- 

 mical than gas engines. Oil and gas engines require less 

 skill in management and they may be set in motion at less 

 time, but they are, on the other hand, more liable to get out 

 of order, having more little parts where soot may lodge, &c. 

 Where sudden but temporary suspension of work causes 

 great inconvenience, e. g. in electric lighting, steam engines are 

 found more satisfactory than oil or gas engines, but in farm 

 operations such occasional stoppage causes no particular incon- 

 venience. The boiler and the firebox of a steam engine are 

 expensive to renew from time to time as they have to be. 

 Less water also is needed for working gas and oil engines, as 

 the water is required only for cooling the cylinders. Gas and 

 oil engines are particularly suitable for intermittent work. 

 In working steam engines time is taken up in getting up 

 steam and if this has to be done two or three times a day 

 there is waste of resources. Steam engines are however very 

 useful where the use of steam for heating, cooking, clearing 

 and sterilising is of primary consideration as in a dairy-farm 

 or a fruit-farm where jam and jelly are made on the premises. 

 Except for such special purposes, a portable oil engine is 

 to be preferred to a steam engine for farm use, where the 

 owner has the means of introducing such forms of power. 



162. Electricity. This power is cheaper per unit than 

 either horse, steam or any of the other forms of power we 

 have been speaking of. The use of electricity in agriculture 

 is, on the whole, still in an experimental stage. Electric 

 lights are used for stimulating the germination and growth 

 of plants. The use of electricity on a large scale for driving 

 thrashing machines, chaff-cutters, kibblers &c., and even 

 for ploughing, has been inaugurated by an association of 

 farmers in Bavaria. The current which has a pressure of 

 5,000 volts, is generated partly by water-power and partly by 



