WINDMILLS AND PUMPS. 383 



width. It will be the square feet of area of each float 

 submerged at one time that will be the measure of the 

 power in a uniform current. 



The current, or bucket, wheel is quite an institution 

 in many large streams, and it is a good thing where 

 the current is steady and strong. By attaching buck- 

 ets to its arms or vSweeps, sufficient water can be raised 

 to irrigate small tracts close to the stream. The turn- 

 ing of the wheel by the current at the same time fills 

 the buckets, which are emptied at a certain hight into 

 a trough or flume, and in this way the water is carried 

 to the land. 



Gasoline Engines. — Very effedlive pump power 

 can be gained by the use of the portable gasoline 

 engine, which consists of base, cylinder, piston, con- 

 nedling-rod, crank-shaft, and fly-wheels. The modus 

 operandi and the development of power is as follows : 

 In starting up, on the first outstroke of the piston a 

 mixture of air impregnated with the proper amount of 

 gasoline is drawn into the cylinder, passing through 

 the valve chambers. On the instroke of the piston, 

 this mixture in the cylinder is compressed into space 

 between the cylinder-head and the piston. The com- 

 bustible mixture is then ignited by the most reliable, 

 safe, and simple device possible — a short iron tube 

 closed at the outer end and conne(5led to the interior 

 of the cylinder, enclosed in a chimney and heated by 

 a burner ; and the air being expanded by the heat in- 

 volved, an impulse is given to the piston. When the 

 piston has reached the second outstroke the exhaust- 

 valve is opened and remains open during the second 

 instroke of the piston, and the produ<5ls of combustion 



